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Bio-functionalization of grade V titanium alloy with human type I human collagen for enhancing and promoting human periodontal fibroblast cell adhesion – an in-vitro study
Abstract
Surface modification of medical grade V titanium alloy (Ti-6Al-4V) with biomolecules is an important and vital step for tailoring it for various biomedical applications. Present study investigates theinfluence of type I human collagen (T1HC) bio-conjugation through a three stage process. Polished grade V titanium alloy discs were functionalizedwith free OH group by means of controlled heat and alkali treatment followed by coating of 3-aminopropyltriethoxy (APTES) silane couplingagent. T1HC were bio-conjugated through 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride N-hydroxysuccinimide (EDCNHS)coupling reaction. At each stage, grade V titanium alloy surfaces were characterized by atomic force microscopy (AFM), scanning electronmicroscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Xrayphotoelectron spectroscopy (XPS). FTIR and XPS studies confirms thecovalent attachment of APTES with titanium alloy surface while terminalamine groups of APTES remained free for further attachment of T1HCthrough covalent bond. Aqueous stability of bio-conjugated titanium discsat various pH and time intervals (i.e. at pH of 5.5, 6.8 and 8.0 at timeinterval of 27 and 48h) confirmed the stability of T1HC bioconjugated collagen on titanium surface. Further human periodontalfibroblast cell line (HPdlF) culture revealed enhanced adhesion on theT1HC bio-conjugated surface compared to the polystyrene and polishedgrade V titanium alloy surfaces.
... 83 Medical-grade titanium alloys with unmodified surfaces contain an oxide layer that protects it from corrosion under normal physiological conditions but is associated with a net negative charge that is nonconducive for cell adhesion and proliferation in vivo. 84,85 Hence numerous strategies have been employed to alter the surface of Ti implants to promote cell attachment and growth for improving its biointegration with host tissue in vivo. Toward that end, surface modification of Ti alloy discs was performed via a two-step process in which hydroxyl groups were first introduced on the alloy surface via heat and alkali treatment, following which silanization with (3aminopropyl)triethoxysilane yielded a surface containing free terminal amine groups that can be utilized for biofunctionalization procedures. ...
... 84 This technique has been employed to bioconjugate type I human collagen (T1HC) on to Ti surfaces via carbodiimide coupling reaction to improve cell adhesion characteristics of modified Ti surface. 85 Results demonstrated that T1HC coated substrates amplified adhesion and growth of human periodontal fibroblast cells compared to uncoated Ti alloy surfaces. 85 Along similar lines, HA−titanium dioxide (HA-TiOx) nanohybrid composite was coated on titanium substrates by electrophoretic deposition to confer hydrophilic surface characteristics for enhancement of cell adhesion and proliferation. ...
... 85 Results demonstrated that T1HC coated substrates amplified adhesion and growth of human periodontal fibroblast cells compared to uncoated Ti alloy surfaces. 85 Along similar lines, HA−titanium dioxide (HA-TiOx) nanohybrid composite was coated on titanium substrates by electrophoretic deposition to confer hydrophilic surface characteristics for enhancement of cell adhesion and proliferation. 86 Similarly, plasma sprayed nano/micro ceramic oxide coatings based on alumina and zirconia have also been attempted to evaluate its biocompatibility and antibacterial activity on Ti alloy surfaces in vitro. ...
Biomedical research in health innovation and product development encompasses convergent technologies that primarily integrate biomaterials science and engineering at its core. Particularly, research in this area is instrumental for the implementation of biomedical devices (BMDs) that offer innovative solutions to help maintain and improve quality of life of patients worldwide. Despite achieving extraordinary success, implantable BMDs are still confronted with complex engineering and biological challenges that need to addressed for augmenting device performance and prolonging lifetime in vivo. Biofabrication of tissue constructs, designing novel biomaterials and employing rational biomaterial design approaches, surface engineering of implants, point of care diagnostics and micro/nano based biosensors, smart drug delivery systems, and non-invasive imaging methodologies are among strategies exploited for improving clinical performance of implantable BMDs. In India, advances in biomedical technologies have dramatically advanced health care over the last few decades and the country is well positioned to identify opportunities and translate emerging solutions. In this article, we attempt to capture the recent advances in biomedical research and development progressing across the country and highlight the significant research work accomplished in the areas of biomaterials science and engineering.
... Collagen is the main component of the extracellular matrix in mammals, and is mainly distributed in the cornea, cartilage, bone, blood vessels, viscera, intervertebral discs, and dentin, and plays an important role in supporting and protecting the body and organs. Collagen has the advantages of non-cytotoxicity, good biocompatibility, easy absorption, small immune response, low antigenicity, etc. Coating titanium alloys with collagen promotes adhesion, proliferation, and differentiation of born-forming cells [30][31][32][33] as well as fibroblasts [34,35]. In comparison with uncoated commercially pure titanium, collagen coating significantly improves bone mineralization and maturation [36]. ...
Although titanium and titanium alloys have become the preferred materials for various medical implants, surface modification technology still needs to be strengthened in order to adapt to the complex physiological environment of the human body. Compared with physical or chemical modification methods, biochemical modification, such as the introduction of functional hydrogel coating on implants, can fix biomolecules such as proteins, peptides, growth factors, polysaccharides, or nucleotides on the surface of the implants, so that they can directly participate in biological processes; regulate cell adhesion, proliferation, migration, and differentiation; and improve the biological activity on the surface of the implants. This review begins with a look at common substrate materials for hydrogel coatings on implant surfaces, including natural polymers such as collagen, gelatin, chitosan, and alginate, and synthetic materials such as polyvinyl alcohol, polyacrylamide, polyethylene glycol, and polyacrylic acid. Then, the common construction methods of hydrogel coating (electrochemical method, sol–gel method and layer-by-layer self-assembly method) are introduced. Finally, five aspects of the enhancement effect of hydrogel coating on the surface bioactivity of titanium and titanium alloy implants are described: osseointegration, angiogenesis, macrophage polarization, antibacterial effects, and drug delivery. In this paper, we also summarize the latest research progress and point out the future research direction. After searching, no previous relevant literature reporting this information was found.
... One of the most common alkylsilane linkers is the silane coupling agent aminopropyl triethoxysilane (APTS), which has been used as a chemical linker to form a covalent bond between biomolecules, such as collagen and BMP-2, and titanium as the substrate. 85,86 Collagens covalently attached to implants in this manner have been shown to improve the proliferation and differentiation of human mesenchymal stem cells (hMSCs) into bone cells near the implants. 87 PEG is also used as a linker for biomolecule immobilization. ...
Surface biofunctionalization aims to create cell-instructive surfaces that control the behavior of cells and modulate cellular interactions by incorporating cell signaling moieties at the materials–biosystem interface. Despite advances in developing bioinert and biocompatible materials, blood clotting, inflammation, and cell death continue to be observed upon the contact of foreign materials with living tissues leading to the materials' rejection. Specific examples include the application of foreign materials in implantable devices (e.g., bone implants, antimicrobial surfaces, and cardiovascular stents), biosensors, drug delivery, and 3D-bioprinting. Biofunctionalization of materials to date has been predominantly realized using wet chemical approaches. However, the complexity of wet chemistry, toxicity of reactants, waste disposal issues, reaction time, poor reproducibility, and scalability drive a need for a paradigm shift from wet chemical approaches to dry methods of surface biofunctionalization. Plasma-based technologies that enable covalent surface immobilization of biomolecules have emerged as dry, reagent-free, and single-step alternatives for surface biofunctionalization. This review commences by highlighting the need for bioinstructive surfaces and coatings for various biomedical applications such as bone implants, antimicrobial surfaces, biosensors, and 3D-bioprinted structures, followed by a brief review of wet chemical approaches for developing biofunctionalized surfaces and biomimetic devices. We then provide a comprehensive review of the development of plasma-based technologies for biofunctionalization, highlighting the plasma–surface interactions and underpinning mechanisms of biomolecule immobilization.
... Grade V medical alloy (Ti6Al4V) discs (10 × 2 mm) were used as a Ti dental implant prototype in the study. 27 Sequential polishing of the discs was performed using 200 to 2,000 grit SiC abrasive sheets (3 M) and 1-micron oilbased diamond paste (Kemet, UK), to mimic the smooth surface of the neck of the implant and to provide a homogeneous surface for reactions. ...
GaN is an aqueous and chemically stable material that has demonstrated biocompatibility with potential in biomedical engineering and offers enormous opportunities to tailor its inherent surface properties and promote efficient biomolecule adhesion with targeted functionalities. In this article, functionalization of GaN surfaces via a three-step process to enhance cell attachment and its effective utilization in in-vivo and in-vitro applications is reported. The morphology and surface chemistry of GaN surfaces were modified using sodium hydroxide and 3-aminopropyltriethoxy silane followed via bioconjugation with type 1-human collagen (T1HC), and the changes in chemical states, morphology, wettability, pH, and aqueous stability were investigated. Further, cell culture studies using human periodontal ligament fibroblast (HPdlF) cells were undertaken. The proliferation and adhesion/survivability studies at different time intervals on functionalized GaN surfaces were performed and analyzed via MTT Assay and SEM evaluation. It has been observed that the hydroxyl species and protonated amines promoted the adhesion of the silane coupling agent and human collagen, which remains stable under standard cell culture media. The chemically functionalized T1HC bio-conjugated GaN surfaces display excellent cell culture properties with complete cell adhesion and viability of ∼ 95%. The research revealed that chemically functionalized GaN might be useful in various procedures where integrating soft tissues with implant surfaces is crucial.
... Grade V medical alloy (Ti6Al4V) discs (10 × 2 mm) were used as a Ti dental implant prototype in the study. 27 Sequential polishing of the discs was performed using 200 to 2,000 grit SiC abrasive sheets (3 M) and 1-micron oilbased diamond paste (Kemet, UK), to mimic the smooth surface of the neck of the implant and to provide a homogeneous surface for reactions. ...
Background: A weak implant-soft tissue interface may lead to bacterial ingres- sion, breakdown of underlying tissues, and eventually implant failure. This study proposes a surface modification technique of titanium alloy (Ti), using a nano- biopolymer scaffold to enhance soft tissue attachment in dental implants. Methods: Gelatin (20% w/v) embedded with 10 ± 2 nm silver nanoparticles (AgNPs) was electrospun to form a gelatin electrospun mat (GEM) scaffold, bonded to Ti alloy surface using chemical surface functionalization. Antimicro- bial activity of AgNPs was tested against representative Gram-positive (Staphy- lococcus aureus) and Gram-negative bacteria (Escherichia coli) at 4, 24, and 48 hours and after embedding in scaffold at 48 hours. Cytotoxicity analysis (MTT assay) was performed using the 3T3 mouse fibroblast cell line at 24 and 72 hours for two groups: control (unmodified Ti disc) and experimental (GEM embedded with AgNPs); and further validated by scanning electron microscopy.
Results: The AgNPs-embedded GEM showed good antimicrobial activity at 48 hours, with the AgNPs showing complete (99.99%) inhibition of bacterial colony counts at 24 and 48 hours. Cell viability and proliferation over the GEM mod- ified Ti discs were seen to be significantly increased (P < 0.05) at 72 hours as compared with control. SEM images revealed intimate spreading of fibroblasts, with differentiated cell morphology and pseudopodial processes, indicative of enhanced fibroblastic adhesion, growth, and differentiation over the scaffold. Conclusion: Results show good antifouling properties and biocompatibility of the fabricated coating, making it a promising strategy to reduce postoperative infections and peri-implant diseases in Ti dental implants.
KEYWORDS
antimicrobial(s), biomaterial(s), fibroblast(s), implantology, tissue engineering
... BA has shown excellent antiinflammatory and bone tissue regenerating properties in the treatment of periodontitis 17,18) . In addition, studies have shown that BA is effective in enhancing fibroblast activity and inducing the expression of collagen, which played an important role in promoting cell adhesion, spread, growth and tissue regeneration [19][20][21][22] . Studies also reveal that BA facilitates cell adhesion and migration via upregulating the expression of adhesion-related proteins, including integrin α5 and integrin β1 23) . ...
After periodontal tissue injury, reconstruct soft tissue sealing around the tooth surface is of fundamental importance to treat periodontitis. Among multiple cell types, fibroblast plays a central role in reestablishing functional periodontium. To enhance fibroblast activity, a novel metal-organic framework-based nanoplatform is fabricated using mesoporous Prussian blue (MPB) nanoparticles to load baicalein (BA), named MPB-BA. Drug release test displayed sustained BA release of MPB-BA. Cell proliferation, transwell migration and wound healing tests revealed accelerated fibroblast proliferation and migration for the established MPB-BA nanoplatform. Moreover, vinculin immunofluorescence staining, western blot and quantitative real-time PCR analysis showed up-regulated vinculin protein and integrin α5 and integrin β1 gene expressions for MPB-BA, suggesting improved cell adhesion. In addition, hematoxylin and eosin (H&E) and Masson trichromatic staining suggested superior anti-inflammatory and collagen fiber reconstruction effects for MPB-BA in a rat experimental periodontitis model in vivo. Our study may provide a promising strategy for the treatment of periodontitis.
... More recently, implants with dual-etched, collagen-coated surfaces have confirmed the enhancing effect of this type of coating on osseointegration [11][12][13]. Binding of collagen to titanium and titanium alloy surfaces has also shown to improve soft tissue biocompatibility in vitro and in vivo [14][15][16][17]. ...
The aim of the present study was to develop a collagen/heparin-based multilayer coating on titanium surfaces for retarded release of recombinant human bone morphogenic protein 2 (rhBMP2) to enhance the osteogenic activity of implant surfaces. Polyelectrolyte multilayer (PEM) coatings were constructed on sandblasted/acid-etched surfaces of titanium discs using heparin and collagen. PEM films of ten double layers were produced and overlayed with 200 µL of a rhBMP2 solution containing 15 µg rhBMP2. Subsequently, cross-linking of heparin molecules was performed using EDC/NHS chemistry to immobilize the incorporated rhBMP2. Release characteristics for 3 weeks, induction of Alkaline Phosphatase (ALP) in C2C12 cells and proliferation of human mesenchymal stem cells (hMSCs) were evaluated to analyze the osteogenic capacity of the surface. The coating incorporated 10.5 µg rhBMP2 on average per disc and did not change the surface morphology. The release profile showed a delivery of 14.5% of the incorporated growth factor during the first 24 h with a decline towards the end of the observation period with a total release of 31.3%. Cross-linking reduced the release with an almost complete suppression at 100% cross-linking. Alkaline Phosphatase was significantly increased on day 1 and day 21, indicating that the growth factor bound in the coating remains active and available after 3 weeks. Proliferation of hMSCs was significantly enhanced by the non-cross-linked PEM coating. Nanocoating using collagen/heparin-based PEMs can incorporate clinically relevant amounts of rhBMP2 on titanium surfaces with a retarded release and a sustained enhancement of osteogenic activity without changing the surface morphology.
... Regarding the material characteristics, a high level of biocompatibility can be expected for the investigated 3D retainer because of the titanium grade 5 material [32]. This could be a good alternative for patients with nickel allergies. ...
Objectives
New opportunities have arisen to manufacture three-dimensional computer-aided design/computer-aided manufacturing (3D CAD/CAM) retainers from titanium blocks by digital cutting technology. These novel technologies need to fulfill requirements regarding digital planning and position accuracy. The aim of the present study was to investigate the digital construction, the CAD/CAM production and the intraoral positioning accuracy of custom-manufactured novel 3D CAD/CAM titanium retainers.
Materials and methods
A total of 37 prime4me® RETAIN3R (Dentaurum, Ispringen, Germany) retainers were inserted to stabilize the upper anterior front teeth. Following insertion, an intraoral scan was used to record the position. The intraoral position was compared to the virtual setup using 3D superimposition software. Measurement points were evaluated in all three dimensions (horizontal, sagittal and vertical planes). Data were analyzed using Kruskal–Wallis test followed by Dunn’s multiple comparison test.
Results
A total of 185 measurements were performed. The horizontal plane and the sagittal plane demonstrated a high level of positioning accuracy between the planned and the intraoral position. Statistically significant deviations between the preceding virtual setup and the intraoral situation were observed in the vertical dimension. Within the retainer, the intraoral positioning accuracy decreased for the measurement points in the direction of the distal retainer segment.
Conclusion
Based on the results, the present study shows a high level of congruence between the 3D virtually planning and the final intraoral position of the fabricated novel 3D CAD/CAM titanium retainers.
... These compounds are usually prepared in advance and used as bone cement or applied as a surface layer covering the implant [105][106][107][108][109], although it is also possible to induce its growth on the substrate surface [110][111][112]. In the latter case, the thin layer that constitutes the coating acts as a messenger through which interaction with the surrounding biological system occurs [113][114][115]. The outer layer of the device should be compromised of compounds naturally present in the biological environment, commonly calcium phosphate phases [116][117][118][119]. ...
Metal phosphates represent an important group of materials with established industrial applications that are still attracting special scientific interest, owing to their outstanding physical and chemical properties. In this review, we account on the different synthetic routes and applications of zirconium and titanium phosphates, with a special focus on their application in the medicinal field. While zirconium phosphate has been extensively studied and explored with several reported industrial and medicinal applications, especially for drug delivery applications, titanium phosphates have not yet attracted the deserved attention regarding their established applications. However, titanium phosphates have been the focus of several structural studies with their different polymorphic forms, varied chemical structures, and morphologies. These variations introduce titanium phosphates as a strong candidate for technological and, particularly, biomedical applications.
... Peaks observed at 3322 cm -1 and 2936 cm -1 were assigned to symmetric and asymmetric stretching modes of -NH 2 and stretching mode of -CH 2 , respectively [45]. Double peaks at 1482 cm -1 and 1572 cm -1 corresponded to -N-H bending vibration, and -C-H vibration mode corresponded to 1314 cm -1 [46,47]. ...
Durable, biocompatible and interphases composed of interpenetrating network of alginate and gelatin (A/G) with long shelf-life were produced. Titanium implants were conditioned with acid:peroxide followed by sodium hydroxide (NaOH) etching. Surfaces were grafted with 3-aminopropyl triethoxysilane (APTES) and optimized. It was hypothesized that interpenetrating network of A/G coated on Ti-APTES in the presence of 0.2 M sodium chloride could improve the adhesive strength and create a highly cohesive hydrogel interphase. Optimized A/G ratio and APTES grafting procedure allowed us to reproducibly produce a layer which resulted in a gap-filling, seamless and robust coating that can assume implant shape, maintain morphology and stay intact for a year at room temperature. Especially A/G 1:3 interphase coating (16.41 ± 0.34 μm) demonstrated good adhesion (1.28 ± 0.32 N), water uptake (589% ± 78), hydrolytic degradation (63 ± 1%), low initial wettability in simulated body fluid, but demonstrated rapid methylene blue (MB) uptake (80% of drug within 1 h) and burst release (100% of MB within ∼3h), and favored osteoblast adhesion and proliferation over time. Furthermore, A/G 1:3 maintained integrity and showed minimal loss of strength over 12 months. Hence, A/G 1:3 interphase showed substantial potential to improve biofunctionality of bioinert implants.
... Grade V medical alloy (Ti6Al4V) discs (10 × 2 mm) were used as a Ti dental implant prototype in the study. 27 Sequential polishing of the discs was performed using 200 to 2,000 grit SiC abrasive sheets (3 M) and 1-micron oilbased diamond paste (Kemet, UK), to mimic the smooth surface of the neck of the implant and to provide a homogeneous surface for reactions. ...
Background:
A weak implant-soft tissue interface may lead to bacterial ingression, breakdown of underlying tissues, and eventually implant failure. This study proposes a surface modification technique of titanium alloy (Ti), using a nano-biopolymer scaffold to enhance soft tissue attachment in dental implants.
Methods:
Gelatin (20% w/v) embedded with 10±2 nm silver nanoparticles (AgNPs) was electrospun to form a Gelatin Electrospun Mat (GEM) scaffold, bonded to Ti alloy surface using chemical surface functionalization. Antimicrobial activity of AgNPs was tested against representative Gram-positive (S. aureus) and Gram-negative bacteria (E. coli) at 4, 24, and 48 hours (h) and after embedding in scaffold at 48 h. Cytotoxicity analysis (MTT assay) was carried out using the 3T3 mouse fibroblast cell line at 24 and 72 h for two groups: Control (unmodified Ti disc) and Experimental (GEM embedded with AgNPs); and further validated by scanning electron microscopy (SEM).
Results:
The AgNPs-embedded GEM showed good antimicrobial activity at 48 h, with the AgNPs showing complete (99.99%) inhibition of bacterial colony counts at 24 h and 48 h. Cell viability and proliferation over the GEM modified Ti discs were seen to be significantly increased (p < 0.05) at 72 h as compared to control. SEM images revealed intimate spreading of fibroblasts, with differentiated cell morphology and pseudopodial processes, indicative of enhanced fibroblastic adhesion, growth, and differentiation over the scaffold.
Conclusion:
Results show good antifouling properties and biocompatibility of the fabricated coating, making it a promising strategy to reduce post-operative infections and peri-implant diseases in Ti dental implants. This article is protected by copyright. All rights reserved.
... Biomaterials for nerve, bone/cartilage and tendon/ligament [351,352] Orthopedic implants, Bone tissue regeneration, dental, vascular stent [353][354][355][356] Bone tissue regeneration, vascular stents [357][358][359] Hyaluronan Osteoarthritis Treatment, dermal Filler, bone regeneration, wound repair, epithelial tissue, and neural tissue repair [360,361] Orthopedic implants [362][363][364] Bone tissue regeneration, Orthopedic implants [363,365] Chondroitin sulfat e In vivo: drastic elevation of osteocalcin expression, prominent bone formation in a rat model [461] J o u r n a l P r e -p r o o f ...
The review encompasses state-of-the-art strategies for design and fabrication of smart biomaterials for tissue engineering. The focus of the work is mainly put on metallic biomaterials with hybrid coatings consisting of bioceramic and polymeric layers with hierarchical organization and drug-eluting capacity.
Key technologies and steps to design hybrid smart and multifunctional coatings on metallic cores for bone regeneration implants and cardiovascular stents are outlined, including additive manufacturing of titanium and magnesium alloys for permanent and temporary implant applications. Three levels of hierarchical surface functionalization are described: i) in situ modification of the core material, incorporating bioactive inorganic species and phases by means of ceramic coatings via anodic electrochemical treatments; ii) post-treatment application of polymer layers, monolithic or with specific porous breath figure topography; and iii) application of a cellular therapy component (single cell or cell sheet). Recent progress in incorporation of drug-eluting functionality into such materials via direct or nanocarrier-assisted loading is also highlighted.
... Covalent attachment of collagen and fibronectin to TiO 2 has been widely investigated using both silane and phosphonate chemistries to alter the chemical and morphological properties of the surface of biomedical implants, and to improve osseointegraton [126][127][128][129]. While short-term interfacial stability has been reported in some cases, no studies of stability have been reported in a biosensor format. ...
Electrochemical biosensors have potential applications for agriculture, food safety, environmental monitoring, sports medicine, biomedicine, and other fields. One of the primary challenges in this field is the immobilization of biomolecular probes atop a solid substrate material with adequate stability, storage lifetime, and reproducibility. This review summarizes the current state of the art for covalent bonding of biomolecules onto solid substrate materials. Early research focused on the use of Au electrodes, with immobilization of biomolecules through ω-functionalized Au-thiol self-assembled monolayers (SAMs), but stability is usually inadequate due to the weak Au–S bond strength. Other noble substrates such as C, Pt, and Si have also been studied. While their nobility has the advantage of ensuring biocompatibility, it also has the disadvantage of making them relatively unreactive towards covalent bond formation. With the exception of Sn-doped In2O3 (indium tin oxide, ITO), most metal oxides are not electrically conductive enough for use within electrochemical biosensors. Recent research has focused on transition metal dichalcogenides (TMDs) such as MoS2 and on electrically conductive polymers such as polyaniline, polypyrrole, and polythiophene. In addition, the deposition of functionalized thin films from aryldiazonium cations has attracted significant attention as a substrate-independent method for biofunctionalization.
... Functionalization of implant surfaces with bioactive molecules offers a tempting solution for overcoming slow peri-implant bone regeneration via immunomodulation, presentation of cell-instructive cues, and prevention of biofilm formation [12][13][14]. A variety of bioactive molecules including proteins [15][16][17][18][19], nucleotides [20,21], peptides [22][23][24], and antimicrobial agents [25][26][27] have been immobilized to functionalize titanium implants. However, these coatings typically display a single biofunction, which may not offer sufficient simultaneous or sequentially-controlled concerted relief against biofilm formation and slow bone regeneration. ...
Functionalization of dental and orthopaedic implants with multiple bioactivities is desirable to obtain surfaces with improved biological performance and reduced infection rates. While many approaches have been explored to date, nearly all functionalized surfaces are static, i.e., non-responsive to biological cues. However, tissue remodeling necessary for implant integration features an ever-changing milieu of cells that demands a responsive biomaterial surface for temporal synchronization of interactions between biomaterial and tissue. Here, we successfully synthesized a multi-functional, dynamic coating on titanium by co-immobilizing GL13K antimicrobial peptide and an MMP-9 – a matrix metalloproteinase secreted by bone-remodelling osteoclasts – responsive peptide. Our co-immobilized peptide surface showed potent anti-biofilm activity, enabled effective osteoblast and fibroblast proliferation, and demonstrated stability against a mechanical challenge. Finally, we showed peptide release was triggered for up to seven days when the multi-peptide coatings were cultured with MMP-9-secreting osteoclasts. Our MMP-9 cleavable peptide can be conjugated with osteogenic or immunomodulatory motifs for enhanced bone formation in future work. Overall, we envisage our multifunctional, dynamic surface to reduce infection rates of percutaneous bone-anchored devices via strong anti-microbial activity and enhanced tissue regeneration via temporal synchronization between biomaterial cues and tissue responses.
... It was reported that titanium alloy grade V was functionalized with human collagen for promoting the fibroblast adhesion, which resulted in ameliorating the tissue-implant interactions [17,18]. Epidermal keratinocytes and dermal fibroblasts were cultured simultaneously on nanostructured titanium. ...
There have been several attempts to improve the cellular and molecular interactions at the tissue–implant interface. Here, the biocompatibility of titanium-based implants (e.g., Grade 2 Titanium alloy (Ti-40) and titanium–niobium alloy (Ti-Nb)) has been assessed using different cellular and molecular examinations. Cell culture experiments were performed on three substrates: Ti-40, Ti-Nb, and tissue culture polystyrene as control. Cells number and growth rate were assessed by cell counting in various days and cell morphology was monitored using microscopic observations. The evaluation of cells’ behavior on the surface of the implants paves the way for designing appropriate biomaterials for orthopedic and dental applications. It was observed that the cell growth rate on the control sample was relatively higher than that of the Ti-40 and Ti-Nb samples because of the coarse surface of the titanium-based materials. On the other hand, the final cell population was higher for titanium-based implants; this difference was attributed to the growth pattern, in which cells were not monolayered on the surface. Collagen I was not observed, while collagen III was secreted. Furthermore, interleukin (IL)-6 and vascular endothelial growth factor (VEGF) secretion were enhanced, and IL-8 secretion decreased. Moreover, various types of cells can be utilized with a series of substrates to unfold the cell behavior mechanism and cell–substrate interaction.
... BMP-2, known to stimulate cortical bone formation in surgical procedures [68][69][70], has been immobilized on Ti surfaces and found to stimulate the proliferation and differentiation of bone marrow stem cells and osteoblast-like cells [71][72][73][74][75]. Cell Table 1 Properties of bone, PEEK, Ti and its alloys applied for the fabrication of bone implants. The values for the mechanical properties are obtained from [27,29,52,53] adhesion proteins, including fibronectin [76], collagen [77][78][79], tropoelastin [80], silk fibroin (SF) [81][82][83], and sericin [84], are proteins immobilized to facilitate the indirect formation of bone tissue. These proteins create ECM adhesion sites allowing osteoblastic cells to attach and initiate the osseointegration process [85,86]. ...
Orthopedic implants are increasing in global prevalence, with hundreds of thousands of operations performed annually. However, a significant proportion of these operations experiences failure due to poor bone integration. Many avenues of investigation have been explored to address this issue and improve the biocompatibility of orthopedic devices by modifying the biological response to the implant surface. Biomimetic functionalization of orthopedic surfaces enables control over the biological response by signaling through immobilized proteins and other biomolecules. This approach seeks to promote osteoblast differentiation and bone formation at the implant surface, leading to integration between the orthopedic surface and the local bone tissue. This review commences by highlighting the need for biomimetic functionalization from a materials and biological perspective. The surface properties that govern protein-surface interactions are subsequently explained. Progress in biomolecule functionalization of orthopedic surfaces performed via adsorption, chemical covalent immobilization, and physical covalent immobilization are discussed and reviewed. The immobilization mechanisms for each approach are examined and the strategies are evaluated according to their complexity, efficacy, reproducibility, and scalability. Emerging and prospective avenues for the transition from 2D to 3D substrates and the multi-functionalization of biomimetic surfaces are then explored.
... An easy and cost-effective strategy to overcome this issue involves modifying the metallic surface, as doing so allows the composition, structure, and morphology of the material to be varied without altering the excellent mechanical properties of the bulk material [4,5]. Promising results have been reached with coatings containing biopolymers such as poly(lactic acid) [6,7] and biological molecules like type I human collagen [8,9]. In this context, sol-gel technology has geared the attention because coatings can be prepared with an easy and low energyconsuming procedure [10][11][12]. ...
Sol-gel coatings are proposed as surface treatments for titanium-based materials to promote the osseointegration of prosthetic devices with the host. As precursors of sol-gel synthesis, two silanes were selected: 3-methacryloxypropyltrimethoxy silane and 2 tetramethyl orthosilane. Sol-gel synthesis was functionalized with the addition of two different organophosphorus compounds, namely, tris(trimethylsilyl) phosphite and tris(trimethylsilyl) phosphate. Depending on the organophosphorus compound, phosphorus was incorporated into the sol-gel network by different mechanisms: organophosphate was incorporated following a hydrolysis/polycondensation reaction with the precursors of synthesis (two organopolysiloxanes), whereas organophosphite was introduced into the network through transformation of trivalent phosphorus to pentavalent phosphorus following a Michaelis-Arbuzov reaction and subsequent reaction of hydrolysis/polycondensation. When compared to the control coating, which has good adhesion coating-substrate, only the addition of the organophosphite ensured good adhesion without altering synthesis. The resulting coating modified with organophosphite was subjected to cellular study and the concentration of this compound was varied to reach the highest enhancement of proliferation. It was demonstrated that by increasing the amount of organophosphite cell proliferation increased. Inspection of the surfaces of the coatings revealed that by increasing the quantity of organophosphite, adhesion to the substrate was compromised. Thus, an intermediate quantity of organophosphite was considered the most suitable for application on metallic prosthetic devices.
... FT-IR is commonly used for characterization of chemical groups existing over different substrates, and it has been demonstrated to be also useful for Ti6Al4V characterization [39,40]. Figure 1 shows the FT-IR spectra for untreated and treated titanium alloy parts at 0˚ polarization, which was found the optimal one to highlight the differences among treatments. ...
Different treatments were conducted over Ti6Al4V samples in order to produce a surface modification to increase cell attachment and proliferation. The surface treatments evaluated in this study were as follows: etching with sulfuric acid/hydrochloric acid, oxidizing with hydrogen peroxide and low-pressure oxygen plasma treatment. In contrast to other works found in the literature, this research conducts a comparison between different chemical and physical treatments in terms of different assays for surface characterization: X-ray diffraction, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy, water contact angle, release of vanadium ions and cell viability tests (MTT) of human osteoblasts (hFOB 1.19). Cell morphology over the different substrates was also studied by SEM observation. It was found that plasma and peroxide treatments increase the O/Ti ratio at the titanium surface and provide an increase in cell affinity. On the other hand, acid etching provides a superhydrophilic surface which is not able to improve the cell attachment of human osteoblasts.
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... Adsorption methods are easy to perform, but the protein molecules experience competitive adsorption−desorption when placed in the biological environment in a process often referred to as the Vroman effect. 15−17 Permanent surface-immobilization of proteins has been achieved using chemical linkers, such as polydopamine (DOPA) 18 and silanes, 19,20 covalently anchored to the surface. However, wet-chemistry methods applied for covalent protein functionalization are typically time-consuming 21−23 and produce side-reactions that reduce the immobilization efficiency and limit reproducibility. ...
Osseointegration is essential for ensuring optimal functioning and longevity of orthopedic implants. In a significant number of patients, the body does not fully integrate with the orthopedic implant, which opens the potential for the formation of bacterial biofilms and adverse foreign body reactions. Protein-functionalization of the implant surfaces can reduce this potential by stimulating rapid cell attachment or bone formation. Ideally, a multifunctional protein surface should simultaneously stimulate cell attachment and bone formation for optimal osseointegration. In this study, we utilized primary mouse osteoblasts to examine the osteogenic potential of a multifunctional fusion protein, combining the fibronectin (FN) attachment and osteocalcin (OCN) bone signaling sequences, compared against that of the individual proteins. These three biomolecules were immobilized on radical-functionalized plasma polymer films (rPPFs) that covalently bond proteins through interactions with embedded radicals that migrate to the surface. The fusion protein was also compared to a coimmobilized ratio of FN:OCN prepared through a two-step sequential exposure to OCN solution followed by FN solution. The preparation and characterization overhead for the two protein surfaces was substantial when compared to the fusion protein functionalization process. Significantly greater osteoblast attachment and spreading were observed for the FN, FN:OCN, and fusion protein surfaces compared to titanium (p < 0.05), while the calcium deposition after 17 days showed a significant increase (p < 0.01) on the fusion protein surface alone. The greater osseointegration potential of the fusion protein surface compared to the single and coimmobilized protein surfaces is attributed to the homogeneous distribution of the attachment and signaling sequences. Overall, the fusion protein-coated rPPFs produced easily functionalizable and highly osteogenic surfaces with the potential to greatly improve the tissue integration of orthopedic implants.
Along with poor implant-bone integration, peri-implant diseases are the major causes of implant failure. Although such diseases are primarily triggered by biofilm accumulation, a complex inflammatory process in response to corrosive-related metallic ions/debris has also been recognized as a risk factor. In this regard, by boosting the titanium (Ti) surface with silane-based positive charges, cationic coatings have gained increasing attention due to their ability to kill pathogens and may be favorable for corrosion resistance. Nevertheless, the development of a cationic coating that combines such properties in addition to having a favorable topography for implant osseointegration is lacking. Because introducing hydroxyl (-OH) groups to Ti is essential to increase chemical bonds with silane, Ti pretreatment is of utmost importance to achieve such polarization. In this study, plasma electrolytic oxidation (PEO) was investigated as a new route to pretreat Ti with OH groups while providing favorable properties for implant application compared with traditional hydrothermal treatment (HT). To produce bactericidal and corrosion-resistant cationic coatings, after pretreatment with PEO or HT (Step 1), surface silanization was subsequently performed via immersion-based functionalization with 3-aminopropyltriethoxysilane (APTES) (Step 2). In the end, five groups were assessed: untreated Ti (Ti), HT, PEO, HT+APTES, and PEO+APTES. PEO created a porous surface with increased roughness and better mechanical and tribological properties compared with HT and Ti. The introduction of -OH groups by HT and PEO was confirmed by Fourier transform infrared spectroscopy and the increase in wettability producing superhydrophilic surfaces. After silanization, the surfaces were polarized to hydrophobic ones, and an increase in the amine functional group was observed by X-ray photoelectron spectroscopy, demonstrating a considerable amount of positive ions. Such protonation may explain the enhanced corrosion resistance and dead bacteria (Streptococcus aureus and Escherichia coli) found for PEO+APTES. All groups presented noncytotoxic properties with similar blood plasma protein adsorption capacity vs the Ti control. Our findings provide new insights into developing next-generation cationic coatings by suggesting that a tailorable porous and oxide coating produced by PEO has promise in designing enhanced cationic surfaces targeting biomedical and dental implant applications.
Polyetheretherketone (PEEK) is a biocompatible material widely used in spinal and craniofacial implants, with potential use in percutaneous implants. However, its inertness prevents it from forming a tight seal with the surrounding soft tissue, which can lead to infections and implant failure. Conversely, the surface chemistry of percutaneous organs (i.e., teeth) helps establish a strong interaction with the epithelial cells of the contacting soft tissues, and hence a tight seal, preventing infection. The seal is created by adsorption of basement membrane (BM) proteins, secreted by epithelial cells, onto the percutaneous organ surfaces. Here, we aim to create a tight seal between PEEK and epithelial tissues by mimicking the surface chemistry of teeth. Our hypothesis is that collagen I, the most abundant tooth protein, enables integration between the epithelial tissue and teeth by promoting adsorption of BM proteins. To test this, we immobilized collagen I via EDC/NHS coupling on a carboxylated PEEK surface modified using diazonium chemistry. We used titanium alloy (Ti-6Al-4V) for comparison, as titanium is the most widely used percutaneous biomaterial. Both collagen-modified PEEK and titanium showed a larger adsorption of key BM proteins (laminin, nidogen, and fibronectin) compared to controls. Keratinocyte epithelial cell viability on collagen-modified PEEK was twice that of control PEEK and ∼1.5 times that of control titanium after 3 days of cell seeding. Both keratinocytes and fibroblasts spread more on collagen-modified PEEK and titanium compared to controls. This work introduces a versatile and biomimetic surface modification technique that may enhance PEEK-epithelial tissue sealing with the potential of extending PEEK applications to percutaneous implants, making it competitive with titanium.
Dental implants have been widely accepted as an ideal therapy to replace the missing teeth for its good performance in aspects of mechanical properties and aesthetic outcomes. Its restorative success is contributed by not only the successful osseointegration of the implant but also the tight soft tissue integration, especially the collagen fibers, in the transmucosal region. Soft tissue attaching to the dental implant/abutment is overall similar, but in some aspects distinct with that seen around natural teeth and soft tissue integration can be enhanced via several surface modification methods. This review is going to focus on the current knowledge of the transmucosal zone around the dental implants (compared with natural teeth), and latest strategies in use to fine-tune the collagen fibers assembly in the connective tissue, in an attempt to enhance soft tissue integration.
Titanium (Ti) implants are bioinert materials. The surface modification of a Ti implant can endow it with biological activity and promote its osteosynthesis. In this study, the improvement of the biocompatibility of Ti substrates mainly originates from polydopamine (PDA) coating technology, which combines the BMP‐2 polypeptide (P24) and a gelatin film on the substrate surface. The results showed that the P24 polypeptide and gelatin film coating endowed the Ti substrate with enhanced hydrophilicity. The modified surface favored cell adhesion and spreading compared with the pure Ti substrate, and significantly improved cell proliferation and osteogenic differentiation of bone marrow stem cells (BMSCs) in vitro. Furthermore, the modification significantly accelerated osseointegration and osteogenesis in vivo when the Ti rod was inserted into rat femurs. Thus, the P24 polypeptide and gelatin film modification on titanium implant surface has potential applications to achieve rapid bone‐implant integration.
Titanium implants are widely used in traumatology and various orthopedic fields. Titanium and other metallic-based implants have limited structural and functional integration into the body, which translates into progressive prosthesis instability and the need for new surgical interventions that have enormous social and economic impacts. To enhance the biocompatibility of titanium implants, numerous biofunctionalization strategies have been developed. However, the problem persists, as more than 70% of implant failures are due to aseptic loosening. In this study we addressed the problem of improving the physiological engraftability and acceptability of titanium-based implants by applying a robust and versatile functionalization method based on the covalent immobilization of extracellular matrix (ECM)-derived oligopeptides on Ti-6Al-4V surfaces treated by activated vapor silanization (AVS). The feasibility of this technique was evaluated with two oligopeptides of different structures and compositions. These oligopeptides were immobilized on Ti-6Al-4V substrates by a combination of AVS and N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) crosslinking chemistry. The immobilization was shown to be stable and resistant to chemical denaturing upon sodium dodecyl sulfate treatment. On Ti-6Al-4V surfaces both peptides increased the attachment, spreading, rearrangement and directional growth of mesenchymal stem and progenitor cells (MSC) with chondro- and osteo-regenerative capacities. We also found that this biofunctionalization method (AVS-EDC/NHS) increased the attachment capacity of an immortalized cell line of neural origin with poor adhesive properties, highlighting the versatility and robustness of this method in terms of potential oligopeptides that may be used, and cell lineages whose anchorage to the biomaterial may be enhanced. Collectively, this novel functionalization strategy can accelerate the development of advanced peptide-functionalized metallic surfaces, which, in combination with host or exogenously implanted stem cells, have the potential to positively affect the osteoregenerative and osteointegrative abilities of metallic-based prostheses.
Titanium (Ti) has excellent biocompatibility and corrosion resistance and is widely used as a biomedical material for orthopedic implants. However, the bare Ti surface limits cell adhesion without biological activity and promotes unnecessary protein adsorption, which can activate the coagulation pathway with blood-contacting devices. To improve the antifouling and biological activity of Ti, zwitterionic poly[2-(methacryloyloxy)ethyl choline phosphate] (PMCP) was used to modify the Ti surface via surface-initiated atom transfer radical polymerization. The Ti-PMCP surface reduced bovine serum albumin and fibrinogen adsorption owing to the zwitterionic antifouling property. Ti-PMCP is involved in the unique interaction between PMCP on the Ti surface and phosphate choline on cell membranes, and therefore, the Ti-PMCP surface can promote the adhesion and proliferation of MC3T3-e1 cells and bone marrow mesenchymal cells (BMSCs). In addition, the Ti-PMCP surface was effective in promoting the osteogenic differentiation of MC3T3-e1 cells and BMSCs because the phosphate group in MCP can stimulate osteogenic signaling pathways. Therefore, the PMCP-modified Ti surface can resist protein adsorption and promote the adhesion, proliferation, and differentiation of osteoblast-related cells and has great potential in bone tissue engineering.
Biomaterials and their surfaces regulate the biological response and ultimately the quality of healing at a possible site of implantation. The physical, chemical and topographical properties of implants' surfaces play a decisive role in the biological integration process for their immediate loading and long-term success. Since at this level of biological interaction nano-dimensionality is basically entailed, bio-functional nanostructured composites either as filling/cement or coating to metallic implants are required. This study shows the possibility of synthesizing two phases of nanostructured titanium phosphate (π and ρ polymorphs) and enriching them with silver nanoparticles and strontium. More importantly, Ag-Sr-enriched nanostructured π‑titanium phosphate is induced to grow on a commercially available titanium alloy (Ti-6Al-4 V), widely used in orthopedic and dental implants, under highly controlled conditions. Structural and microscopic observations, using XRD, HRTEM and SEM altogether confirm the resultant phases and their enrichment with strontium and silver nanoparticles with an average particle size around 6 nm. Using confocal laser scanning microscopy, the surface roughness was measured and is found to lay at the interface between the nanosized and micro sized topologies. Ion release assessments showed that the presence of strontium controlled the release rate of silver ions and this could be beneficial in terms of decreasing the accompanied cytotoxicity that is usually encountered at high concentrations of silver. Antimicrobial and cell proliferation assays have proved that enriching titanium phosphate with strontium and silver nanoparticles has improved their antimicrobial properties, while the cytotoxicity could be controlled.
Dental clinicians have relied for centuries on traditional dental materials (polymers, ceramics, metals, and composites) to restore oral health and function to patients. Clinical outcomes for many crucial dental therapies remain poor despite many decades of intense research on these materials. Recent attention has been paid to biomolecules as a chassis for engineered preventive, restorative, and regenerative approaches in dentistry. Indeed, biomolecules represent a uniquely versatile and precise tool to enable the design and development of bioinspired multifunctional dental materials to spur advancements in dentistry. In this review, we survey the range of biomolecules that have been used across dental biomaterials. Our particular focus is on the key biological activity imparted by each biomolecule toward prevention of dental and oral diseases as well as restoration of oral health. Additional emphasis is placed on the structure-function relationships between biomolecules and their biological activity, the unique challenges of each clinical condition, limitations of conventional therapies, and the advantages of each class of biomolecule for said challenge. Biomaterials for bone regeneration are not reviewed as numerous existing reviews on the topic have been recently published. We conclude our narrative review with an outlook on the future of biomolecules in dental biomaterials and potential avenues of innovation for biomaterial-based patient oral care.
Commercially pure titanium and titanium alloys have been extensively used for designing musculoskeletal implants due to their biocompatibility and mechanical properties. The clinical success of these implants relies on supporting favorable osteoimmune environment, which then regulates bone regeneration and evades bacterial infection. Several surface engineering strategies have been employed to impart multifunctional properties to the otherwise bioinert titanium and titanium alloys. This chapter outlines these strategies, which encompass physical and chemical modification and their downstream effects on cell responses. In particular, we introduce the effect of these modifications on cells from hard and soft tissue along with their antibacterial properties and immune-modulatory effects. This chapter provides an up-to-date summary of where we are and how the understanding of the cellular response in vitro can help up drive the implant design for effective tissue repair and regeneration in clinical scenarios.
The clinical success of a titanium (Ti) percutaneous implant requires the integration with soft tissues to form a biological seal, which effectively combats marsupialization, premigration and infection after implantation. However, the bioinert surface of Ti or its alloys prevents the material from sufficient biological sealing and limits the application of Ti or its alloys as percutaneous implants. In this study, we achieved a collagen coating to bioactivate the surface of Ti-6Al-4V. In order to enable covalent functionalization, we first deposited a polydopamine (PDA) coating on Ti-6Al-4V based on dopamine self-polymerization and then immobilized collagen chains on PDA. Compared with physical absorption, such a chemical bonding method through mussel-inspired chemistry showed better stability of the coating. Meanwhile, the cellular tests in vitro indicated that collagen functionalization on the Ti-6Al-4V surface showed better adhesion of human foreskin fibroblasts (HFFs) and human immortal keratinocytes (HaCaTs). The subcutaneous implantation tests in rats indicated that the collagen modification attenuated soft tissue response and improved tissue compatibility compared with either pure Ti-6Al-4V or merely PDA coated samples. The facile bioinspired approach enables a persistent modification of metals by macromolecules under aqueous environments, and the PDA-collagen coated titanium alloy is worthy of further investigation as a percutaneous implant.
Currently titanium and its alloys are the metal of choice in medical and dental applications due to their improved mechanical and chemical properties like excellent corrosion resistance, high specific strength and light weight. In this review, the literature was screened for studies on various aspects of surface modifications techniques (mechanical, physical, chemical, biological and any combinations) for titanium and its alloys to make it more biocompatible for biomedical applications. Technical aspects of such techniques and their modifications are being discussed along with the surface features of the modified titanium alloys. Using appropriate surface modification method, it is possible to expand the arena of biomedical application of titanium and its alloys for long term uses while retaining the most of the desired features which make it a clinical success.
Achieving long term osseointegration is fundamental for the development of successful bone implants. A key aspect for improving long term osseointegration on titania surfaces is to gain control of nano and microscale features. The so called biological approach is applied here to modify the surface of titania based on coating it with a self-assembled and chemically crosslinked biopolymer film made from alginate and collagen. The biofilm coated titania closely mimics the bone extracellular matrix regarding bio-morphology and mechanical properties. Biofilms are prepared using the layer by layer technique combined with carbodiimide chemistry to achieve a stable and compact structure. Alginate-collagen coatings display fibrillar morphology with an apparent fiber diameter of ~50 nm and lengths ranging from a few hundred nanometers to ~3 [small mu ]m, mimicking therefore, the extracellular matrix of the bone in fiber length and extent. Atomic Force Spectroscopy revealed a Young's modulus of a few kPa for the film, which matches the mechanical properties of naturally occurring collagen fibers. Osteoblast MC3T3-E1 cells showed enhanced adhesion on the coated surface compared to the bare titania, and a superior biological activity of the alginate-terminated coating that interfaces the cells in biological fluids.
The development of biomaterials for cardiac tissue engineering (CTE) is challenging, primarily owing to the requirement of achieving a surface with favourable characteristics that enhances cell attachment and maturation. The biomaterial surface plays a crucial role as it forms the interface between the scaffold (or cardiac patch) and the cells. In the field of CTE, synthetic polymers (polyglycerol sebacate, polyethylene glycol, polyglycolic acid, poly-l-lactide, polyvinyl alcohol, polycaprolactone, polyurethanes and poly(N-isopropylacrylamide)) have been proven to exhibit suitable biodegradable and mechanical properties. Despite the fact that they show the required biocompatible behaviour, most synthetic polymers exhibit poor cell attachment capability. These synthetic polymers are mostly hydrophobic and lack cell recognition sites, limiting their application. Therefore, biofunctionalization of these biomaterials to enhance cell attachment and cell material interaction is being widely investigated. There are numerous approaches for functionalizing a material, which can be classified as mechanical, physical, chemical and biological. In this review, recent studies reported in the literature to functionalize scaffolds in the context of CTE, are discussed. Surface, morphological, chemical and biological modifications are introduced and the results of novel promising strategies and techniques are discussed.
© 2015 The Author(s) Published by the Royal Society. All rights reserved.
The extracellular matrix is a structural support network made up of
diverse proteins, sugars and other components. It influences a wide number of cellular
processes including migration, wound healing and differentiation, all of which is of
particular interest to researchers in the field of tissue engineering. Understanding the
composition and structure of the extracellular matrix will aid in exploring the ways the
extracellular matrix can be utilised in tissue engineering applications especially as a
scaffold. This review summarises the current knowledge of the composition, structure and
functions of the extracellular matrix and introduces the effect of ageing on
extracellular matrix remodelling and its contribution to cellular functions.
Additionally, the current analytical technologies to study the extracellular matrix and
extracellular matrix–related cellular processes are also reviewed.
Purpose:
This is the first study to report the clinical outcomes of photofunctionalized dental implants.
Materials and methods:
This retrospective study analyzed 95 consecutive patients who received 222 untreated implants and 70 patients who received 168 photofunctionalized implants over a follow-up period of 2.5 years. Photofunctionalization was performed by treating implants with UV light for 15 minutes using a photo device immediately before placement. The generation of superhydrophilicity and hemophilicity along with a substantial reduction in atomic percentage of surface carbon was confirmed after photofunctionalization. In both groups, 90% of the implants were placed in complex cases requiring staged or simultaneous site-development surgery. The implant stability was measured at implant placement and loading using the implant stability quotient (ISQ) values; then, the rate of implant stability development was evaluated by calculating the ISQ increase per month.
Results:
The healing time before functional loading was 3.2 months in photofunctionalized implants and 6.5 months in untreated implants. The success rate was 97.6% and 96.3% for photofunctionalized and untreated implants, respectively. The ISQ increase per month for photofunctionalized implants ranged from 2.0 to 8.7 depending on the ISQ at placement, and it was considerably higher than that of untreated implants reported in the literature ranging from -1.8 to 2.8. Photofunctionalization resulted in a more frequent use of implants of 10 mm or shorter length and an overall decrease in implant diameter.
Conclusions:
Within the limits of this retrospective study, despite the more frequent use of shorter and smaller-diameter implants, the use of photofunctionalization allowed for a faster loading protocol without compromising the success rate. The outcome was associated with an increased rate of implant stability development. The results suggest that photofunctionalization may provide a novel and practical avenue to further advance implant therapy.
The field of biomaterials has become a vital area, as these materials can enhance the quality and longevity of human life and the science and technology associated with this field has now led to multi-million dollar business. The paper focuses its attention mainly on titanium-based alloys, even though there exists biomaterials made up of ceramics, polymers and composite materials. The paper discusses the biomechanical compatibility of many metallic materials and it brings out the overall superiority of Ti based alloys, even though it is costlier. As it is well known that a good biomaterial should possess the fundamental properties such as better mechanical and biological compatibility and enhanced wear and corrosion resistance in biological environment, the paper discusses the influence of alloy chemistry, thermomechanical processing and surface condition on these properties. In addition, this paper also discusses in detail the various surface modification techniques to achieve superior biocompatibility, higher wear and corrosion resistance. Overall, an attempt has been made to bring out the current scenario of Ti based materials for biomedical applications.
Collagen fiber structure and organization have been found to vary in different tendon types. Differences have been reported in the FT-IR spectra of the amide I band of collagen-containing structures. In the present study, the FT-IR spectral characteristics of the amide I band of the bovine flexor tendon and the extended rat tail tendon were compared by using the diamond attenuated total reflectance technique. The objective was to associate FT-IR spectral characteristics in tendons with their different collagen fiber supraorganization and biomechanical properties. Nylon 6 and poly-L-lysine were used as polyamide models. Each of these materials was found to exhibit molecular order and crystallinity, as revealed by their birefringence. The following FT-IR parameters were evaluated: amide I band profile, absorption peaks and areas, and the 1655 cm⁻¹/1690 cm⁻¹ absorbance ratio. The amide I area and the 1655 cm⁻¹/1690 cm⁻¹ absorbance ratio were significantly higher for the bovine flexor tendon, indicating that its collagen fibers are richer in pyridinoline-type cross-linking, proline and/or hydroxyproline and H-bonding, and that these fibers are more packed and supraorganizationally ordered than those in the rat tail tendon. This conclusion is additionally supported by differences in collagen solubility and biochemical/biomechanical properties of the tendons.
This work is investigating the chemical grafting on Ti surface of a polymer/calcium phosphate coating of improved adhesion for enhanced bioactivity. For this purpose, a whole new methodology was developed based on covalently attaching a hyperbranched poly(ethylene imine) layer on Ti surface able to promote calcium phosphate formation in a next deposition stage. This was achieved through an intermediate surface silanization step. The research included optimization both of the reaction conditions for covalently grafting the intermediate organosilicon and the subsequent hyperbranched poly(ethylene imine) layers, as well as of the conditions for the mechanical and chemical pretreatment of Ti surface before coating. The reaction steps were monitored employing FTIR and XPS analyses, whereas the surface morphology and structure of the successive coating layers were studied by SEM combined with EDS. The analysis confirmed the successful grafting of the hybrid layer which demonstrated very good ability for hydroxyapatite growth in simulated body fluid.
Wettability at the surface of an implant material plays a key role in its success as it modulates the protein adsorption and thereby influences cell attachment and tissue integration at the interface. Hence, surface engineering of implantable materials to enhance wettability to physiological fluid under in vivo conditions is an area of active research. In light of this, in the present work, laser-based optical interference and direct melting techniques were used to develop synthetic microtextures on Ti-6Al-4V alloys, and their effects on wettability were studied systematically. Improved wettability to simulated body fluid and distilled water was observed for Ca-P coatings obtained by direct melting technique. This superior wettability was attributed to both the appropriate surface chemistry and the three-dimensional surface features obtained using this technique. To assert a better control on surface texture and wettability, a three-dimensional thermal model based on COMSOL's multiphysics was employed to predict the features obtained by laser melting technique. The effect of physical texture and wetting on biocompatibility of laser-processed Ca-P coatings was evaluated in the preliminary efforts on culturing of mouse MC3T3-E1 osteoblast cells.
Fourier transform infrared (FTIR) spectroscopy is an established tool for the structural characterization of proteins. However, many potential pitfalls exist for the unwary investigator. In this review we critically assess the application of FTIR spectroscopy to the determination of protein structure by (1) outlining the principles underlying protein secondary structure determination by FTIR spectroscopy, (2) highlighting the situations in which FTIR spectroscopy should be considered the technique of choice, (3) discussing the manner in which experiments should be conducted to derive as much physiologically relevant information as possible, and (4) outlining current methods for the determination of secondary structure from infrared spectra of proteins.
The biocompatibility of commercially pure titanium and its alloys is closely related to their surface properties, with both the composition of the protecting oxide film and the surface topography playing an important role. Surfaces of commercially pure titanium and of the two alloys Ti-6Al-7Nb and Ti-6Al-4V (wt %) have been investigated following three different pretreatments: polishing, nitric acid passivation and pickling in nitric acid-hydrogen fluoride. Nitric acid treatment is found to substantially reduce the concentration of surface contaminants present after polishing. The natural 4-6 nm thick oxide layer on commercially pure titanium is composed of titanium oxide in different oxidation states (TiO2, Ti2O3 and TiO), while for the alloys, aluminium and niobium or vanadium are additionally present in oxidized form (Al2O3, Nb2O5 or V-oxides). The concentrations of the alloying elements at the surface are shown to be strongly dependent on the pretreatment process. While pickling increases the surface roughness of both commercially pure titanium and the alloys, different mechanisms appear to be involved. In the case of commercially pure titanium, the dissolution rate depends on grain orientation, whereas in the case of the two alloys, selective alpha-phase dissolution and enrichment of the beta-phase appears to occur.
• Polished titanium discs were alkali treated to increase -OH groups on the surface.
• APTES was attached to alkali treated grade V titanium alloy surface via single bondOH groups.
• Free single bondNH2 groups of APTES are available for bio-conjugation with various biomolecules.
• Unique way to modify the titanium grade V alloy surface for biomedical applications
Different materials have distinct surface and bulk characteristics; each of them potentially useful for the treatment of a particular wound or disease. By reviewing those materials that have reached a clinical stage the reader will have a broad panorama of the possibilities a particular material can offer, regarding its ability to support fast tissue regeneration. This review covers the most recent advances made towards the development of biomaterials aimed to support regenerative processes. Indeed, we highlight key examples, from basic research to clinical trials, of biomaterials for a specific biomedical application. In this context, the focus is made on collagen, chitosan and silica which are key representatives of a protein, a polysaccharide and an inorganic material usually employed as biomaterials. Particularly, this review article presents an overview of their potential therapeutics in the treatment of disorders within the oral mucosa and tooth supporting tissues. Finally, the importance of in vivo and in vitro studies, clinical evidence studies, systematic reviews and meta-analyses as an adequate guidance for biomaterial design and development is highlighted.
Titanium alloys are prominent as dental and orthopedic materials because of their high strength-to-weight ratio, lower elastic modulus, excellent corrosion resistance and apparent biocompatibility. Based on microstructures that can be produced by alloying, titanium alloys are grouped as alpha, alpha-beta and beta alloys. Alpha titanium and alpha-beta alloys have been used for dental and orthopedic purposes. Beta titanium alloys are being considered as candidate materials for implant applications because of their ease of formability, increased strength and lower elastic modulus, in spite of increased cost. Studies show the presence of the omega phase in the beta alloy, Ti-15Mo-2.8Nb, in the unaged condition. Comparison of corrosion behavior of this alloy with the alloy Ti-6Al-4V shows the two alloys have comparable corrosion resistance in simulated physiological solution. A review and data are presented along with a discussion of the influence of composition, heat treatment and microstructure on mechanical properties and corrosion behavior of titanium alloys, in general, and of beta alloys, in particular.
Titanium and its alloys have excellent properties and are promising biomaterial in medical engineering field. A bioactive surface on a Ti substrate is a prerequisite for great performance and long service life of implants. Based on the mechanism for inducing cell/tissue responses, three kinds of methods, namely morphological, physicochemical and biochemical methods, are reviewed in this paper. Hybrid methods that integrate individual methods or have additional functions are also discussed.
An anti-microbial and bioactive coating could not only reduce the probability of infection related to titanium implants but also support the growth of surrounding osteogenic cells. Our previous study has showed that hydroxypropyltrimethyl ammonium chloride chitosan (HACC) with a DS (degrees of substitution) of 18% had improved solubility and significantly higher antibacterial activities against three bacteria which were usually associated with infections in orthopaedics. In the current study, HACC with a DS of 18% coating was bonded to titanium surface by a three-step process. The titanium surface after each individual reaction step was analyzed by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection (ATR) of Fourier-transformed infrared (FT-IR) spectroscopy. The XPS results demonstrated that there were great changes in the atomic ratios of C/Ti, O/Ti, and N/Ti after each reaction step. The XPS high resolution and corresponding devolution spectra of carbon, oxygen, nitrogen, and titanium were also in good coordination with the anticipated reaction steps. Additionally, the absorption bands around 3365cm−1 (–OH vibration), 1664cm−1 (Amide I), 1165cm−1 (νas, C–O–C bridge), and the broad absorption bands between 958cm−1 and 1155cm−1 (skeletal vibrations involving the C–O stretching of saccharide structure of HACC) verified that HACC was successfully attached to titanium surface.
This article reviews some of the recent advances on FTIR spectroscopy in areas related to natural tissues and cell biology. It is the second review publication resulting from a detailed study on the applications of spectroscopic methods in biological studies and summarizes some of the most widely used peak frequencies and their assignments. The aim of these studies is to prepare a database of molecular fingerprints, which will help researchers in defining the chemical structure of the biological tissues introducing most of the important peaks present in the natural tissues. In spite of applying different methods, there seems to be a considerable similarity in defining the peaks of identical areas of the FTIR spectra. As a result, it is believed that preparing a unique collection of the frequencies encountered in FTIR spectroscopic studies can lead to significant improvements both in the quantity and quality of research and their outcomes. This article is the first review of its kind that provides a precise database on the most important FTIR characteristic peak frequencies for researchers aiming to analyze natural tissues by FTIR spectroscopy and will be of considerable assistance to those who are focusing on the analysis of cancerous tissues by FTIR spectroscopy.
Surface modification of dental implants with biomolecules is of particularly interest recently. To mimic the structure and function of native extracellular matrix (ECM), a derivative of hyaluronic acid (HA), HA-GRGDSP, was synthesized, Arg-Gly-Asp (RGD)-containing collagen (Col)/HA multilayer polyelectrolyte films (MPFs) coating was fabricated on titanium (Ti) through alternate deposition of Col and HA-GRGDSP with 4.5 assembly cycles; moreover, bioactive molecule, basic fibroblast growth factor (bFGF), was also incorporated into such coating. This coating was then carefully characterized using scanning electronic microscope (SEM) and scanning force microscopy (SFM); bFGF release from the coating was also evaluated. (Col + bFGF)/HA-RGD coating was successfully deposited on Ti surface, and about 300 pg of bFGF could be slowly released from this coating for a week. This coating significantly promoted the initial cell attachment of human gingival fibroblasts (HGFs) compared with other groups (p < 0.05), and HGFs adhered and spread better on this coating than other groups (p < 0.05). Regarding cell proliferation and differentiation of HGFs, they were greatly stimulated when cultured on this coating (p < 0.05). These results indicated that surface modification of Ti using biomolecules might improve the sealing between the neck section of a dental implant and the soft tissue. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
In this study, the titanium plates, which were modified by NaOH alkali solution, were associated with 3-Aminopropyltriethoxysilane (APTES) films using self-assembled monolayers (SAMs). The surfaces of titanium before and after modification were characterized by scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and attenuated total refraction–Fourier transform infrared spectroscopy (ATR–FTIR). After bonding the APTES films on the modification titanium, the new peaks located around 1095 cm−1 attributes to siloxane groups indicating that silane agent had been grafted onto the surface of the modification titanium substrate by SAMs. Following the deposition of APTES films on titanium, significant change were seen in the amounts of oxygen, silicon and carbon present on the titanium surface, which were consistent with the anticipated reaction steps.
Titanium and titanium alloys are widely used in biomedical devices and components, especially as hard tissue replacements as well as in cardiac and cardiovascular applications, because of their desirable properties, such as relatively low modulus, good fatigue strength, formability, machinability, corrosion resistance, and biocompatibility. However, titanium and its alloys cannot meet all of the clinical requirements. Therefore, in order to improve the biological, chemical, and mechanical properties, surface modification is often performed. This article reviews the various surface modification technologies pertaining to titanium and titanium alloys including mechanical treatment, thermal spraying, sol–gel, chemical and electrochemical treatment, and ion implantation from the perspective of biomedical engineering. Recent work has shown that the wear resistance, corrosion resistance, and biological properties of titanium and titanium alloys can be improved selectively using the appropriate surface treatment techniques while the desirable bulk attributes of the materials are retained. The proper surface treatment expands the use of titanium and titanium alloys in the biomedical fields. Some of the recent applications are also discussed in this paper. # 2004 Elsevier B.V. All rights reserved.
A three-step reaction procedure was applied to introduce RGD-containing peptides on the titanium surface. Water-vapor-plasma-pretreated titanium surfaces were first silanized with (3-aminopropyl)-triethoxysilane, resulting in a multilayer film of poly(3-aminopropyl)siloxane. In a second reaction step, the free primary amino groups were linked to one of the three hetero-cross-linkers: N-succinimidyl-6-maleimidylhexanoate, N-succinimidyl-3-maleimidylpropionate, and N-succinimidyl trans-4-(maleimidylmethyl)cyclohexane-1-carboxylate. Onto the resulting terminal-maleimide surface, two model, cell-adhesive peptides, H-Gly-Arg-Gly-Asp-Ser-Pro-Cys-OH and H-Arg-Gly-Asp-Cys-OH were immobilized through covalent addition of the cysteine thiol (-SH) group. X-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, and radiolabeling techniques were applied to characterize the surfaces. From independent quantitative analysis, an approximate coverage of 0.2 similar to 0.4 peptides/nm(2) was calculated.
Cell attachment and spreading to titanium-based alloy surfaces is a major parameter in implant technology. In this paper, substratum surface hydrophobicity, surface free energy, interfacial free energy and surface roughness were investigated to ascertain which of these parameters is predominant in human fibroblast spreading. Two methods for contact angle measurement were compared: the sessile drop method and the captive bubble two-probe method. The relationship between surface roughness and the sessile drop contact angles of various engineered titanium surfaces such as commercial pure titanium (cp-Ti), titanium–aluminium–vanadium alloy (Ti–6Al–4V), and titanium–nickel (NiTi), was shown. Surface free energy (SFE) calculations were performed from contact angles obtained on smooth samples based on the same alloys in order to eliminate the roughness effect. SFE of the surfaces have been calculated using the Owens–Wendt (OW) and Van Oss (VO) approaches with the sessile drop method. The OW calculations are used to obtain the dispersive (γd) and polar (γp) component of SFE, and the VO approach allows to reach the apolar (γLW) and the polar acid–base component (γab) of the surface. From captive bubble contact angle experiments (air or octane bubble under water), the interfacial free energy of the different surfaces in water was obtained. A relationship between cell spreading and the polar component of SFE was found. Interfacial free energy values were low for all the investigated surfaces indicating good biocompatibility for such alloys.
The electrochemical behavior of Ti–6Al–4V and Ti–6Al–7Nb alloys, commonly used implant materials, particularly for orthopaedic and osteosynthesis applications, was investigated together with that of Ti–13Nb–13Zr alloy in Hank's solution at 37 °C. The aim of present study was to evaluate their corrosion resistance in an artificial physiological solution. This evaluation was carried out through the analysis of the corrosion potential variation with time, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS) tests. Very low current densities were obtained (order of nA/cm2) from the polarization curves, indicating a typical passive behavior for all investigated alloys. The EIS results exhibited capacitive behavior (high corrosion resistance) with phase angles close to −90° and high impedance values (order of 106 Ω cm2) at low and medium frequencies, which are indicative of the formation of a highly stable film on these alloys in the test solution. The obtained EIS spectra indicated two relaxation time constants and their interpretation in terms of an “equivalent circuit” with the circuit elements representing the electrochemical properties of a two-layer oxide, composed of a porous outer layer and a dense inner layer, was in good agreement. The electrochemical impedance spectroscopy (EIS) technique, therefore, was able to provide reliable data for determination of the passive film structure.
Surfaces play a vial role in biology and medicine with most biological reactions occurring at surfaces and interfaces. The foundations, evolution, and impact of biomedical surface science are discussed. In the 19th century, the first observations were made that surfaces control biological reactions. The advancements in surface science instrumentation that have occurred in the past quarter of a century have significantly increased our ability to characterize the surface composition and molecular structure of biomaterials. Similar advancements have occurred in material science and molecular biology. The combination of these advances have allowed the development of the biological model for surface science, where the ultimate goal is to gain a detailed understanding of how the surface properties of a material control the biological reactivity of a cell interacting with that surface. Numerous examples show that the surface properties of a material are directly related to in vitro biological performance such as protein adsorption and cell growth. The challenge is to fully develop the biological model for surface science in the highly complex and interactive in vivo biological environment. Examples of state-of-the-art biomedical surface science studies on surface chemical state imaging, molecular recognition surfaces, adsorbed protein films, and hydrated surfaces are presented. Future directions and opportunities for surface scientists working in biomedical research include exploiting biological knowledge, biomimetics, precision immobilization, self-assembly, nanofabrication, smart surfaces, and control of non-specific reactions.
The structure of γ-aminopropyltriethoxysilane (γ-APS) films deposited on mechanically polished iron mirrors from aqueous solutions has been investigated using reflection-absorption infrared spectroscopy. Films formed at the natural pH of 1% aqueous solutions of γ-APS (∼10.5) were about 120 Å in thickness and were composed of highly hydrolyzed oligomers characterized by infrared bands near 1550 and 1480 cm−1. These bands were assigned to NH2 deformation modes in amino groups that were very strongly hydrogen bonded with silanol groups to form cyclic structures. Films formed at pH = 12 were characterized by infrared bands near 1580 and 1488 cm−1 that were assigned to deformation modes of NH+3 groups obtained by essentially complete proton transfer from silanol groups to amino groups. In all cases the as-formed films were stable in a dry environment but exposure to atmospheric humidity disrupted the strong hydrogen bonding, enabling the oligomers to condense to form polysiloxanes.
In the daily clinical routine, numerous synthetic medical devices are implanted in the human body, either temporarily or permanently. The synthetic material most often implanted is polydimethylsiloxane (silicone). Numerous studies have demonstrated that silicone is encompassed in a connective tissue capsule by the body, preventing integration into the surrounding tissue. This can result in complications. The aim of our study was to develop a simple procedure to functionalize the silicone surface, thereby positively affecting the material's biocompatibility. By combining a silanization with the use of ester activation, a reactive amino group is generated, which can bind any free carboxyl group. Directional crosslinking of a near-infrared-conjugated fluorophore antibody to the activated silicone surface could be demonstrated on a dose-dependent basis. The redox reaction at a silicone surface coated with an HRP-conjugated antibody caused by the addition of NBT/BCIP could be shown. Covering the silicone discs with an anti-FAS-antibody coating followed by a coincubation with FAS-sensitive T-cells allowed highly significant detection of caspase-3. In summary, our crosslinking procedure enables the stable binding of proteins without the loss of biological function. Through this process, silicones could be endowed with new functions which could improve their biocompatibility.
To give an overview of aspects of silane coupling agents and surface conditioning in dentistry.
Currently, silane coupling agents are used as adhesion promoters. Silanes are effective in enhancing adhesion between resin composite and silica-based ceramics. They do not bond effectively to non-silica based dental restorative materials. Surface conditioning of non-silica based ceramics with silica coating improves the bonding. This current overview will focus on the silane coupling agents: their properties, limitations in adhesion promotion and the clinical problems with the use of silanes. It will also focus on the current surface conditioning methods as well as new surface conditioning techniques to enhance the bonding through conventional silanization approaches.
Several surface conditioning methods are being used clinically to enhance the adhesion of resin composites to non-silica based restorative materials. Other approaches are under investigation. The clinical problem of using silanes in adhesion promotion is the bond degradation over time in oral environment.
The current silane coupling agents are not ideal. The current silane coupling agents can fulfill the minimum requirements in clinical practice to enhance the bonding of resin composite to dental restorative materials. Developments of novel surface conditioning methods and silane coupling agents are required to address the bond durability problem.
The understanding of the mechanisms involved in the interaction of biological systems with inorganic materials is of interest in both fundamental and applied disciplines. The adsorption of proteins modulates the formation of biofilms onto surfaces, a process important in infections associated to medical implants, in dental caries, in environmental technologies. The interaction with biomacromolecules is crucial to determine the beneficial/adverse response of cells to foreign inorganic materials as implants, engineered or accidentally produced inorganic nanoparticles. A detailed knowledge of the surface/biological fluids interface processes is needed for the design of new biocompatible materials. Researchers involved in the different disciplines face up with similar difficulties in describing and predicting phenomena occurring at the interface between solid phases and biological fluids. This review represents an attempt to integrate the knowledge from different research areas by focussing on the search for determinants driving the interaction of inorganic surfaces with biological matter.
In the current study, we have altered the surface oxide properties of a Ti6Al4V alloy using heat treatment or radiofrequency glow discharge (RFGD) in order to evaluate the relationship between the physico-chemical and biological properties of the alloy's surface oxide. The effects of surface pretreatments on the attachment of cells from two osteogenic cell lines (MG63 and MC3T3) and a mesenchymal stem cell line (C3H10T1/2) to fibronectin adsorbed to the alloy were measured. Both heat and RFGD pretreatments produced a several-fold increase in the number of cells that attached to fibronectin adsorbed to the alloy at a range of coating concentrations (0.001-10nM FN) for each cell line tested. An antibody (HFN7.1) directed against the central integrin binding domain of fibronectin produced a 65-70% inhibition of cell attachment to fibronectin-coated disks, indicating that cell attachment to the metal discs was dependent on fibronectin binding to cell integrin receptors. Both treatments also accelerated the cell spreading response manifested by extensive flattening and an increase in mean cellular area. The treatment-induced increases in the cell attachment activity of adsorbed fibronectin were correlated with previously demonstrated increases in Ti6Al4V oxide negative net surface charge at physiological pH produced by both heat and RFGD pretreatments. Since neither treatment increased the adsorption mass of fibronectin, these findings suggest that negatively charged surface oxide functional groups in Ti6Al4V can modulate fibronectin's integrin receptor activity by altering the adsorbed protein's conformation. Our results further suggest that negatively charged functional groups in the surface oxide can play a prominent role in the osseointegration of metallic implant materials.
Two human pathogenic bacteria, Staphylococcus aureus CIP 68.5 and Pseudomonas aeruginosa ATCC 9025, were adsorbed onto surfaces containing Ti thin films of varying thickness to determine the extent to which nanoscale surface roughness influences the extent of bacterial attachment. A magnetron sputter thin film system was used to deposit titanium films with thicknesses of 3, 12, and 150 nm on glass substrata with corresponding surface roughness parameters of R(q) 1.6, 1.2, and 0.7 nm (on a 4 microm x 4 microm scanning area). The chemical composition, wettability, and surface architecture of titanium thin films were characterized using X-ray photoelectron spectroscopy, contact angle measurements, atomic force microscopy, three-dimensional interactive visualization, and statistical approximation of the topographic profiles. Investigation of the dynamic evolution of the Ti thin film topographic parameters indicated that three commonly used parameters, R(a), R(q), and R(max), were insufficient to effectively characterize the nanoscale rough/smooth surfaces. Two additional parameters, R(skw) and R(kur), which describe the statistical distributions of roughness character, were found to be useful for evaluating the surface architecture. Analysis of bacterial retention profiles indicated that bacteria responded differently to the surfaces on a scale of less than 1 nm change in the R(a) and R(q) Ti thin film surface roughness parameters by (i) an increased number of retained cells by a factor of 2-3, and (ii) an elevated level of secretion of extracellular polymeric substances.
A layer of sodium titanate hydrogel on titanium alloy (Ti6Al4V) induces apatite formation in simulated body fluid (SBF). This paper seeks to determine the parameters of alkaline-treated and subsequent heat treatment which lead to the most rapid formation of apatite. Specimens were soaked in 3, 5, 10 or 15 M solutions of NaOH at temperatures of 60 or 80 °C for 1, 3 or 7 days. It was found that the optimum treatment for the Ti6Al4V alloy was a 3-day soak in 5 M NaOH solution at 80 °C. Specimens treated under these optimum conditions were subsequently heat-treated at 500, 600, and 700 °C for 1 h so as to consolidate the sodium titanate hydrogel layer and improve its bonding to the substrate. Treatment at 600 °C resulted in the best bonding and the optimum rate of apatite formation. On soaking in simulated body fluid (SBF), apatite formed within 3 days, as compared to the 7-day formation, which was the best rate previously reported. The acceleration in the rate of apatite formation is significant, as it should allow for earlier load bearing of prostheses following implantation.
This study examined the possible changes in the bioactivity of titanium surfaces during their aging and investigated the effect of ultraviolet (UV) light treatment during the age-related change of titanium bioactivity. Rat bone marrow-derived osteoblastic cells were cultured on new titanium disks (immediately after either acid-etching, machining, or sandblasting), 4-week-old disks (stored after processing for 4 weeks in dark ambient conditions), and 4-week-old disks treated with UVA (peak wavelength of 365 nm) or UVC (peak wavelength of 250 nm). During incubation for 24 h, only 50% of the cells were attached to the 4-week-old surfaces as compared to the new surface. UVC treatment of the aged surface increased its cell attachment capacity to a level 50% higher than the new surfaces, whereas UVA treatment had no effect. Proliferation, alkaline phosphatase activity, and mineralization of cells were substantially lower on the 4-week-old surfaces than on the new surfaces, while they were higher on the UVC-treated 4-week-old surfaces as compared to the new surfaces. The age-related impaired bioactivity was found on all titanium topographies as well as on a chromium-cobalt alloy, and was associated with an increased percentage of surface carbon. Although both UVA and UVC treatment converted the 4-week-old titanium surfaces from hydrophobic to superhydrophilic, only UVC treatment effectively reduced the surface carbon to a level equivalent to the new surface. Thus, this study uncovered a time-dependent biological degradation of titanium and chromium-cobalt alloy, and its restoration enabled by UVC phototreatment, which surmounts the innate bioactivity of new surfaces, which is more closely linked to hydrocarbon removal than the induced superhydrophilicity.
Titanium implants are used as a reconstructive anchor in orthopedic and dental diseases and problems. Recently, ultraviolet (UV) light-induced photocatalytic activity of titanium has earned considerable and broad interest in environmental and clean-energy sciences. This study determines whether UV treatment of titanium enhances its osteoconductive capacity. Machined and acid-etched titanium samples were treated with UV for various time periods up to 48h. For both surfaces, UV treatment increased the rates of attachment, spread, proliferation and differentiation of rat bone marrow-derived osteoblasts, as well as the capacity of protein adsorption, by up to threefold. In vivo histomorphometry in the rat model revealed that new bone formation occurred extensively on UV-treated implants with virtually no intervention by soft tissue, maximizing bone-implant contact up to nearly 100% at week 4 of healing. An implant biomechanical test revealed that UV treatment accelerated the establishment of implant fixation 4 times. The rates of protein adsorption and cell attachment strongly correlated with the UV dose-responsive atomic percentage of carbon on TiO2, but not with the hydrophilic status. The data indicated that UV light pretreatment of titanium substantially enhances its osteoconductive capacity, in association with UV-catalytic progressive removal of hydrocarbons from the TiO2 surface, suggesting a photofunctionalization of titanium enabling more rapid and complete establishment of bone-titanium integration.
Amino-functionalized organic films were prepared by self-assembling 3-aminopropyltriethoxysilane (APTES) on silicon wafers in either anhydrous toluene or phosphate-buffered saline (PBS) for varied deposition times. Fourier transform infrared spectroscopy (FTIR) and ellipsometry have shown that the structure and thickness of APTES films are governed by the deposition time and reaction solution. Deposition from an anhydrous toluene solution produces APTES films ranging from 10 to 144 A in thickness, depending on the reaction time. FTIR spectra indicate that film growth initially proceeds by adsorption of APTES to the silicon surface followed by siloxane condensation, and after an extended period of time APTES molecules accumulate on the underlying APTES film by either covalent or noncovalent interactions. In contrast, spectroscopically indistinguishable APTES films in thickness ranging from 8 to 13 A were formed when deposition was conducted in aqueous solutions. Measured water contact angles indicate that APTES films deposited in aqueous solutions are more hydrophilic compared to those prepared in toluene solutions. Fluorescence measurements revealed that APTES films prepared in toluene solutions contain more reactive surface amino groups by ca. 3 to 10 times than those prepared in aqueous solutions for the identical reaction time.
The infrared amide I band of collagens (rat and cod skin) and related compounds (polyproline, polyglycine, and polytripeptides) was studied. Assignment of amide I-band components for polyproline II and polytripeptides (Gly-Pro-Pro)n and (Gly-Pro-Gly)n in the solid state and water solution was made. Three amide I components observed in the polypeptide spectra were attributed to three different peptide CO groups in each triplet. On the basis of this assignment, the interpretation of the amide I multicomponent structure in collagen and isomorphous oligo- and polypeptides was attempted. The ordering of intra- and intermolecular hydrogen bonds involving peptide CO groups in collagen and related compounds was discussed.
The goal of placement of endosseous dental implants is to achieve osseointegration or biointegration of the bone with the implant. A wide variety of materials has been used for these implants, but only a few promote osseointegration and biointegration. Titanium and titanium alloy (Ti6A14V) have been the most widely used of these materials. The surface oxide of titanium appears to be central to the ability of this material to osseointegrate. The oxide limits dissolution of elements and promotes the deposition of biological molecules which allow bone to exist as close as 30 A to the surface of the implant. The details of the ultrastructure of the gap between the implant and bone remain undefined, and the consequences of elements which are released on the interface over time are not known. These areas of investigation are particularly important in defining the differences between commercially pure titanium implants and those made of titanium, aluminium and vanadium. The epithelial interface between the gingiva and titanium appears to contain many of the structural characteristics of the native tooth-gingiva interface, but details are still vague. The connective tissue interface with the titanium appears to be one of tightly fitting tissues rather than adhesion. Ceramic coatings appear to improve the ingrowth of bone and promote chemical integration of the implant with the bone. The characteristics of these coatings are complex and affect the bony response, but the mechanisms remain obscure. The degradation of the coatings is an issue of particular controversy. Progress in dental implantology is likely to continue as the interface between the material and bone is more clearly understood, and biological molecules and artificial tissues are developed.
The formation of a biological seal around the transmucosal portion of dental implants may be crucial for the long-term success of these therapies. Data to date suggest that the gingival epithelium attaches to dental implants through the formation of hemidesmosomes. Biochemical and genetic data indicate that the laminin isoform, laminin-5, a component of basement membranes, plays a crucial role in the assembly and maintenance of hemidesmosomes. We report the use of soluble laminin-5 as a biological coating of titanium-alloy to promote cell attachment of the gingival epithelial cell line, IHGK. Monoclonal antibodies reactive with laminin-5 depleted the coating solution of all cell attachment activity and blocked cell attachment to laminin-5-coated disks. Immunodepletion with antibodies to fibronectin had no effect. Finally, we demonstrate that IHGK cells assembled hemidesmosomes within 24 h of attachment to laminin-5-coated titanium alloy but not to the titanium alloy alone. These results suggest that soluble laminin-5 may have clinical applications as a dental implant coating to promote the formation of a biological seal.
The gas-phase reaction of (3-aminopropyl)dimethylethoxysilane (APDMES) with silica with and without amine catalysts has been studied using infrared spectroscopy. Evidence is provided that shows that the aminosilane initially adsorbs via hydrogen bonding of both ethoxy and aminopropyl moieties of the silane with the surface hydroxyl groups. As the reaction proceeds, the number of silane molecules attached to the surface via a Si-O-Si linkage increases primarily at the expense of the number of H-bonded ethoxy groups. The conversion is due to a catalytic process involving the aminopropyl end of gaseous APDMES molecules. On the other hand, the H-bonded aminopropyl groups are less reactive and only a small portion of these groups participates in Si-O-Si bond formation. At the end of the reaction there remain about 50% of the adsorbed APDMES attached by the H-bonded aminopropyl group. Attempts to block the adsorption of the aminopropyl end through the use of the more strongly H-bonded triethylamine proved unsuccessful. The use of preadsorbed triethylamine or 1 : 10 mixtures of triethylamine/APDMES accelerates the reaction but in the end leads to the same final distribution of products on the surface. Copyright 2000 Academic Press.
Articular cartilage, a connective tissue that provides resistance to compressive forces during joint movements, has not been examined in detail by conventional Fourier transform infrared (FTIR) spectroscopy, microspectroscopy (FTIRM), or imaging (FTIRI). The current study reports FTIRM and FTIRI analyses of normal bovine cartilage and identifies the specific molecular components of cartilage that contribute to its IR spectrum. FTIRM data acquired through the superficial, middle, and deep zones of thin sections of bovine articular cartilage showed a variation in intensities of the absorbance bands that arise from the primary nonaqueous components of cartilage, collagen, and proteoglycan (primarily aggrecan) and thus reflected the differences in quantity of these specific components. The spectra of mixtures of model compounds, which had varying proportions of type II collagen and aggrecan, were analyzed to identify spectral markers that could be used to quantitatively analyze these components in cartilage. Collagen and aggrecan were then imaged by FTIRI based on markers found in the model compounds. Polarization experiments were also performed to determine the spatial distribution of the collagen orientation in the different zones of cartilage. This study provides a framework in which complex pathological changes in this heterogeneous tissue can be assessed by IR microscopic imaging.
An adequate supply of saliva is critical to the preservation and maintenance of oral tissue. Clinicians often do not value the many benefits of saliva until quantities are decreased. Much is written on the subject of salivary hypofunction, but little attention is paid to normal salivary flow and function. This article is a brief, up-to-date overview of the literature on the basics of normal salivary composition, flow, and function. A review of the literature was conducted using MEDLINE and Healthstar (1944 through 1999); articles were selected for inclusion on the basis of relevance and significance to the clinician.
The attachment of cells to titanium surfaces is an important phenomenon in the area of clinical implant dentistry. A major consideration in designing implants has been to produce surfaces that promote desirable responses in the cells and tissues. To achieve these requirements, the titanium implant surface can be modified in various ways. This research was designed to elucidate the relationship between surface roughness (Ra) and contact angle (theta) of various engineered titanium surfaces of commercially pure titanium, titanium-aluminum-vanadium alloy (Ti-6Al-4V), and titanium-nickel (TiNi) alloy. The contact angle was measured using distilled water, 1% sodium chloride solution, human neutrophils, and osteoblast-like cells. Surface oxide crystallography was identified by transmission electron diffraction. It was found that: (1) there were no significant differences in contact angles among the 4 media; (2) for commercially pure titanium, a combined treatment (hydrofluoric acid/nitric acid/water --> sodium hydroxide --> oxidation) showed the lowest theta (10.51 degrees in water), while the surface treated with sulfuric acid showed the highest value (72.99 degrees in water); (3) for all commercially pure titanium samples, when theta is greater than 45 degrees, the contact angle increases linearly with Ra (hydrophobic nature) and the surface is covered with rutile-type oxide only, while the contact angle decreases linearly with Ra when theta is less than 45 degrees (hydrophilic nature) and the surface is covered with a mixture of rutile and anatase oxides; and (4) a similar trend was found on Ti-6Al-4V and TiNi surfaces.
Collagens are the most abundant structural proteins found in the extracellular matrix of vertebrates. Knowledge of the mechanical behavior of collagen monomers is essential for understanding the mechanical properties of collagen fibrils that constitute the main architectural framework of skin, bone, cartilage, and other connective tissues. In this study, the flexibility of type I collagen monomer was studied by stretching type I collagen monomers directly. The force-extension relationship was measured and analyzed by fitting the data into a worm-like chain elasticity model. The persistence length of collagen I monomer was determined to be 14.5 nm and the contour length was 309 nm. The results confirm that type I collagen monomer is flexible rather than rigid, rod-like molecule. Such flexibility may possibly be a consequence of the micro-unfolding of discrete domains of single collagen molecule.
FT-IR analysis was performed for the hydroxyapatite (HAp)/collagen (COL) nanocomposite cross-linked by glutaraldehyde (GA). The amide bands I, II and III from COL matrix, and phosphate and carbonate bands from HAp were identified. The amide B band arising from C-H stretching mode showed a sensitive conformation by the degree of cross-linking. The amide I band showed a complicate conformational change by the degree of cross-linking. The characteristic amide I band at 1685 cm(-1), which is known as an aging parameter in the biological bone, did not show a monotonous tendency by the degree of cross-linking. The relative contents of the organics in the cross-linked HAp/COL nanocomposite were evaluated as an integration ratio between the amide I band at 1600-1700 cm(-1) and PO(4)(3-) band at 900-1200 cm(-1). The increase of the organics content by the cross-linking is enabled by the further organization of Ca(2+) ions of HAp crystals in HAp/COL nanocomposite. The complicate conformational behavior in the amide I, II and III bands seems to be affected by the cross-linking induced directional arrangement of HAp/COL nanocomposite fibrils.
To investigate the roles of composition and characteristics of titanium surface oxides in cellular behaviour of osteoblasts, the surface oxides of titanium were modified in composition and topography by anodic oxidation in two kinds of electrolytes, (a) 0.2 M H(3)PO(4), and (b) 0.03 M calcium glycerophosphate (Ca-GP) and 0.15 M calcium acetate (CA), respectively. Phosphorus (P: ca.10at%) or both calcium (Ca: 1-6at%) and phosphorus (P: 3-6at%) were incorporated into the anodized surfaces in the form of phosphate and calcium phosphate. Surface roughness was slightly decreased or enhanced (R(a) in the range of 0.1-0.5 microm) on the anodized surfaces. The geometry of the micro-pores in the anodized surfaces varied with diameters up to 0.5 microm in 0.2 M H(3)PO(4) and to 2 microm in 0.03 M Ca-GP and 0.15 M CA, depending on voltages and electrolyte. Contact angles of all the anodic oxides were in the range of 60-90 degrees. Cell culture experiments demonstrated absence of cytotoxicity and an increase of osteoblast adhesion and proliferation by the anodic oxides. Cells on the surfaces with micro-pores showed an irregular and polygonal growth and more lamellipodia, while osteoblasts on the titanium surface used as a control or on anodic oxides formed at low voltages showed many thick stress fibres and intense focal contacts. Alkaline phosphatase (ALP) activity of the cells did not show any correlation with surface characteristics of anodic oxides.
A direct comparison of surface loading, interface shear strength, and interface hydrolytic stability was made between a phosphonate and two siloxane monolayers formed on the native oxide surface of Ti-6Al-4V. Surface loading for the phosphonate was ca. four times greater (on a nanomole/area basis) than for the siloxanes; mechanical strengths per surface-bound molecule were comparable, but the hydrolytic stability (pH 7.5) of the siloxanes was poor. These results suggest that phosphonate monolayer interfaces are more desirable than comparable siloxane ones for applications where such interfaces contact even slightly alkaline water.
Roughness-induced hydrophobicity, well-known from natural plant surfaces and intensively studied toward superhydrophobic surfaces, has currently been identified on microstructured titanium implant surfaces. Studies indicate that microstructuring by sandblasting and acid etching (SLA) enhances the osteogenic properties of titanium. The undesired initial hydrophobicity, however, presumably decelerates primary interactions with the aqueous biosystem. To improve the initial wettability and to retain SLA microstructure, a novel surface modification was tested. This modification differs from SLA by its preparation after acid etching, which was done under protective gas conditions following liquid instead of dry storage. We hypothesized that this modification should have increased wettability due to the prevention of contaminations that occurs during air contact. The main outcome of dynamic wettability measurements was that the novel modification shows increased surface free energy (SFE) and increased hydrophilicity with initial water contact angles of 0 degrees compared to 139.9 degrees for SLA. This hydrophilization was kept even after any drying. Reduced hydrocarbon contaminations were identified to play a possible role in altered surface thermodynamics. Such surfaces aim to retain the hydrophilicity and natural high surface energy of the Ti dioxide surface until surgical implants' insertion and are compared in this in vitro study with structural surface variants of titanium to compare roughness and chemically induced wettability.
There has been limited published research assessing the range of oral temperature that the dental hard and soft tissues are exposed to. The temperatures that tooth structure and dental restorations encounter affect the performance of dental materials within the oral environment. This study therefore assessed the range of temperatures that a selected group could tolerate when drinking and also assessed the range of temperatures encountered in various intra-oral sites. These temperature fluctuations are for very brief periods of time but have a wide and varied range. Miniature dataloggers allowed for accurate measurements and recording of temperature from selected sites. The range of temperature recorded amongst the individuals tested shows the protection afforded to the dental hard tissues by the soft tissues of the oral cavity. The maximum and minimum mouth temperatures recorded show that hot fluids can raise the intra-oral temperature of the front teeth to around 70 degrees C and the consumption of iced drinks lowers the same teeth to around 0 degrees C. The range of temperature of hot fluids that can be tolerated by a selected group vary, but this does not seem to be the case for cold fluids. The thermistor beads mounted on the buccal surface of the lower front teeth and the palatal of the upper front teeth are exposed to the greatest temperature fluctuations during drinking fluids from a cup. The importance of these temperatures recorded in terms of dental materials testing and the role of material conductivity warrants further investigation.