Description

The aim of Bio-medical Materials and Engineering is to promote the welfare of humans and to help them keep healthy. This International Journal is an interdisciplinary journal that will publish original research papers, review articles and brief notes on materials and engineering for biological and medical systems. Articles in this peer-reviewed journal will cover a wide range of topics, including, but not limited to: Engineering as applied to improving diagnosis, therapy, and prevention of disease and injury, and better substitutes for damaged or disabled human organs, such as drug delivery, medical devices, systems and artificial organs; Studies of biomaterial interactions with the human body, bio-compatibility, interfacial and interaction problems; Biomechanical behaviour under biological and/or medical conditions, such as, fracture toughness, fatigue, creep, stress corrosion cracking, corrosion fatigue, plasticity, visco-elasticity, rheology, tribology and wear, and behaviour under impact, mechanics and devices for promotion of physical strength; Mechanical and biological properties of membrane biomaterials; Cellular and tissue engineering, physiological, biophysical, biochemical bioengineering aspects; Implant failure fields and degradation of implants. Biomimetics engineering and materials including system analysis as supporter for aged people and as rehabilitation; Bioengineering and materials technology as applied to the decontamination against environmental problems; Biosensors, bioreactors, bioprocess instrumentation and control system; Application to food engineering; Standardization problems on biomaterials and related products; Assessment of reliability and safety of biomedical materials and man-machine systems; Product liability of biomaterials and related products.

Publisher details

IOS Press

Publications in this journal

• Biocompatibility of metal injection molded versus wrought ASTM F562 (MP35N) and ASTM F1537 (CCM) cobalt alloys.

  Authors: Hao Chen, Alan Sago, Shari West, Jeff Farina, John Eckert, Mark Broadley

  Bio-medical materials and engineering. 21(1):1-7.

  We present a comparative analysis between biocompatibility test results of wrought and Metal Injection Molded (MIM) ASTM F562-02 UNS R30035 (MP35N) and F1537 UNS R31538 (CCM) alloy samples that haveWe present a comparative analysis between biocompatibility test results of wrought and Metal Injection Molded (MIM) ASTM F562-02 UNS R30035 (MP35N) and F1537 UNS R31538 (CCM) alloy samples that have undergone the same generic orthopedic implant's mechanical, chemical surface pre-treatment, and a designed pre-testing sample preparation method. Because the biocompatibility properties resulting from this new MIM cobalt alloy process are not well understood, we conducted tests to evaluate cytotoxicity (in vitro), hemolysis (in vitro), toxicity effects (in vivo), tissue irritation level (in vivo), and pyrogenicity count (in vitro) on such samples. We show that our developed MIM MP35N and CCM materials and treatment processes are biocompatible, and that both the MIM and wrought samples, although somewhat different in microstructure and surface, do not show significant differences in biocompatibility.

• Oral delivery of insulin using chitosan capsules cross-linked with phytic acid.

  Authors: Hyunah Lee, Chanmin Jeong, Kashif Ghafoor, Sungyeon Cho, Jiyong Park

  Bio-medical materials and engineering. 21(1):25-36.

  Phytic acid (PA) was used as a cross-linking agent for encapsulation of insulin in a chitosan matrix for oral delivery of insulin. PA-chitosan capsules were compared with tripolyphosphatePhytic acid (PA) was used as a cross-linking agent for encapsulation of insulin in a chitosan matrix for oral delivery of insulin. PA-chitosan capsules were compared with tripolyphosphate (TPP)-chitosan capsules for stable oral delivery of insulin. During 2 h incubation in simulated gastric fluid, PA-chitosan capsules prepared using pH 6, 6% PA solutions showed better stability than TPP-chitosan capsules prepared using pH 7, 6% TTP solution. PA-chitosan capsules released less than 60% of their encapsulated insulin after 24 h incubation in simulated gastrointestinal fluids. TPP-chitosan capsules showed burst release and virtually the entire insulin content was released in 12 h. Both capsule types were tested in vivo via oral drug administration using diabetic mice. PA-chitosan capsules significantly decreased blood glucose levels while TPP-chitosan capsules caused a lesser reduction. The relative pharmacological bioactivity of PA-chitosan capsules prepared was 6.4% while that of TPP-chitosan capsules was 1.1%. PA-chitosan capsules appeared to have good potential for use in oral delivery of insulin for sustained control of the blood glucose level.

• Chondrocyte distribution and cartilage regeneration in silk fibroin sponge.

  Authors: Masahiro Kawakami, Naohide Tomita, Yasuhiro Shimada, Koji Yamamoto, Yasushi Tamada, Naoyoshi Kachi, Toru Suguro

  Bio-medical materials and engineering. 21(1):53-61.

  Chondrocytes distribution and cartilage formation in three types of fibroin sponges with different average pore sizes (40-80, 80-120 and 100-140 μm) was measured. The image processing was performedChondrocytes distribution and cartilage formation in three types of fibroin sponges with different average pore sizes (40-80, 80-120 and 100-140 μm) was measured. The image processing was performed combining two methods to identify cells automatically: extraction of local maximum luminance and multi-threshold analysis. The results showed that initial accumulation of chondrocytes localized at surface area at 3 h in the small and medium-pore groups, however, the difference in the cell distributions become equivalent until 24 h after seeding. Cartilaginous tissue was well formed in each group at 21 days, and that in the smaller pore group tend to distribute at the surface area. Spherical tissues were located at the subsurface (200-600 μm below the surface) of the sponge in the medium- and large-pore groups at 21 days. Local cell aggregation was observed at 24 h at the same depth of the fibroin sponge as the spherical tissues observed at 21 days. These results suggest that the initial cell condensation process till 24 h after seeding play an important role in cartilage tissue formation.

• Alveolar bone regeneration in post-extraction socket: a review of materials to postpone dental implant.

  Authors: Roberto Porrini, Vincenzo Rocchetti, Vittorio Vercellino, Mario Cannas, Maurizio Sabbatini

  Bio-medical materials and engineering. 21(2):63-74.

  Tooth extraction usually involves alveolar bone loss and reduction in height and width of the remaining alveolar socket, owing to the physiological bone resorption. This occurrence may perform anTooth extraction usually involves alveolar bone loss and reduction in height and width of the remaining alveolar socket, owing to the physiological bone resorption. This occurrence may perform an inadequate bone profile, that make difficult orthodontic applications, compromising the functional and aesthetic restoration of dental implants. The present review will provide an update on the biological and clinical profile of materials currently in use and those under investigation, in the recovering of bone margins of edentulous sockets.

• Comparison of electrode materials for the use of retinal prosthesis.

  Authors: Niina Onnela, Hirotaka Takeshita, Yoshiuki Kaiho, Toshiya Kojima, Risato Kobayashi, Tetsu Tanaka, Jari Hyttinen

  Bio-medical materials and engineering. 21(2):83-97.

  Retinal implants may provide vision for people suffering from photoreceptor degeneration caused by different eye diseases. Electrode size in retinal implant should be decreased in order to increaseRetinal implants may provide vision for people suffering from photoreceptor degeneration caused by different eye diseases. Electrode size in retinal implant should be decreased in order to increase the resolution provided by the implant. We defined electric properties of five different electrode materials (Au, Ir-b, Ti, TiN, Pt-b) widely used in retinal prostheses. The comparison of different electrode materials requires that the electrical properties of different materials are defined using exactly the same measurement conditions and devices. Existing studies about electrode material properties are often made using slightly different measurement parameters or electrode processing conditions making the comparison between different materials difficult. Here, the electrochemical characterization included cyclic voltammetry and electrochemical impedance spectroscopy. Ir-b and Pt-b had greater charge injection capacity than other materials. The fabricated material samples showed that in this experiment the electrode diameter larger than 200 μm should be used to suppress irreversible reaction of stimulus electrodes with the needed stimulus currents. Thus, either we have to find novel electrode materials or surface treatment methods to decrease the electrode area providing increased electrode and pixel number of the prosthesis or we have to show that stimulus currents smaller than 40 μA are enough to induce phosphenes.

• Synergistic responses of superficial chemistry and micro topography of titanium created by wire-type electric discharge machining.

  Authors: Yu Kataoka, Yukimichi Tamaki, Takashi Miyazaki

  Bio-medical materials and engineering. 21(2):113-21.

  Wire-type electric discharge machining has been applied to the manufacture of endosseous titanium implants as this computer associated technique allows extremely accurate complex sample shaping withWire-type electric discharge machining has been applied to the manufacture of endosseous titanium implants as this computer associated technique allows extremely accurate complex sample shaping with an optimal micro textured surface during the processing. Since the titanium oxide layer is sensitively altered by each processing, the authors hypothesized that this technique also up-regulates biological responses through the synergistic effects of the superficial chemistry and micro topography. To evaluate the respective in vitro cellular responses on the superficial chemistry and micro topography of titanium surface processed by wire-type electric discharge, we used titanium-coated epoxy resin replica of the surface. An oxide layer on the titanium surface processed by wire-type electric discharge activated the initial responses of osteoblastic cells through an integrin-mediated mechanism. Since the mRNA expression of ALP on those replicas was up-regulated compared to smooth titanium samples, the micro topography of a titanium surface processed by wire-type electric discharge promotes the osteogenic potential of cells. The synergistic response of the superficial chemistry and micro topography of titanium processed by wire-type electric discharge was demonstrated in this study.

• FEM assisted evaluation of PMMA and Ti6Al4V as materials for cranioplasty resulting mechanical behaviour and the neurocranial protection.

  Authors: Alexander Tsouknidas, Stergios Maropoulos, Savvas Savvakis, Nikolaos Michailidis

  Bio-medical materials and engineering. 21(3):139-47.

  Recent advances in Computer Aided Design and Manufacturing techniques (CAD/CAM) have facilitated the rapid and precise construction of customized implants used for craniofacial reconstruction. DataRecent advances in Computer Aided Design and Manufacturing techniques (CAD/CAM) have facilitated the rapid and precise construction of customized implants used for craniofacial reconstruction. Data of the patients' trauma, acquired through Computer Topographies (CT), provide sufficient information with regard to the defect contour profile, thus allowing a thorough preoperative evaluation whilst ensuring excellent implant precision. During the selection, however, of a suitable implant material for the specific trauma, the mechanical aspects of the implant have to be considered. This investigation aims to assess the mechanical strength, the shock resistance and the critical deflection of cranial implants manufactured with two commonly used materials, Polymethylmethacrylate (PMMA) and Ti6Al4V. Even though the strength properties of Ti-alloys are far superior to those of PMMA, there are several aspects that may act in advantage of PMMA, e.g., it is known that discontinuities in the elastic modulus of adjoined parts (bone-implant) lead to bone resorption thus loosening the fixation of the implant over time.The implant design and fixation was the same in both cases allowing a direct comparison of the implant behavior for various loads. Finite Element Methods (FEM) assisted procedures were employed, providing a valuable insight to the neurocranial protection granted by these implants.

• Effect of calcium alginate concentration on viability and proliferation of encapsulated fibroblasts.

  Authors: Siti P M Bohari, David W L Hukins, Liam M Grover

  Bio-medical materials and engineering. 21(3):159-70.

  Alginate hydrogels have been used widely in tissue engineering for cell encapsulation for several reasons: low toxicity, the ability to gel under gentle condition and compatibility with cells. InAlginate hydrogels have been used widely in tissue engineering for cell encapsulation for several reasons: low toxicity, the ability to gel under gentle condition and compatibility with cells. In this study, we determined the effect of different concentrations of alginate on encapsulation of 3T3 fibroblast cells at two different cell seeding densities. Live/dead staining and MTT assay were performed at regular intervals up to 4 weeks. A Hoechst 33258 assay was done to validate the MTT results. There were more dead cells on day 1 for the higher concentrations of alginate while at, the lower concentration of alginate, cell proliferation and spheroid formation occurred more quickly. Furthermore, at low cell seeding density, cell proliferation was prolonged compared to the intermediate seeding density. In conclusion, by altering both alginate concentration and cell seeding density, proliferation and spheroid formation can be controlled.

• Characterization of a hydroxyapatite sputtered film subject to hydrothermal treatment using FE-SEM and STEM.

  Authors: K Ozeki, H Aoki, T Masuzawa

  Bio-medical materials and engineering. 21(3):179-89.

  Hydroxyapatite (HA) was coated onto a titanium substrate using radio frequency magnetron sputtering. The sputtered film was crystallized using a hydrothermal treatment. The films were observed usingHydroxyapatite (HA) was coated onto a titanium substrate using radio frequency magnetron sputtering. The sputtered film was crystallized using a hydrothermal treatment. The films were observed using X-ray diffractometry, field emission scanning electron microscopy (FE-SEM) and scanning transmission electron microscopy (STEM) equipped with energy dispersive X-ray spectroscopy (EDX).It was observed that the surface of the hydrothermally-treated film was covered with globular particles. The FE-SEM observations indicated that these particles were composed of columnar grains with a grain size of 20-50 nm. In the STEM cross-sectional observation of the HA-Ti interface, HA crystalline phase regions were observed, in part, in the non-crystalline phase layer of the as-sputtered film. After the hydrothermal treatment, the HA layer crystallized; the HA crystallization proceeded to a distance of 30 nm above the titanium surface. From an EDX line scan analysis, the titanium oxide layer was not observed at the HA-Ti interface of the as-sputtered film; however, in the hydrothermally-treated film, the titanium oxide layer, with a 15 nm thickness, was observed between the mixing layer and the titanium substrate. The formation of titanium oxide at the HA-Ti interface would contribute to the adhesion improvement of the sputtered film following the hydrothermal treatment.

• Evaluation of anti-vibration effectiveness of glove materials using an animal model.

  Authors: Xueyan S Xu, Danny A Riley, Magnus Persson, Daniel E Welcome, Kristine Krajnak, John Z Wu, Sandya R Govinda Raju, Ren G Dong

  Bio-medical materials and engineering. 21(4):193-211.

  Gloves with anti-vibration features are increasingly used to reduce impact vibrations or shocks transmitted to the hands of power tool operators. Selection and evaluation of the glove materials areGloves with anti-vibration features are increasingly used to reduce impact vibrations or shocks transmitted to the hands of power tool operators. Selection and evaluation of the glove materials are important steps in the designs of such gloves. In the current study, we proposed an approach to objectively evaluate the effectiveness of the glove materials using a rat-tail impact model. As a critical part of a systematic investigation, we examined the vibration reduction characteristics of typical resilient glove materials (air bladders and viscoelastic gels) and the impact vibrations transmitted to the rat tail. A special test platform that mimics impact tool vibrations was constructed and used in the experiment. A scanning laser vibrometer was used to measure the vibration at points across the platform surface under several different test conditions. The peak acceleration was found to be greatly attenuated by the glove materials, especially by using strips from a gel-filled glove. The rat tail was found to effectively absorb the high-frequency vibration. However, the glove materials and the rat tail did not reduce the frequency-weighted acceleration. The implications of the experimental results are discussed.

• Biocompatibility of 17-4 PH stainless steel foam for implant applications.

  Authors: Ilven Mutlu, Enver Oktay

  Bio-medical materials and engineering. 21(4):223-33.

  In this study, biocompatibility of 17-4 PH stainless steel foam for biomedical implant applications was investigated. 17-4 PH stainless steel foams having porosities in the range of 40-82% with anIn this study, biocompatibility of 17-4 PH stainless steel foam for biomedical implant applications was investigated. 17-4 PH stainless steel foams having porosities in the range of 40-82% with an average pore size of around 600 μm were produced by space holder-sintering technique. Sintered foams were precipitation hardened for times of 1-6 h at temperatures between 450-570 °C. Compressive yield strength and Young's modulus of aged stainless steel foams were observed to vary between 80-130 MPa and 0.73-1.54 GPa, respectively. Pore morphology, pore size and the mechanical properties of the 17-4 PH stainless steel foams were close to cancellous bone. In vitro evaluations of cytotoxicity of the foams were investigated by XTT and MTT assays and showed sufficient biocompatibility. Surface roughness parameters of the stainless steel foams were also determined to characterize the foams.

• New bioactive glass-ceramic: synthesis and application in PMMA bone cement composites.

  Authors: Hamizah Abd Samad, Mariatti Jaafar, Radzali Othman, Masakazu Kawashita, Noor Hayati Abdul Razak

  Bio-medical materials and engineering. 21(4):247-58.

  In present study, a new composition of glass-ceramic was synthesized based on the Na2O-CaO-SiO2-P2O5 glass system. Heat treatment of glass powder was carried out in 2 stages: 600 °C as the nucleationIn present study, a new composition of glass-ceramic was synthesized based on the Na2O-CaO-SiO2-P2O5 glass system. Heat treatment of glass powder was carried out in 2 stages: 600 °C as the nucleation temperature and different temperature on crystallization at 850, 950 and 1000 °C. The glass-ceramic heat-treated at 950 °C was selected as bioactive filler in commercial PMMA bone cement; (PALACOS® LV) due to its ability to form 2 high crystallization phases in comparison with 850 and 1000 °C. The results of this newly glass-ceramic filled PMMA bone cement at 0-16 wt% of filler loading were compared with those of hydroxyapatite (HA). The effect of different filler loading on the setting properties was evaluated. The peak temperature during the polymerization of bone cement decreased when the liquid to powder (L/P) ratio was reduced. The setting time, however, did not show any trend when filler loading was increased. In contrast, dough time was observed to decrease with increased filler loading. Apatite morphology was observed on the surface of the glass-ceramic and selected cement after bioactivity test.

• The effect of E-beam engineered surface structures on attachment, proliferation and differentiation of human mesenchymal stem cells.

  Authors: J Elizabeth Biemond, G Hannink, N Verdonschot, P Buma

  Bio-medical materials and engineering. 21(5):271-9.

  Electron beam melting (E-beam) is a new technology to produce 3-dimensional surface topographies for cementless orthopedic implants. The effect of two newly designed highly porous E-beam engineeredElectron beam melting (E-beam) is a new technology to produce 3-dimensional surface topographies for cementless orthopedic implants. The effect of two newly designed highly porous E-beam engineered surface structures (cubic and star) on attachment, proliferation and differentiation of human mesenchymal stem cells (hMSCs) was investigated and compared to a solid sandblasted control. SEM analysis showed that the E-beam structures allowed cells to attach and spread. Proliferation on the new surface structures was comparable to the solid control. Furthermore, differentiation on the 3D structures was comparable to the control specimen. When culturing 300,000 cells for 10 days, the cubic structure showed a significantly higher differentiation rate compared to the sandblasted specimen. We conclude that the results for attachment, proliferation and differentiation of mesenchymal stem cells on the newly engineered 3-dimensional E-beam surface topographies are promising. In vivo experiments are necessary to assess the bone ingrowth potential of the new surface structures.

• Low-modulus PMMA bone cement modified with castor oil.

  Authors: Alejandro López, Andreas Hoess, Thomas Thersleff, Marjam Ott, Håkan Engqvist, Cecilia Persson

  Bio-medical materials and engineering. 21(5):323-32.

  Some of the current clinical and biomechanical data suggest that vertebroplasty causes the development of adjacent vertebral fractures shortly after augmentation. These findings have been attributedSome of the current clinical and biomechanical data suggest that vertebroplasty causes the development of adjacent vertebral fractures shortly after augmentation. These findings have been attributed to high injection volumes as well as high Young's moduli of PMMA bone cements compared to that of the osteoporotic cancellous bone. The aim of this study was to evaluate the use of castor oil as a plasticizer for PMMA bone cements. The Young's modulus, yield strength, maximum polymerization temperature, doughing time, setting time and the complex viscosity curves during curing, were determined. The cytotoxicity of the materials extracts was assessed on cells of an osteoblast-like cell line. The addition of up to 12 wt% castor oil decreased yield strength from 88 to 15 MPa, Young's modulus from 1500 to 446 MPa and maximum polymerization temperature from 41.3 to 25.6°C, without affecting the setting time. However, castor oil seemed to interfere with the polymerization reaction, giving a negative effect on cell viability in a worst-case scenario.

• Honeycomb form β-tricalcium phosphate induces osteogenesis by geometrical property with BMSC.

  Authors: Kimitoshi Yagami, Tatsuo Shirota, Satoru Shintani, Mitsuori Mayahara, Mikio Nishizawa, Shigeru Yanagisawa, Rachel Sammons, Yoshinori Kuboki

  Bio-medical materials and engineering. 21(5):291-306.

  To establish an effective method for bone augmentation, we introduced a new honeycomb-like β-tricalcium phosphate (H-β-TCP) with BMP-2 as a scaffold, whose unique geometrical properties induceTo establish an effective method for bone augmentation, we introduced a new honeycomb-like β-tricalcium phosphate (H-β-TCP) with BMP-2 as a scaffold, whose unique geometrical properties induce osteoblastic differentiation of autologous bone marrow mesenchymal stem cells (BMSCs).A total of six beagle dogs from 6 to 7 years old were used for this study. BMSCs were cultured with autologous serum and BMP-2 on H-β-TCP. Differentiation to osteoblasts was demonstrated in vitro and exo vivo. Scanning electron microscopy revealed formation and calcification of a matrix-like structure within the H-β-TCP tunnels in BMSC culture. Moreover, treatment of BMP-2 promoted osteoblastic differentiation of BMSCs in H-β-TCP in a diffusion chamber. These results indicated that H-β-TCP may be a useful tool for construction of functional artificial bone.

• Study the effect of polymerization temperature in the release of antibiotic from bone cement.

  Authors: Ching-Lung Tai, Siu-Lian Tsai, Yu-Han Chang, Pang-Hsin Hsieh

  Bio-medical materials and engineering. 21(5):341-6.

  Antibiotic-loaded bone cement is widely used to treat musculoskeletal infections. Here we tested whether the curing temperature affected pore size of the cement and antibiotic release. Bone cementAntibiotic-loaded bone cement is widely used to treat musculoskeletal infections. Here we tested whether the curing temperature affected pore size of the cement and antibiotic release. Bone cement containing vancomycin was cured at 3 temperatures (50, 25 and 0°C). The solidified vancomycin-loaded cement was stored for 1-week at 25 and 5°C and then assayed for antibiotic release. We found that a significantly higher proportion of vancomycin was released from cement cured at 0°C versus that cured at 50°C, and that lower storage temperature also increased antibiotic release.

• Parameter optimization for the visco-hyperelastic constitutive model of tendon using FEM.

  Authors: C Y Tang, G Y F Ng, Z W Wang, C P Tsui, G Zhang

  Bio-medical materials and engineering. 21(1):9-24.

  Numerous constitutive models describing the mechanical properties of tendons have been proposed during the past few decades. However, few were widely used owing to the lack of implementation in theNumerous constitutive models describing the mechanical properties of tendons have been proposed during the past few decades. However, few were widely used owing to the lack of implementation in the general finite element (FE) software, and very few systematic studies have been done on selecting the most appropriate parameters for these constitutive laws. In this work, the visco-hyperelastic constitutive model of the tendon implemented through the use of three-parameter Mooney-Rivlin form and sixty-four-parameter Prony series were firstly analyzed using ANSYS FE software. Afterwards, an integrated optimization scheme was developed by coupling two optimization toolboxes (OPTs) of ANSYS and MATLAB for estimating these unknown constitutive parameters of the tendon. Finally, a group of Sprague-Dawley rat tendons was used to execute experimental and numerical simulation investigation. The simulated results showed good agreement with the experimental data. An important finding revealed that too many Maxwell elements was not necessary for assuring accuracy of the model, which is often neglected in most open literatures. Thus, all these proved that the constitutive parameter optimization scheme was reliable and highly efficient. Furthermore, the approach can be extended to study other tendons or ligaments, as well as any visco-hyperelastic solid materials.

• Genetic diagnosis of cancer by fuzzy-rough gene selection and the complementary hierarchical fuzzy classifier.

  Authors: Zahra Shaeiri, Reza Ghaderi

  Bio-medical materials and engineering. 21(1):37-52.

  Gene expression data have extremely high dimensionality with respect to traditional classifiers which causes not to be used efficiently. In this paper a Fuzzy-Rough Gene Selection and ComplementaryGene expression data have extremely high dimensionality with respect to traditional classifiers which causes not to be used efficiently. In this paper a Fuzzy-Rough Gene Selection and Complementary Hierarchical Fuzzy classifier (FRGS-CHF) to classify the gene expression data as a new methodology is proposed. First, some relevant genes are selected using fuzzy-rough attribute selection method. After removing redundant genes, a new complementary hierarchical fuzzy classifier is proposed. The complementary learning mechanism refers to positive and negative learning which are found in the human brain hippocampus. FRGS-CHF is made-up of two parallel hierarchical fuzzy systems; the first is trained with positive samples whilst the other is treated with negative samples. In contrast to many other methods such as statistical or neural networks, FRGS-CHF provides greater interpretability. It does not rely on the assumption of underlying data distribution. Using complementary and hierarchical approaches, the proposed method exploits the lateral inhibition between output classes and considers the problem as a multidimensional problem. Benchmarked datasets are used to demonstrate the validity and advantages of the proposed method over the other existing methods in terms of the accuracy, better transparency, time efficiency together with fewer fuzzy rules and parameters.

• Osteoblast differentiation and disinfection induced by nitrogen plasma-treated surfaces.

  Authors: Wei Zhang, Huaiyu Wang, Ayako Oyane, Hideo Tsurushima, Paul K Chu

  Bio-medical materials and engineering. 21(2):75-82.

  Plasma technology is widely employed to tailor the surface chemistry of polymeric biomaterials. In this work, nitrogen-containing functional groups were generated on a polymer surface by N₂ plasmaPlasma technology is widely employed to tailor the surface chemistry of polymeric biomaterials. In this work, nitrogen-containing functional groups were generated on a polymer surface by N₂ plasma immersion ion implantation (PIII). We evaluated the abilities of the resulting surface to inhibit bacterial growth and to enhance osteoblast differentiation from the perspective of bone tissue engineering. Our results demonstrate that the N₂ PIII-treated polymer surface exhibits antibacterial properties against Escherichia coli. Moreover, the N₂ PIII-treated polymer surface has the ability to enhance differentiation of osteoblasts. N₂ PIII-treated polymer surface may therefore be useful in bone tissue engineering.

• Electrospun chitosan-gelatin nanofiberous scaffold: fabrication and in vitro evaluation.

  Authors: Javad Jafari, Shahriar Hojjati Emami, Ali Samadikuchaksaraei, Mohammad Ali Bahar, Fazel Gorjipour

  Bio-medical materials and engineering. 21(2):99-112.

  In this study, chitosan and gelatin solutions were blended at five different ratios. Samples were fed into electrospinning apparatus to produce non-woven nanofibrous mats. Scanning electronIn this study, chitosan and gelatin solutions were blended at five different ratios. Samples were fed into electrospinning apparatus to produce non-woven nanofibrous mats. Scanning electron microscopy (SEM) showed that the low-viscosity sample with 30% chitosan and 70% gelatin (sample 30/70) formed the least amount of beads and droplets and yielded fibers with the highest morphological uniformity. To examine the effect of processing parameters on fibers morphology and nanofibers diameter, flow rate, voltage and distance between needle to the collector were changed in the sample 30/70. SEM revealed that high voltages (25 kV) and flow rates (1.5 ml·h⁻¹) decrease the uniformity of fibers and lead to bead and droplet formation. It has also shown that the distance between the tip and the collector have no significant effect on fibers' structure. The values of 15 kV (voltage), 0.2 ml·h⁻¹ (flow rate) and the fixed distance of 15 cm were identified as the optimal electrospinning conditions, which produce fibers with a mean diameter of 180±20 nm. Fourier transform infrared (FTIR) experiment revealed an increase in N-H bending and decrease in C-O stretching vibration in both chitosan and gelatin at 1060 and 1148 cm⁻¹. The in vitro biocompatibility tests performed with human skin fibroblasts showed excellent cell proliferation (MTT assay) and attachment (SEM) on these scaffolds confirming its highly acceptable biological properties.

• Influence of water/O₂ plasma treatment on cellular responses of PCL and PET surfaces.

  Authors: Hilal Türkoğlu Şaşmazel, Sezin Aday, Sorin Manolache, Menemşe Gümüşderelioğlu

  Bio-medical materials and engineering. 21(2):123-37.

  In this study, low pressure water/O₂ plasma treatment was performed in order to obtain COOH functionalities on the surface of poly-ε-caprolactone (PCL) membranes as well as non-woven polyester fabricIn this study, low pressure water/O₂ plasma treatment was performed in order to obtain COOH functionalities on the surface of poly-ε-caprolactone (PCL) membranes as well as non-woven polyester fabric (NWPF) discs. The plasma treatments were performed in a cylindrical, capacitively coupled RF-plasma-reactor and then following steps were performed: in situ (oxalyl chloride vapors) gas/solid reaction to convert -OH functionalities into -COCl groups; and hydrolysis under open laboratory conditions using air moisture for final-COOH functionalities. COOH and OH functionalities on modified surfaces were detected quantitatively by using fluorescent labeling technique and an UVX 300G sensor. Electron spectroscopy for chemical analysis (ESCA) was used to evaluate the relative surface atomic compositions and the carbon and oxygen linkages located in non-equivalent atomic positions of untreated and modified surfaces. Atomic force microscope (AFM) analysis showed that nanoscale features of the PCL surfaces are dramatically changed during the surface treatments. Scanning electron microscopy (SEM) results indicated the changes in the relatively smooth appearance of the untreated NWPF discs after the plasma treatment. Periodontal ligament (PDL) fibroblasts were used in cell culture studies. Cell culture results showed that plasma treated PCL membranes and NWPF discs were favorable for the PDL cell spreading, growth and viability due to the presence of functional groups and/or nanotopographies on their surfaces.

• Nano-vibration effect on cell adhesion and its shape.

  Authors: Yukiko Ito, Tsuyoshi Kimura, Yusuke Ago, Kwangwoo Nam, Kaori Hiraku, Kozo Miyazaki, Toru Masuzawa, Akio Kishida

  Bio-medical materials and engineering. 21(3):149-58.

  Extracellular physical features of underlying the adhesive substrate affect cell adhesion to it substrate. In this study, the effects of vibration, a type of artificial physical stimulation, on theExtracellular physical features of underlying the adhesive substrate affect cell adhesion to it substrate. In this study, the effects of vibration, a type of artificial physical stimulation, on the adhesion of mouse L929 cells, mouse embryonic fibroblasts (MEFs), HeLa cells and human umbilical vein endothelial cells (HUVECs) are reported. A nano-vibration system was designed to produce nanometer-scale vibration. When L929 cells, HeLa cells, and HUVECs were subjected to vibration at 100 Hz and 1 kHz, they were not affected. On the other hand, in MEFs, the adherent cells were increased and changed their shape remarkably in response to 1 kHz vibration. To investigate the MEFs' sensitivity to vibration in detail, the cells shape was classified into four types; round, stellate, filopodia-formed and lamellipodia-formed. In serum addition culture, 1 kHz vibration increased the number of filopodia-formed cells but decreased lamellipodia cells. Furthermore, the preliminary cDNA microarray experiments showed that expression of genes which regulate cytoskeleton were changed by vibration stimulation. These results suggest that vibration could affect cell adhesion and the determination cell shape.

• Frequency response of blood vessel wall with atherosclerosis and aneurysm.

  Authors: A Toshimitsu Yokobori, Masataka Ichiki, Yuki Tomono, Daisuke Tanaka, Takashi Kanno, Ryuji Sugiura, Yuji Ohtomo, Masatoshi Ito, Seiichi Ohgoshi

  Bio-medical materials and engineering. 21(3):171-7.

  This research was conducted to investigate frequency response of blood vessel wall. The principal frequency of blood vessel wall, f1 was found to decrease with progression of atherosclerosis andThis research was conducted to investigate frequency response of blood vessel wall. The principal frequency of blood vessel wall, f1 was found to decrease with progression of atherosclerosis and irregularity of the vibration trajectory of blood vessel wall was found to increase. When an aneurysm appeared, a new vibration wave was found to appear in the high frequency region, f2. When the aneurysm wall has enough strength, intensity of high frequency wave was found to increase. However, it decreases with decrease in the strength of aneurysm wall. The visco-elastic deterioration of blood vessel wall was found to well correlate with the changing characteristics of f1. A two-dimensional representation of f1 and f2 was conducted which tracks the progression of atherosclerosis and aneurysm. It will enable us to diagnose the introduction period of operation of blood vessel wall of atherosclerosis with an aneurysm.

• Influence of water/O2 plasma treatment on cellular responses of PCL and PET surfaces.

  Authors: Hilal Turkoglu Sasmazel, Sezin Aday, Sorin Manolache, Menemse Gumusderelioglu

  Bio-medical materials and engineering. 21(3):191.

  Related article: http://iospress.metapress.com/content/uk80372845742282/

• A novel electrical potential sensing method for in vitro stent fracture monitoring and detection.

  Authors: Chan-Hee Park, Leonard D Tijing, Yeoheung Yun, Cheol Sang Kim

  Bio-medical materials and engineering. 21(4):213-22.

  This article describes a preliminary investigation and prototype fabrication of a novel potential sensing method to continuously monitor vascular stent fractures. A potential measurement systemThis article describes a preliminary investigation and prototype fabrication of a novel potential sensing method to continuously monitor vascular stent fractures. A potential measurement system consisting of Wheatstone bridge circuit and signal conditioning circuit was designed for the cardiovascular stent durability and fatigue test. Each end of a bare and polyurethane-covered Nitinol vascular stent was electrically connected to the potential measurement system and then immersed either in simulated body fluid (SBF) media or distilled water at 36.4 ± 1 °C. When the stent experienced fracture (i.e., a cut), its electrical potential decreased with an increase in electrical resistance. This method successfully measured fractures in the stent regardless of location. Furthermore, the number of cycles at the onset of stent fracture was accurately detected and continuously monitored using this technique. Thus, the present fracture detection method, which to our knowledge is the first ever report to use electrical potential measurement for stent durability test, gives a fast, real-time, accurate and efficient detection of fractures in stent during in vitro fatigue and durability test.

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