Nader Nezafati

Materials and Energy Research Center | MERC · Department of Nanotechnology and Advanced Materials

Fluoride varnishes or gels have been advised by dentists for any tooth decay. Fluoride varnishes can be assessed based on various factors such as surface micro-hardness. The present study is aimed to evaluate the micro-hardness of enamel surfaces after the application of different types of fluoride varnishes. Three different fluoride varnish compos...

Polymeric and tetracalcium phosphate (TTCP)-containing polymeric scaffolds were fabricated using a freeze-drying technique, with a homogenous solution of hydroxyethyl cellulose (HEC)/hyaluronic acid (HA)/gelatin (G) or suspension of 15 or 20% TTCP) particles in HEC/HA/G solution. The morphology, phase composition, chemical bands, and swelling behav...

In the present comparative study, gelatin microspheres (GMs) were prepared by Emulsification-solvent-extraction method using well-known crosslinker: Glutaraldehyde (GA) and biocompatible silane-coupling agent: Glycidoxypropyltrimethoxysilane (GPTMS). Crosslinking with GA was done by a definite and common procedure, while GPTMS crosslinking potency...

Gum tragacanth (GT) as an interesting biocompatible hydrophilic polysaccharide along with widely-used bioactive glass nanoparticles (BGNPs) could possibly provide a novel and promising combination as bone tissue engineering (BTE) scaffolds. Accordingly, in the present study, composite scaffold formulations of GT matrix and increasing amounts of BGN...

In this study, azide and alkyne moieties were introduced to the structure of citric acid-modified hydroxyethyl cellulose (HEC) and then through a bioorthogonal click chemistry method: Strain-promoted azide-alkyne cycloaddition, a novel crosslinked HEC scaffold (click sample) was obtained. Chemical modifications and successful crosslinking of the sa...

One of the major challenges in bone tissue engineering is the preparation of highly interconnected porous scaffolds with suitable mechanical properties. Synthetic scaffolds used in medicine are usually made of single-phase of ceramic or polymer. However, the combination of these materials with graphene-based nanofillers can produce scaffolds with i...

Nanotechnology has many potential applications in cancer treatment. For example, nano-drug delivery systems (NDDS) with high bioavailability, biodegradability, and biocompatibility have been developed, in order to increase the therapeutic effects of anti-cancer drugs. Among these NDDS, high-performance hydroxyapatite nanoparticles are rapidly advan...

The purpose of this study was to prepare and compare a hydroxyethyl cellulose/hyaluronic acid (HEC/HA)-based scaffold with and without gelatin for the treatment of second-degree partial-thickness burns. The scaffolds were prepared by freeze-drying method from the aqueous solutions of the mentioned polymers. Microstructural examination by scanning e...

The purpose of this study was to prepare a hydroxyethyl cellulose/hyaluronic acid (HA/HEC) based scaffold, with or without 5% tetracalcium phosphate, and compare them for accelerating wound healing. The samples were prepared by freeze-drying method from the mentioned solutions. Scanning electron microscopy (SEM) micrographs indicated that the avera...

The purpose of this study was to fabricate a polymeric scaffold that contains tetra-calcium phosphate for accelerating chicken embryo development by increasing blood formation. The results showed that the 8 days old embryo had a 9 days old embryo’s appearances with higher height and weight in comparison to the control embryo. It means that the prep...

The purpose of this study was to prepare a hyaluronic acid/hydroxyethyl cellulose (HA/HEC) based scaffold for accelerating wound healing.

This study investigates the effect of simultaneous incorporation of crosslinked gelatin microspheres (GMs) and hydroxyapatite whiskers (HAWs) on the compositional characteristics, phase evolution, setting time, microstructure and mechanical properties of the calcium phosphate cement (CPC) matrix. In addition, the mechanical properties of composite...

The purpose of this study was to fabricate gelatin (G) and hydroxyethyl cellulose (HEC) scaffolds as promising for skin tissue engineering. Therefore, crosslinking is essential to prepare the mentioned scaffolds. ɣ -Glycidoxypropyltrimethoxysilane (GPTMS) was added to polymeric solutions as a cross-linker agent and then freeze-dried. Scanning elect...

In this study, novel calcium phosphate cement (CPC) composites were prepared by simultaneous incorporation of porogenic crosslinked gelatin microspheres (GMs) and reinforcing hydroxyapatite whiskers (HAWs) into the CPC matrix and the effects of the mentioned additives on the compositional characteristics, phase evolution, setting time, microstructu...

Resin-based pit-and-fissure sealants (flowable resin composites) were formulated using bisphenol-A-glycerolatedimethacrylate (Bis-GMA)-triethylene glycol dimethacrylate-(TEGDMA)-diurethanedimethacrylate (UDMA) mixed monomers and multiple fillers, including synthetic strontium fluoride (SrF2) nanoparticles as a fluoride-releasing and antibacterial a...

In the present study, different weight ratios of electrospun bioactive glass nanofibers (3, 5, 10, 15, 25 and 35 wt%) (BGF) were added to calcium sulfate cement (CSC). Physical and mechanical properties of CSC/BGF composites were evaluated and compared with CSC. Initial and final setting times of CSC were reduced from 12 to 27 min to 6 and 21 min b...

High (cation/Ca+cation=16 mol.%) and low (cation/ca+cation=4.76 mol.%) concentrations of Mg 2+ , Zn 2+ and Sr 2+ , as divalent cations with interesting biological properties were tried to incorporate into the structure of well-known bioceramic: hydroxyapatite (HA). An established hydrothermal synthesis method was employed for preparation of HA in w...

Novel chitosan scaffolds containing different weight ratios of electrospun hydroxyapatite nanofibers (n‐HA) were fabricated. The fibers possessed diameters in the range of 110–170 nm. A fixed concentration of glycidyloxypropyl‐trimethoxysilane (GPTMS) as a crosslinking agent was added to the chitosan solution (CG). The porosity percentage was incre...

Injectable composite pastes were prepared using melt‐derived 45S5 bioactive glass and tragacanth crosslinked by (3‐glycidyloxypropyl)trimethoxysilane (GPTMS). The effect of powder to liquid ratio (P:L = 1.0:2.0–1.0:2.5) and GPTMS/tragacanth ratio (0.0–1.5) on the injectability, swelling behavior, rheology, bioactivity, and cellular behavior of the...

The feasibility of incorporating high (M/M+Ca = 16 mol. %) and low (M/M+Ca = 4.76 mol. %) concentrations of Mg ²⁺ , Zn ²⁺ and Sr ²⁺ , as divalent cations with interesting biological properties, into the structure of well-known bioceramic: hydroxyapatite (HA) was carefully assessed. An established hydrothermal synthesis method was employed for prepa...

The aim of the present study was to investigate the effect of click chemistry reactants on morphology and physico-chemical properties of alpha tricalcium phosphate (α-TCP)-based powders. The powders were synthesized by solid-state reaction. The powders were modified with azide and cycloalkyne to form triazole as a consequence of reactions of these...

Injectable hydrogels and biodegradable nanoparticles are using in tissue engineering applications and drug delivery systems. To improve physiochemical properties of biomaterials and to develop their applications, hybrid systems consist of hydrogels, and biodegradable nanoparticles were synthesized. In this study, hybrid systems based on double cros...

In the present comparative study, gelatin microspheres (GMs) were prepared by emulsification-solvent-extraction method using well-known crosslinker: glutaraldehyde (GA) and biocompatible silane-coupling agent: glycidoxypropyltrimethoxysilane (GPTMS). Crosslinking with GA was done by a definite and common procedure, while GPTMS crosslinking potency...

In the present study, the effect of adding different concentrations of silicon on physical, mechanical and biological properties of a synthesized aqueous precipitated eggshell-derived hydroxyapatite (e-HA) was evaluated. No secondary phases were detected by X-ray diffraction for the specimens e-HA and e-HA containing silicon (Si-e-HAs) before and a...

در مهندسی بافت داربست زیست ماده از جنس پلیمرهای طبیعی به علت خواص زیست فعالی، تعاملات بهتر با سلول ها را به وجود می آورند که به آنها اجازه می دهد تا عملکرد سلول ها را در سیستم بیولوژیکی افزایش دهند]1[. یکی از این پلیمرها، هیدروکسی اتیل سلولز می باشد که در این تحقیق هیدروکسی اتیل سلولز با یک عامل سیلانی طی زمان ها (18 ساعت و 24 ساعت و 30 ساعت) و درص...

S53P4 bioactive glass nanoparticles (BGn) were prepared by the melting-quenching method at 1400 °C followed by ball milling. The prepared glass nanoparticles were used for surface decoration of poly-L-lactic acid (PLLA) nanofibers fabricated by electrospinning method. The microstructure, morphology and chemical functional groups of the nanomaterial...

Biocompatible, biodegradable, non-toxic and non-carcinogenic gelatin nanoparticles, containing Tramadol HCl as a model drug, were prepared by the eater-in-oil nanoemulsion procedure. Sorbitan monooleate (span 80) and tween 80, glutaraldehyde and ethyl acetate were used as the surfactant, cross-linker and continuous phase, respectively. The obtained...

Strontium fluoride (SrF2) nanoparticles were synthesized using strontium chloride-choline chloride-water deep eutectic system at 80 °C. XRD, FESEM, TEM, EDS and Raman spectroscopy were employed to characterize the synthesized nanoparticles. The analytical results confirmed the synthesis of SrF2 nanoparticles crystallized in the cubic crystal system...

Iron and cobalt materials have attracted enormous interest as low-cost alternatives to noble-metal catalysts able to catalyse oxygen reduction reaction. Here, the effect of the heteropolyacid H3PMo12O40 (HPMo) into the structure of new composites formed by Fe, Co and reduced-graphene oxide/chitosan (rGOCS) has been investigated. Chitosan was used a...

In the present study, hydroxyapatite nanofibers were synthesized by electrospinning. The main focus is based on the effect of adding various ratios of calcium phosphate (Ca-P) sol to polymeric solutions of PVA and PVP with a fixed concentration of 10 and 15% (w/v), respectively, on the morphology and the diameter of the electrospun nanofibers. The...

Electrospinning method was employed for fabrication of SiO2-CaO-P2O5 bioactive glass (BG) nanofibers, poly-l-lactic acid (PLLA) nanofibers and nanocomposite scaffolds fabricated from as-prepared nanofibers. Characterization of the prepared nanofibers and scaffolds by XRD, FTIR, and SEM techniques revealed the formation of nanofibers with mean diame...

Objective(s): Three-dimensional structures such as nanofibrous scaffolds are being used in biomedical engineering as well as provide a site for cells to attach and proliferate leading to tissue formation. In the present study, poly(vinyl pyrrolidone) (PVP)/ poly(vinyl alcohol)(PVA) hybrid nanofibrous scaffold was synthesized by electrospinning. Mat...

Gelatin microspheres (GMs) using various concentrations of epoxypropoxy-propyl-trimethoxysilane (EPPTMS) as a crosslinking agent were prepared. Since the crosslinking agent content and manufacturing conditions are crucial factors in the characteristics of the microspheres, this study was carried out to evaluate the effect of processing variables on...

In this paper, nanostructured carbonated hydroxyapatite powder was synthesized using biomimetic method. Physical properties and morphological features of the powder was studied using appropriate techniques such as BET, TEM, XRD and FTIR. The powder was separately mixed with 3 wt. % solutions of either sodium alginate or chitosan to form different p...

Ternary (%mol) (64SiO2-31CaO-5P2O5) system of sol-gel derived bioactive glass fibers was prepared by electrospinning method. X-ray Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and nitrogen adsorption test (BET) analyses were performed to investigate the phase and chemical group of the composition, morphology of...

Silver doped-bioactive glass coatings offer the possibility of bioactivation, corrosion protection and infection prevention of metallic implants. A certain composition of glass (54SiO2–36CaO–8P2O5–2Ag2O (wt %)) was coated on titanium substrate using dip coating method by 1 cm/min withdrawal rate with controlling the effective factors like viscosity...

Titanium alloys have been extensively used as promising implant materials. The anodic oxide layer on the surface of this alloy can be a compact, porous or a tubular structure, which has a direct impact on the final characteristics of the implants. In this study, nano topographic oxide arrays were synthesized on the surface of titanium substrates us...

Tumors consist of a heterogeneous population of cancer cells carrying multiple genetic mutations. During the past few decades, efforts have focused on curing cancer using various methods. However, traditional cancer therapies still carry some drawbacks, such as limited application for only a few cancer types, killing of normal cells, poor specif...

This study aims to detect the optimum antibacterial activity of silver-doped bioactive glasses (Ag-BGs) for prevention of post-transplant infections in tissue engineering. The results have shown that the Ag-BG samples had broad-spectrum antibacterial efficacy in an Ag concentration-dependent manner. The 2% Ag-BG had the highest effect during the fi...

In the present research, merwinite (M) scaffolds with and without nano-titanium dioxide (titania) were synthesized by water-based freeze casting method. Two different amounts (7.5 and 10 wt%) of n-TiO2 were added to M scaffolds. They were sintered at temperature of 1573.15°K and at cooling rate of 4°Kmin(-1) . The changes in physical and mechanical...

In the present study, gelatin-based hybrid fibrous scaffolds with and without silane agent (Epoxypropoxy-propyl-trimethoxysilane) were synthesized by electrospinning method. The effect of different concentrations of silane agent on morphology of the scaffolds was investigated. Scanning electron microscope observations showed that using the agent in...

Bioinorganics and the use of metal ions in the synthesis and design of new materials have received considerable attention with regard to use as new biomaterials. One of the important roles of metal ions is the control of dissolution in biomaterials, which has an influence on their biological and chemical properties. Up until now, metal ions such as...

In this research, sol–gel-derived nanostructured calcium magnesium silicate (merwinite)-based scaffolds were fabricated by water-based freeze casting method. The effect of cooling rate and sintering temperature on pore sizes and mechanical characteristics of the scaffolds was studied. Microstructure and surface morphology of scaffolds were also obs...

The need for bone repair has increased as the population ages. In this research, calcium phosphate cements, with and without chitosan (CS) and hyaluronic acid (HA), were synthesized. The composition and morphological properties of cements were evaluated by X-ray diffraction and scanning electron microscopy. The acellular in vitro bioactivity reveal...

In the present research, strontium containing nano-bioactive glass (NBG-Sr) was synthesized by sol-gel method. The morphology was analyzed by transmission electron microscope (TEM). Different amounts (0.5 to 5 wt%) of NBG-Sr were then added to biphasic calcium phosphate (BCP). They were sintered at different temperatures, i.e., 1100, 1200 and 13...

Calcium phosphate cements (CPCs) have been used in a number of medical and dental procedures due to their excellent osteoconductivity and bone replacement capability. However, the low mechanical properties of CPCs prohibit their usage in many unsupported defects and stress bearing locations. Bioactive glass fiber (BGF) reinforced-CPC with enhanced...

Ag‏ ions are known for their antibacterial effects. Ag containing silicate glasses have been extended to create bioactive glasses exhibiting inhibitory effects on bacterial growth using different techniques. In this work, calcium and calcium/silver silicophosphate glasses were synthesized from the sol–gel process and their physico-chemical and in v...

In the present study, a bioceramic-based composite was prepared by sintering compacts made up of mixtures of hydroxyapatite (HA) and sol–gel-derived bioactive glass (64SiO2-26CaO-5MgO-5ZnO) (based on mol%) powders. HA powder was mixed with different concentrations of the glass powders up to 30 wt.%. The effect of adding bioactive glass powder to HA...

Dycal® is a paste-paste calcium hydroxide dental cement uses as pulp capping and liner in dentistry. First paste (base paste) contains titanium dioxide and barium sulphate in glycol disalicylate and second paste (catalyst paste) contains calcium hydroxide, zinc oxide and zinc stearate in ethyl toluene sulphonamide. Equal amounts of base and catalys...

In the present study, a bioceramic-based composite with remarkable mechanical properties and in vitro apatite forming ability was synthesized by sintering compacts made up of mixtures of hydroxyapatite (HA) and sol-gel derived bioactive glass (64SiO2-26CaO-5MgO-5ZnO) (based on mole %). HA was synthesized through co-precipitation method. The stabili...

In this study, a calcium phosphate scaffold of hydroxyapatite (HAp) and dicalcium phosphate dihydrate (DCPD) for application in osteoconductive and osteoinductive scaffolds was synthesized and characterized. The important note is that the prepared composites converted to HAp/tricalcium phosphate (TCP) after heat-treatment. This class of composites...

Human beings are often infected by microorganisms in the living environment. Among various natural and inorganic substances, silver or silver ions have a powerful antibacterial activity. In the present study, the bioactivity and antibacterial activity of the SiO2–CaO–P2O5–Ag2O was compared with that of its ternary counterpart glass system (as a con...

Today, porous nanocomposite scaffolds play a key role in tissue engineering approaches and new processing methods and materials are constantly being developed to cater for the wide range of specifications and requirements. In addition, providing a structural support while maintaining bioactivity is one of the most important goals for these scaffold...

Basic drawbacks of calcium phosphate cements (CPCs) are the brittleness and low strength behavior which prohibit their use in many stress-bearing locations, unsupported defects, or reconstruction of thin bones. Recently, to solve these problems, researchers investigated the incorporation of fibers into CPCs to improve their strength. In the present...