Hydroxyapatite Gelatin Research Articles

Drug loading of tannic acid crosslinked hydroxyapatite/gelatin composites via spray dryer and kinetic studies

The present study aims at studying the loading and release of 5-Fluorouracil (5-FU) drug from hydroxyapatite/gelatin (HAp-GEL) composites. Composites were produced in the presence of simulated body fluid (SBF) at pH 7.4 and 37 °C implementing tannic acid (TA) as a cross-linking agent. HAp-GEL composites were characterized by X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. 5-FU was loaded on HAp-GEL composites via spray dryer through encapsulation. Drug release kinetics studies revealed that 5-FU release from HAp-GEL composites were best fitted to first order kinetic model with R2 values in the range of 0.85–0.98. Gelatin and TA contents of the composites were found to affect the release profiles and initial burst values, with higher initial burst values at greater gelatin contents. pH dependent release of 5-FU was observed from produced HAp-GEL composites with higher release at physiological pH (7.4) conditions. Current study suggest that produced 5-FU loaded HAp-GEL composites hold potential as carrier for 5-FU drug in clinical applications.

Evaluation of a hydroxyapatite-crosslinked fish gelatin membranes

Background/purposePorcine collagen is widely used in regenerative therapies to generate membranes for bone augmentation. However, porcine or bovine gelatin or collagen is often not appropriate for patients with creed and religious beliefs or for allergic reasons. In this study, we evaluated the potential of fish gelatin to generate membranes. Materials and methodsFish gelatin and hydroxyapatite (HAp) were used at three different ratios (2:0, 2:1, 2:1.5, and 2:2) to prepare gelatin-hydroxyapatite (G-HAp) membranes via freeze-drying and heat-crosslinking. The surface morphology and cell attachment of G-HAp membranes were observed using scanning electron microscopy and confocal laser microscopy. G-HAp membrane was placed at the bottom of a well plate, and MC3T3-E1 cells were seeded on it. Cell viability and cytotoxicity were tested after 1 and 3 days of culture. Alkaline phosphatase (ALP) and alizarin red staining was performed at 10 and 21 days, respectively. ResultsViability of cells on G-HAp membrane with the gelatin:HAp ratio of 2:1.5 was significantly higher than that on membranes with other gelatin:HAp ratios. ALP and alizarin red staining showed that ALP-positive areas and calcium deposition were the highest on G-HAp membrane with the gelatin:HAp ratio of 2:1. These membranes showed negligible cytotoxicity. ConclusionFish-derived G-HAp membranes have the potential to promote osteogenic differentiation of MC3T3-E1 cells with negligible cytotoxicity.

Morphological and Mechanical Study of Gelatin/Hydroxyapatite Composite based Scaffolds for Bone Tissue Regeneration

<p>Gelatin-Hydroxyapatite (GHA) composite has been synthesized as a scaffold in bone tissue engineering. The purpose of this study was to find the optimal composition of the GHA scaffold composite which has the best mechanical properties. The independent variable in this study was the composition of HAp. Hydroxyapatite was synthesized by precipitation method from Ca(OH)<sub>2</sub> and (NH<sub>4</sub>)<sub>2</sub>HPO<sub>4</sub> as raw materials. Scaffold from GHA Composite was made by freeze-drying technique with freezing time for 8 hours at -80º C and drying with lyophilizer. The results were characterized using XRD, optical microscopy and tested for compressive strength. The results of the XRD showed that there was no change in a compound or the formation of new bonds on the GHA scaffold when it became a composite which was indicated by the absence of new peaks. It is also known that the peaks decrease in intensity as the amount of polymer in the composite increases. The highest degree of crystallinity was found in the 1:3 GHA sample because it had the highest concentration of HAp. The results of observations with an optical microscope showed that the most homogeneous pore surface morphology was GHA 1:2 with an average pore size of 225.12 ± 16.57 μm. From the results of the compressive strength test, the best value for the 1:2 GHA scaffold was 18.1 ± 0.61 MPa. The values obtained by this scaffold are following the minimum requirements for canceled scaffold so that it can be used as a scaffold candidate in bone tissue engineering.</p>

Effects of Chitosan on Loading and Releasing for Doxorubicin Loaded Porous Hydroxyapatite-Gelatin Composite Microspheres.

Porous hydroxyapatite–gelatin (Hap–Gel) composite microspheres derived by wet chemical methods were used as carriers of doxorubicin (DOX) coupled with chitosan (Chi) for treating cancers. Through X-ray diffraction, specific surface area porosimetry, chemisorption analysis and inductively coupled plasma mass spectrometry, the crystalline phase, composition, morphology, and pore distribution of HAp–Gel microspheres were all characterized. HAp nanosized crystals and Gel polymers form porous microspheres after blending and exhibit a specific surface area of 158.64 m2/g, pore sizes from 3 to 150 nm, and pore volumes of 0.4915 cm3/g. These characteristics are suitable for carriers of DOX. Furthermore, by the addition of chitosan during drug loading, its drug-entrapment efficiency increases from 70% to 99% and the release duration increases from a 100% burst within a day to only 45% over half a year since the pores in the composite microspheres provide a shielding effect throughout the degradation period of the chitosan. According to the MTT tests, cell viability of DOX–Chi/HAp–Gel is 57.64% on day 5, similar to the result treated with DOX only. It is concluded that under the protection of pores in the microspheres, the chitosan abundant of hydroxyls combining HAp–Gel and DOX by forming hydrogen bonds indeed enhances the entrapment efficiency, prolongs the releasing period and maintains DOX’s ability to perform medicine functions unaffected after loading.

Gelatin-hydroxyapatite Fibrous Nanocomposite for Regenerative Dentistry and bone Tissue Engineering

Aims: This study aimed to prepare and physicochemically evaluate as well as assess the cytotoxicity and stimulation of early osteogenic differentiation of dental pulp stem cells of gelatin-hydroxyapatite (Gel-HA) fibrous nanocomposite scaffold. Background: Recently, the electrospinning approach in nanotechnology has been considered due to its application in the preparation of biomimetic nanofibers for tissue engineering. Objective: The main objective of this study was to evaluate Gel-HA fibrous nanocomposite for regenerative dentistry and bone tissue engineering material. Methods: The nano-scaffold was prepared via the electrospinning method. Then, the physicochemical properties (particle size, surface charge, morphology, hydrophilicity, specific surface area, crystalline state and the characterization of functional groups) and the proliferative effects of nano-scaffolds on dental pulp stem cells were assessed. The alkaline phosphatase activity was assessed for evaluation of early osteogenic differentiation of dental pulp stem cells. Results: The prepared nano-scaffolds had a negative surface charge (-30 mv±1.3), mono-dispersed nano-scale diameter (98 nm±1.2), crystalline state and fibrous uniform morphology without any bead (structural defects). The nanofibrous scaffold showed increased hydrophobicity compared to gelatin nanofibers. Based on Brunauer-Emmett-Teller analysis, the specific surface area, pore volume and pore diameter of Gel-HA nanofibers decreased compared to gelatin nanofibers. The Gel-HA nano-fibers showed the proliferative effect and increased the alkaline phosphatase activity of cells significantly (P<0.05). Conclusion: The prepared Gel-HA nanofibers can be considered potential candidates for application in bone tissue engineering and regenerative dentistry. Other: Gel-HA nanofibers could be a potential material for bone regeneration and regenerative dentistry in the near future.

Healing of Artificially Created Gap Non-union Using Autologous Cultured Osteoblasts Impregnated Over Three-Dimensional Biodegradable Scaffold: An Experimental Study (Rabbit).

The large bone defect often require bone transplant or its substitutes to restore bone integrity which have some limitations. The study was conducted to analyze role of autologous osteoblast that are amplified in vivo and impregnated in a synthesized three-dimensional gelatin hydroxyapatite scaffold for treating artificially created critical size defect in rabbit's iliac crest. In this research, 4-month-old ten healthy white male rabbits of average weight 2-3kg were chosen. Osteoblasts cells were isolated from the rabbit iliac crest and were taken in transfer medium to the laboratory and cultured for 2-3weeks. These osteoblast cells were seed on 3-dimensional scaffold and culture the construct for 2weeks. The cultured autologous osteoblasts over the scaffold were transplanted into the defect by reopening the iliac crest of the same rabbit from which is cells were extracted. Serial radiograph of pelvis was done to see progressive signs of union. Out of ten rabbits chosen for study two rabbits were passed during study. Gross and radiological examination of rabbits was done at 0, 4, 8 and 12weeks. Features of union was seen in six rabbits on follow-up. There is no signs of union or minimal new bone formation around the implant material were seen in two case. The study demonstrated using autologous cultured osteoblasts impregnated over three-dimensional biodegradable scaffold for large bone defect is a good option. The importance of three-dimensional biodegradable scaffold is that it provide scaffolding for sufficient interval for new bone formation.

Effect of Temperature on Drug Release: Production of 5-FU-Encapsulated Hydroxyapatite-Gelatin Polymer Composites via Spray Drying and Analysis of In Vitro Kinetics

In this study, 5-fluorouracil- (5-FU-) loaded hydroxyapatite-gelatin (HAp-GEL) polymer composites were produced in the presence of a simulated body fluid (SBF) to investigate the effects of temperature and cross-linking agents on drug release. The composites were produced by wet precipitation at pH 7.4 and temperature 37°C using glutaraldehyde (GA) as the cross-linker. The effects of different amounts of glutaraldehyde on drug release profiles were studied. Encapsulation (drug loading) was performed with 5-FU using a spray drier, and the drug release of 5-FU from the HAp-GEL composites was determined at temperatures of 32°C, 37°C, and 42°C. Different mathematical models were used to obtain the release mechanism of the drug. The morphologies and structures of the composites were analyzed by X-ray diffraction, thermal gravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results demonstrated that for the HAp-GEL composites, the initial burst decreased with increasing GA content at all three studied temperatures. Further, three kinetic models were investigated, and it was determined that all the composites best fit the Higuchi model. It was concluded that the drug-loaded HAp-GEL composites have the potential to be used in drug delivery applications.

Small molecules modified biomimetic gelatin/hydroxyapatite nanofibers constructing an ideal osteogenic microenvironment with significantly enhanced cranial bone formation.

BackgroundRepair of nonunion critical-sized bone defects is a significant clinical challenge all over the world. Construction of osteogenic microenvironment that provides osteoconductive and osteoinductive signals is a leading strategy.Materials and methodsIn the present study, ascorbic acid (AA) and β-glycerophosphate disodium salt hydrate (β-GP) modified biomimetic gelatin/hydroxyapatite (GH) nanofibrous scaffolds were developed by electrospinning. Then the scaffolds were crosslinked by N-hydroxysulfo-succinimide sodium salt (NHS) and 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC). The morphology of the non-crosslinked and crosslinked scaffolds was evaluated by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FT-IR) was used to assess the interacting model between the small molecules and GH scaffold. Then MTT, Alamar Blue, and CCK8 assays were used to investigate the biocompatibility of the various crosslinked scaffolds. Subsequently, the osteogenic genes expression of bone marrow stromal cells (BMSCs) cultured on the scaffolds were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Finally, the crosslinked scaffolds were implanted in a rat calvarial defect model to assess the osteogenic effects in vivo.ResultsSEM results showed that the various scaffolds presented extracellular matrix (ECM)-like fibrous porous structure. (FT-IR) spectrum indicated that AA and β-GP were covalently bonded with GH scaffolds. The MTT, Alamar Blue, and CCK8 assays demonstrated that all the scaffolds can support BMSCs’ growth well. The qRT-PCR results showed that the expression level of Alp and Runx2 in BMSCs on GH/A/B scaffold was about 3.5- and 1.5-fold, respectively, compared with that of GH group on day 7. The results also showed that AA- and β-GP-modified GH scaffolds can significantly induce the higher levels of osteogenic gene expression in a temporal specific manner. Importantly, AA and β-GP synergistically promoted osteoblast differentiation in vitro and dramatically induced bone regeneration in vivo. Impressively, AA and β-GP dual modified GH nanofibrous scaffold could serve as a template for guiding bone regeneration and the bone defects were almost repaired completely (94.28%±5.00%) at 6 weeks. Besides, single AA or β-GP-modified GH nanofibrous scaffolds could repair 62.95%±9.39% and 66.56%±18.45% bone defects, respectively, at 12 weeks in vivo. In addition, AA and β-GP exhibit an anti-inflammatory effect in vivo.ConclusionOur data highlighted that, AA, β-GP, and GH nanofibers created a fine osteoconductive and osteoinductive microenvironments for bone regeneration. We demonstrated that AA and β-GP dual modified GH nanofiber is a versatile bone tissue engineering scaffold.

Bioinspired Modification of Poly(L-lactic acid)/Nano-Sized β-Tricalcium Phosphate Composites with Gelatin/Hydroxyapatite Coating for Enhanced Osteointegration and Osteogenesis.

Compared to pure poly(L-lactic acid) (PLLA), PLLA/nano-sized β-tricalcium phosphate (PLLA/nβ-TCP) composites show both superior interfacial compatibility and osteoinductive, and consequently hold great potential for bone defect repair applications. However, their dismal osteointegration limits their further development in bone regeneration, adding the need for tailored modification. In this study, a bioinspired modification approach was proposed to construct gelatinhydroxyapatite (GEL/HAP) coating onto PLLA/nβ-TCP composites by combining chemical grafting with in situ reaction methods. The incorporation of the biomimetic GEL/HAP coating substantially improved MC3T3-E1 cell adhesion, proliferation and osteogenic differentiation, as demonstrated by morphological observation. Cell Counting Kit-8 (CCK-8) assay, alkaline phosphate activity test (ALP), and quantitative real-time polymerase chain reaction (qRT-PCR) analysis. Furthermore, GEL/HAP-PLLA/nβ-TCP composites and their control counterparts (i.e., bare PLLA/nβ-TCP) were synchronously implanted into femoral condylar defects of an identical rabbit. Characterizations including microcomputed tomography (micro-CT), histological analysis and the push-out test revealed that the biomimetic coating not only improved osteointegration but also significantly promoted bone regeneration. Overall, for the first time, bioinspired surface modification of the PLLA/nβ-TCP composite with GEL/HAP coating was demonstrated to be an efficient strategy for enhancing the osteointegration and osteogenesis functions of bone implants.

Dramatic Improvement of the Mechanical Strength of Silane-Modified Hydroxyapatite-Gelatin Composites via Processing with Cosolvent.

Bone tissue engineering (BTE) requires a sturdy biomaterial for scaffolds for restoration of large bone defects. Ideally, the scaffold should have a mechanical strength comparable to the natural bone in the implanted site. We show that adding cosolvent during the processing of our previously developed composite of hydroxyapatite–gelatin with a silane cross-linker can significantly affect its mechanical strength. When processed with tetrahydrofuran (THF) as the cosolvent, the new hydroxyapatite–gelatin composite can demonstrate almost twice the compressive strength (97 vs 195 MPa) and biaxial flexural strength (222 vs 431 MPa) of the previously developed hydroxyapatite–gelatin composite (i.e., processed without THF), respectively. We further confirm that this mechanical strength improvement is due to the improved morphology of both the enTMOS network and the composite. Furthermore, the addition of cosolvents does not appear to negatively impact the cell viability. Finally, the porous scaffold can be easily fabricated, and its compressive strength is around 11 MPa under dry conditions. All these results indicate that this new hydroxyapatite–gelatin composite is a promising material for BTE application.

Improved cell adhesion and osteogenesis using a PLTGA (poly l-lactide, 1,3-trimethylene carbonate, and glycolide) terpolymer by gelatin-assisted hydroxyapatite immobilization for bone regeneration.

A PLTGA (poly l-lactide, trimethylene carbonate, glycolide) terpolymer possesses great potential for orthopedic applications due to its excellent biocompatibility and controllable biodegradability. However, the unfavorable surface conditions of bare PLTGA such as its poor hydrophilicity and smooth morphology impede its clinical applications, highlighting the need for tailored surface modifications to improve its cytological behavior and osteogenic capacity. We herein develop a facile and effective strategy to deposit a gelatin/hydroxyapatite (GEL/HAP) hybrid coating onto the surface of PLTGA that involves consecutive chemical grafting and in situ reaction steps. Following the surface modification treatment, the resultant PLTGA scaffold with the GEL/HAP coating exhibited drastically improved hydrophilicity (79.1°vs. 48.2° in water contact angle) and increased surface roughness (18.4 vs. 267.9 nm, more than 14-fold, in root-mean-square roughness), respectively. In addition, preosteoblast (MC3T3-E1) cells were seeded onto the bare/modified PLTGA scaffold to evaluate biological performance, including cell adhesion, proliferation, mineralization and osteogenic differentiation. Based on these results, the GEL/HAP hybrid coating can endow the PLTGA terpolymer substrate with enhanced cell adhesion, proliferation and osteogenic functionality. Overall, post-treatment of PLTGA with the GEL/HAP hybrid coating may be a promising methodology in bone regeneration applications.

Synthesis and characterization of mechanically strong carboxymethyl cellulose–gelatin–hydroxyapatite nanocomposite for load-bearing orthopedic application

Novel three-dimensional hybrid polymer–hydroxyapatite nanocomposites have been developed as load-bearing synthetic bone graft through in situ mineralization process, using natural polymers carboxymethyl cellulose (CMC) and gelatin (Gel) as matrix. This process is simple and does not involve any chemical cross-linker. Detailed structural and physicochemical characterization of the samples disclosed that incorporation of gelatin with CMC assists the formation of CMC-Gel polymeric network of new conformational structure through non-covalent interactions (H-bond). The formation of hydroxyapatite (HA) in this polymeric network was occurred in such a fashion that the HA serves as bridging molecule which strengthen the polymeric network more and formed a mechanically strong three-dimensional CMC-Gel-HA nanocomposite. The synthesized CMC-Gel-HA nanocomposites have compressive strength and modulus in the range of 40–86 MPa and 0.4–1.2 GPa, respectively, analogous to human cancellous as well as cortical bone. In vitro cell interaction of the synthesized nanocomposites with osteoblast-like MG-63 cells has been evaluated. Results showed that synthesized CMC-Gel-HA nanocomposite promote cells for high alkaline phosphatase activity and extracellular mineralization. Extracellular mineralization ability of nanocomposite was investigated by alizarin red staining and von Kossa staining. Biodegradable nature and bone apatite formation ability of CMC-Gel-HA nanocomposite under simulated physiological environment were investigated by different characterization processes. Results indicated that the synthesized CMC-Gel-HA nanocomposite has great potential to be used as regenerative bone graft in major load-bearing region.

Calcite and Hydroxyapatite Gelatin Composites as Bone Substitution Material Made by the Double Migration Technique

The double migration technique, which is based on mineral formation in an electrical field, was used to synthesize composites of gelatin with calcium phosphate and carbonate, respectively, in order to generate a degradable bone substitute material. Gelatin is integrated in the mineralization process to increase the minerals solubility, in analogy to the formation of the bone mineral dahllite. The mineral formation is affected with respect to the particle size, shown by transmission electron microscopy. Machined polyacrylic barriers increased gelatin stability and allowed investigation of the influence of gelatin barrier position and ion concentrations within the mineralization solutions on mineral morphology and structure by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. During degradation of the mineral in simulated body fluid, the possibility of an adjustable calcium ion concentration could be shown, which might be useful to manipulate the osteoblast/osteoc...

A new approach to produce calcium-phosphate coatings on titanium

In the study, hydroxyapatite-gelatin composite powders were synthesized from simulated body fluid (SBF) with gelatin content ranging from 1 to 3 wt. %. It was established that all the samples were single-phase and represented hydroxyapatite. The surface and morphological characteristics of the produced hydroxyapatite-gelatin (HAG) based coatings were studied. Uniform deposition of the composite on the titanium substrate surface (VT1-0) was found to occur on etched titanium samples. It is shown that exposure of titanium substrates with hydroxyapatite-gelatin (HAG) based coating to powerful ion beam can stimulate further growth of crystals and regeneration of the surface.

Dopaminergic enhancement of cellular adhesion in bone marrow derived mesenchymal stem cells (MSCs).

Dopamine (DA) is a well-known neurotransmitter and critical element in the mussel adhesive protein that has gained increasing attention for its role in cellular growth enhancement in biomaterials, including cellular adhesion improvement. As the mechanism underlying this remains unclear, the objective of this study was to explore the effects of DA on the adhesion properties of bone marrow derived rat mesenchymal stem cells (rMSCs) using an hydroxyapatite gelatin nanocomposite biomaterial and to test whether the effects are mediated through various endogenously expressed DA receptors. Primary rMSCs were pretreated with D1-like antagonist, D2-like antagonist, or a combination of these antagonists followed by treatment with 50 μM DA and cellular adhesion quantification at 0.5, 1, 2 and 4 hours post DA addition. DA was found to increase rMSC adhesion and spreading at the 0.5 hour time-point and the dopaminergic effect on cell adhesion was partially blocked by DA antagonists. In addition, the D1-like and D2-like antagonists appeared to have a similar effect on rMSCs. Immunofluorescent staining indicated that the rMSC spreading area was significantly increased in the DA treated group versus the control group. Treatment of the D1-like DA antagonists with DA revealed that the actin filaments of rMSCs could not connect the membrane with the nucleus. In summary, DA was found to enhance early rMSC adhesion partially via DA receptor activation.

Repair of rat critical size calvarial defect using osteoblast-like and umbilical vein endothelial cells seeded in gelatin/hydroxyapatite scaffolds.

The present study used a previously developed three-dimensional Gelatin/Hydroxyapatite (Gel/HA) homogeneous nanocomposite scaffold with porosity of 82% and interconnecting pores ranging from 300 to 500 μm. Cell-seeded scaffolds were used to evaluate bone regeneration of rat critical-size calvarial defect. Totally, 36 male Wistar rats were randomly divided into four experimental groups, including blank defect (defects without any graft), blank scaffold (defects filled with Gel/HA scaffold without cells), and two groups of cell-seeded scaffolds (defects filled with either Gel/HA scaffold seeded with osteoblast-like and endothelial cells or osteoblast-like cell-seeded constructs). After 1, 4, and 12 weeks of scaffold implantation, rats were sacrificed and the calvaria were harvested for histological, immunohistochemical and histomorphometric analysis. In vitro tests showed that scaffolds were nontoxic to cells and promoted ideal cellular attachment. In vivo investigation on scaffold revealed that blank calvarial defects indicated incomplete tissue coverage and little evidence of bone healing. However, blank scaffold and cell-seeded scaffolds significantly promoted osteoconduction and ostegogenesis. Taken together, pre-seeded Gel/HA nanocomposite scaffold with osteoblasts and endothelial cells presented an effective combination to improve osteogenesis in the engineered bone implant. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1770-1778, 2016.

Development of simvastatin contained gelatin hydroxyapatite spherodized granules with controlled drug release

Development of simvastatin contained gelatin hydroxyapatite spherodized granules with controlled drug release

CFD modelling of a mixing chamber for the realisation of functionally graded scaffolds

Biological tissues are characterised by spatially distributed gradients, intricately linked with functions. It is widely accepted that ideal tissue engineered scaffolds should exhibit similar functional gradients to promote successful tissue regeneration. Focusing on bone, in previous work we proposed simple methods to obtain osteochondral functionally graded scaffolds (FGSs), starting from homogeneous suspensions of hydroxyapatite (HA) particles in gelatin solutions. With the main aim of developing an automated device to fabricate FGSs, this work is focused on designing a stirred tank to obtain homogeneous HA–gelatin suspensions. The HA particles transport within the gelatin solution was investigated through computational fluid dynamics (CFD) modelling. First, the steady-state flow field was solved for the continuous phase only. Then, it was used as a starting point for solving the multi-phase transient simulation. CFD results showed that the proposed tank geometry and setup allow for obtaining a homogeneous suspension of HA micro-particles within the gelatin solution.

Preparation and characterization of gelatin/hydroxyapatite nanocomposite for bone tissue engineering

Homogeneous gelatin/hydroxyapatite (GEL/HA) nano-composites were synthesized by a novel in situ precipitation method, and its corresponding characterizations, including composition, morphology, pore structure, thermal stability, mechanical strength, and biocompatibility, were carried out. High-magnified scanning electron microscope (SEM) images indicated that nano-HA with particle size ranging from 20 to 50 nm were uniformly distributed in GEL matrix and tightly integrated with organic phase. Wide angle X-ray diffraction (XRD) analysis and transmission electron microscope (TEM) images showed that, during the process of mineralization, there existed preferred oriented growth of HA crystals along (002) and (211) crystal planes. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) indicated that, the thermal stability of GEL molecules enhanced by hybridizing with HA nanocrystals. Interconnected porous GEL/HA nanocomposites with pore size ranging between 50 and 350 μm were prepared by a freeze-drying method. This pore size was adequate for bone tissue engineering (BTE) applications. In addition, in vitro MG63 osteoblast-like cell culture illuminated that GEL/HA nanocomposites had excellent cytocompatibility and could promote proliferation of cells. These results suggested that GEL/HA nanocomposite might be an ideal bone substitute. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Preparation and characterization of gelatin-hydroxyapatite composite microspheres for hard tissue repair.

Gelatin-hydroxyapatite composite microspheres composed of 21% gelatin (G) and 79% hydroxyapatite (HA) with uniform morphology and controllable size were synthesized from a mixed solution of Ca(NO3)2, NH4H2PO4 and gelatin by a wet-chemical method. Material analyses such as X-ray diffraction (XRD), scanning/transmission electron microscopy examination (SEM/TEM) and inductively coupled plasma-mass spectroscopy (ICP-MS) were used to characterize G-HA microspheres by analyzing their crystalline phase, microstructure, morphology and composition. HA crystals precipitate along G fibers to form nano-rods with diameters of 6-10nm and tangle into porous microspheres after blending. The cell culture indicates that G-HA composite microspheres without any toxicity could enhance the proliferation and differentiation of osteoblast-like cells. In a rat calvarial defect model, G-HA bioactive scaffolds were compared with fibrin glue (F) and Osteoset® Bone Graft Substitute (OS) for their capacity of regenerating bone. Four weeks post-implantation, new bone, mineralization, and expanded blood vessel area were found in G-HA scaffolds, indicating greater osteoconductivity and bioactivity than F and OS.