Enhanced bone regeneration usingAntheraea mylittasilk fibroin and chitosan based scaffold:in-vivoandin-vitrostudy.

In this study, highly interconnected porous scaffolds fromAntheraea mylittasilk fibroin (SF) and chitosan (CH) were fabricated using the freeze-drying method. The weight ratios of SF to CH were varied from 90:10 (SF90/CH10) to 50:50 (SF50/CH50) to prepare the scaffolds from the aqueous suspension of the protein-polysaccharide mix. From the initial optimization of scaffold composition with respect to their microstructure, porosity, and mechanical properties, the SF80/CH20scaffold exhibited the most suitable properties for bone tissue engineering application as compared to others compositions. Hencein-vitrohemocompatibility, protein adsorption, and MG-63 cell culture studies were carried out for SF80/CH20scaffold. The fabricated SF80/CH20scaffold showed a more controlled swelling percentage of 42.8%, with high BSA protein adsorption of 0.39 mg of BSA per gm of the scaffold at 24 h incubation period. Furthermore,in-vitroMG-63 cell culture study onto the fabricated SF80/CH20scaffold elicited excellent MG-63 cell attachment with better biocompatibility and cell viability with increased F-action production from day 3 to day 7 of the cell culture period.In vivobone defect healing in a rabbit tibia model revealed excellent bone healing capacity in SF80/CH20scaffold implanted specimens compared to control ones, as evident from histology and fluorochrome labeling analysis.

Preparation, characterization, and bioactivity of reinforced monetite with chitosan-gelatin electrospun composite scaffold for bone tissue engineering.

In this study, chitosan-gelatin-monetite (CGM)-based electrospun scaffolds have been developed that closely mimicked the microstructure and chemical composition of the extracellular matrix of natural bone. CGM-based nanofibrous composite scaffolds were prepared with the help of the electrospinning technique, post-cross-linked using ethyl(dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide solution to improve their stability in an aqueous environment. The prepared chitosan/gelatin (CG) scaffold showed an average fiber diameter of 308 ± 17 nm, whereas 5 and 7 wt% monetite containing CGM5and CGM7scaffolds, exhibited an average fiber diameter of 287 ± 13 and 265 ± 9 nm, respectively, revealing the fine distribution of monetite particles on the fibrous surface. The distribution of monetite nanoparticles onto the CG nanofibrous surface was confirmed using x-ray diffraction, Fourier transform infrared, and EDAX. Moreover, the addition of 7 wt% monetite into the CG electrospun matrix increased their ultimate tensile strength from 7.62 ± 0.13 MPa in the CG scaffold to 14.34 ± 0.39 MPa in the CGM7scaffold. Simulated body fluid study and staining with alizarin red S (ARS) confirmed the higher mineralization ability of monetite-containing scaffolds compared to that revealed by the CG scaffold. The monetite incorporation into the CG matrix improved its osteogenic properties, including pre-osteoblast MG-63 cell adhesion, proliferation, and differentiation, when seeded with the cells. A higher degree of cellular adhesion, spreading, and migration was observed on the monetite-incorporated CG scaffold than that on the CG scaffold. From 3-(4, 5-dimethylthiazol-2-yl-2, 5-diphenyltetrazolium bromide) MTT assay, alkaline phosphatase activity, ARS staining, and immunocytochemistry study, the cultured cells discovered a more conducive microenvironment to proliferate and subsequently differentiate into osteoblast lineage in contact with CGM7nanofibers rather than that in CGM0and CGM5.In-vitroresults indicated that electrospun CGM-based composite scaffolds could be used as a potential candidate to repair and regenerate new bone tissues.

Physicochemical, mechanical, dielectric, and biological properties of sintered hydroxyapatite/barium titanate nanocomposites for bone regeneration.

Bone implants fabricated using nanocomposites containing hydroxyapatite (HA) and barium titanate (BT) show osteoconductive, osteoinductive, osteointegration, and piezoelectricity properties for bone regeneration applications. In our present study, HA and BT nanopowders were synthesized using high-energy ball-milling-assisted solid-state reaction with precursors of calcium carbonate and ammonium dihydrogen phosphate, and barium carbonate and titanium oxide powder mixtures, respectively. Hexagonal HA and tetragonal BT phases were formed after calcination at 700 and 1000 °C, respectively. Subsequently, hydroxyapatite/barium titanate (HA/BT) nanocomposites with different weight percentages of HA and BT were prepared by ball-milling, then compacted and sintered at two different temperatures to endow these bioceramics with better mechanical, dielectric, and biological properties for bone regeneration. Microstructure, crystal phases, and molecular structure characterizations of these sintered HA/BT nanocomposite compacts (SHBNCs) were performed using field-emission scanning electron microscopy, x-ray diffraction, and Fourier-transform infrared spectroscopy, respectively. Bulk density was evaluated using the Archimedes method. HA/BT nanocomposites with increased BT content showed enhanced dielectric properties, and the dielectric constant (ϵr) value for 5HA/95BT was ∼182 at 100 Hz. Mechanical properties such as Vicker's hardness, fracture toughness, yield strength, and diametral tensile strength were also investigated. The hemolysis assay of SHBNCs exhibited hemocompatibility. The effect of these SHBNCs as implants on thein vitrocytocompatibility and cell viability of MG-63 osteoblast-like cells was assessed by MTT assay and live/dead staining, respectively. 15HA/85BT showed increased metabolic activity with a higher number of live cells than BT after the culture period. Overall, the SHBNCs can be used as orthopedic implants for bone regeneration applications.

Gelatin/monetite electrospun scaffolds to regenerate bone tissue: Fabrication, characterization, and in-vitro evaluation.

This work is dedicated to combining nanotechnology with bone tissue engineering to prepare and characterize electrospun gelatin/monetite nanofibrous scaffold with improved physicochemical, mechanical, and biological properties. Nanofibrous scaffolds possessing fiber diameter in the range of 242-290 nm were prepared after incorporating varying content of monetite nanoparticles up to 7 wt % into the gelatin matrix using the electrospinning technique. Cross-linking of gelatin chains in the scaffold was performed using 0.25 wt% glutaraldehyde as indicated by imine (-CN-) bond formation in the FTIR analysis. With an increase in monetite addition up to 7 wt%, a decrease in swelling ratio and bio-degradability of cross-linked gelatin scaffolds was observed. Gelatin scaffold with 7 wt% monetite content registered the highest values of tensile strength and tensile modulus of 18.8 MPa and 170 MPa, as compared to 0% and 5 wt% monetite containing scaffolds respectively. Cell viability and differentiation were studied after culturing MG-63 cells onto the scaffolds from confocal microscopy of live and dead cells images, MTT assay, and alkaline phosphatase assay for a cell culture period of up to 21 days. It was observed that 7 wt % monetite containing gelatin scaffold exhibited better MG-63 cell adhesion, proliferation, higher biomineralization, and ALP activity compared to 0% and 5 wt% monetite containing electrospun scaffolds studied here.

Gelatin-based electrospun and lyophilized scaffolds with nano scale feature for bone tissue engineering application: review.

The rebuilding of the normal functioning of the damaged human body bone tissue is one of the main objectives of bone tissue engineering (BTE). Fabricated scaffolds are mostly treated as artificial supports and as materials for regeneration of neo bone tissues and must closely biomimetic the native extracellular matrix of bone. The materials used for developing scaffolds should be biodegradable, nontoxic, and biocompatible. For the resurrection of bone disorder, specifically natural and synthetic polymers such as chitosan, PCL, gelatin, PGA, PLA, PLGA, etc. meet the requirements for serving their functions as artificial bone substitute materials. Gelatin is one of the potential candidates which could be blended with other polymers or composites to improve its physicochemical, mechanical, and biological performances as a bone graft. Scaffolds are produced by several methods including electrospinning, self-assembly, freeze-drying, phase separation, fiber drawing, template synthesis, etc. Among them, freeze-drying and electrospinning are among the popular, simplest, versatile, and cost-effective techniques. The design and preparation of freeze-dried and electrospun scaffolds are of intense research over the last two decades. Freeze-dried and electrospun scaffolds offer a distinctive architecture at the micro to nano range with desired porosity and pore interconnectivity for selective movement of small biomolecules and play its role as an appropriate matrix very similar to the natural bone extracellular matrix. This review focuses on the properties and functionalization of gelatin-based polymer and its composite in the form of bone scaffolds fabricated primarily using lyophilization and electrospinning technique and their applications in BTE.

Macro-to-micro porous special bioactive glass and ceftriaxone-sulbactam composite drug delivery system for treatment of chronic osteomyelitis: an investigation through in vitro and in vivo animal trial.

A systematic and extensive approach incorporating in vitro and in vivo experimentation to treat chronic osteomyelitis in animal model were made using antibiotic loaded special bioactive glass porous scaffolds. After thorough characterization for porosity, distribution, surface charge, a novel drug composite were infiltrated by using vacuum infiltration and freeze-drying method which was subsequently analyzed by SEM-EDAX and studied for in vitro drug elution in PBS and SBF. Osteomyelitis in rabbit was induced by inoculation of Staphylococcus aureus and optimum drug-scaffold were checked for its efficacy over control and parenteral treated animals in terms of histopathology, radiology, in vivo drug concentration in bone and serum and implant-bone interface by SEM. It was optimized that 60P samples with 60-65% porosity (bimodal distribution of macro- to micropore) with average pore size ~60 µm and higher interconnectivity, moderately high antibiotic adsorption efficiency (~49%) was ideal. Results after 42 days showed antibiotic released higher than MIC against S. aureus compared to parenteral treatment (2 injections a day for 6 weeks). In vivo drug pharmacokinetics and SEM on bone-defect interface proved superiority of CFS loaded porous bioactive glass implants over parenteral group based on infection eradication and new bone formation.

Monetite addition into gelatin based freeze-dried scaffolds for improved mechanical and osteogenic properties.

This study was aimed at fabricating monetite nanoparticles impregnated gelatin-based composite scaffold to improve the chemical, mechanical and osteogenic properties. Scaffolds were fabricated using a freeze-drying technique of the slurry containing a varying proportion of gelatin and monetite. The lyophilized scaffolds were cross-linked with 0.25 wt% glutaraldehyde solution to obtain a three-dimensional (3D) interconnected porous microstructure with improved mechanical strength and stability in a physiological environment. The fabricated scaffolds possessed >80% porosity having 3D interconnected pore size distribution varying between 65 and 270 µm as evident from field emission scanning electron microscopy analysis. The average pore size of the prepared scaffold decreased with monetite addition as reflected in values of 210 µm for pure gelatin GM0scaffold and 118 µm registered by GM20scaffold. On increase in monetite content up to 20 wt% of total polymer concentration, compressive strength of the prepared scaffolds was increased from 0.92 MPa in pure gelatin-based GM0to 2.43 MPa in GM20. Up to 20 wt% of monetite reinforced composite scaffolds exhibited higher bioactivity as compared to that observed in pure gelatin-based GM0scaffold. Simulated body fluid (SBF) study and alizarin red assays confirmed higher bio-mineralization ability of GM20as compared to that exhibited by GM0. Human preosteoblast cells (MG-63) revealed higher degree of filopodia and lamellipodia extensions and excellent spreading behavior to anchor with GM20matrix as compared to that onto GM0and GM10. MTT assay and alkaline phosphatase staining study indicated that MG-63 cells found a more conducive environment to proliferate and subsequently differentiate into osteoblast lineage when exposed to GM20scaffolds rather than to GM0and GM10. This study revealed that up to 20 wt% monetite addition in gelatin could improve the performance of prepared scaffolds and serve as an efficient candidate to repair and regenerate bone tissues at musculoskeletal defect sites.

Hydroxyapatite-collagen nanoparticles reinforced polyanhydride based injectable paste for bone substitution: effect of dopant addition in vitro.

The present study focuses on the synthesis and characterization of hydroxyapatite-collagen nanoparticles incorporated polyanhydride paste and investigating its bone regeneration capacity in vitro. Photocrosslinkable polyanhydride paste was prepared after synthesizing methacrylate derivatives of 1,6-bis(p-carboxyphenoxy)hexane (MCPH) and sebacic acid dimethacrylate (MSA). These multifunctional monomers, namely 45 wt% MSA, 45 wt% MCPH in addition to 10 wt% poly(ethylene glycol)diacrylate (PEGDA) were photopolymerized under ultraviolet light (365 nm) to produce highly crosslinked polyanhydride networks using camphroquinone (CQ)/ethyl 4-(dimethylamino)benzoate [4-EDMAB] for light initiated crosslinking and benzoyl peroxide (BPO)/dimethyl toludine (DMT) for chemically initiated crosslinking. Separately, using the co-precipitation process, (1 wt%) Si, (1 wt%) Sr, and (0.5 + 0.5) wt% Si/Sr was doped into hydroxyapatite-collagen nanoparticles in size range between 50 and 70 nm. Si, Sr, and both Si/Sr doped hydroxyapatite-collagen nanoparticles to the extent 10 wt% were added to polyanhydride monomer mixture containing 40 wt% MSA, 40 wt% MCPH and 10 wt% PEGDA and subsequently photopolymerized as previously mentioned. Incorporation of hydroxyapatite-collagen nanoparticles to the extent of 10 wt% into polyanhydride matrix enhanced compressive strength of the hardened paste from 30 to 49 MPa. Mesenchymal stem cells obtained from the human umbilical cord were cultured onto pure polyanhydride and hydroxyapatite-collagen added scaffold to assess their cellular proliferation and differentiation capacity to bone cell. MTT assay showed that mesenchymal stem cell proliferation was significantly higher in Si/Sr binary doped hydroxyapatite-collagen-polyanhydride sample as compared to other samples. Again from immunocytochemistry study using confocal images suggested that expression of osteocalcin, a marker indicating differentiation into osteoblast, was the highest in Si/Sr binary doped hydroxyapatite-collagen-polyanhydride sample against the other samples studied in this case. This study thus summarizes the development of photocurable biocomposites containing polyanhydride and Si, Sr doped hydroxyapatite-collagen nanoparticles that exhibited tremendous promise to regenerate bone tissues in complex-shaped musculoskeletal defect sites.

Mechanical, Electrical, and Biological Properties of Mechanochemically Processed Hydroxyapatite Ceramics.

The effect of the sintering temperature on densification and the resultant mechanical, electrical, and biological properties of mechanochemically processed hydroxyapatite (HAp) samples was investigated. HAp samples were sintered at 1200, 1250, and 1300 °C for 4 h, respectively. HAp samples sintered at 1250 °C showed better mechanical properties, which was attributed to their smaller grain size compared to HAp samples at higher sintering temperatures. The nearly identical value of the dielectric constant (εr) and better cell proliferation was exhibited by HAp samples sintered at 1250 and 1300 °C, respectively. At ~210 °C, in all the samples sintered at different temperatures, a dielectric anomaly was obtained, which was attributed to the phase transition temperature of the HAp system. Dielectric properties near the phase transition temperature showed a dielectric relaxation-type of behavior, which was attributed to the re-orientational motion of OH- ions in the HAp system. Higher cell proliferation and viability were exhibited by the HAp1300 samples, whereas comparatively equivalent cell growth and higher mechanical strength were observed in the HAp1250 samples.

Zn- and Mg-doped hydroxyapatite nanoparticles for controlled release of protein.

Bovine serum albumin (BSA) protein incorporated with hydroxyapatite (HA) nanoparticles (NPs) were synthesized by an in situ precipitation process. 2 mol % Zn(2+) and Mg(2+) were used as dopants to synthesize Zn(2+)/Mg(2+)-doped HA-BSA NPs. In our study we used BSA as a model protein. The amount of BSA uptake by doped and undoped HA NPs and subsequent release of BSA from NPs were investigated. Zn-doped HA NPs showed the highest amount of BSA uptake, whereas the amount of BSA loaded in undoped HA NPs was the lowest. A two-stage BSA release profile from doped and undoped HA NPs was observed in phosphate buffer solution (PBS) at pH 7.2 +/- 0.2. The initial burst release was due to the desorption of BSA from the HA surface. The later stage of slow release was controlled by the dissolution of BSA incorporated HA NPs. The BSA release rate from Zn-doped HA NPs was found to be the highest, whereas undoped HA NPs released BSA at the slowest rate. Our study showed that the protein release rate from HA NPs can be controlled by the addition of suitable dopants, and doped HA-based NP systems can be used in bone growth factor and drug release study.

Photo-crosslinked alginate nano-hydroxyapatite paste for bone tissue engineering.

In this study, methacrylation of alginate was carried out by reacting sodium alginate with methacrylic anhydride in the presence of sodium hydroxide. Separately synthesized nano-hydroxyapatite (nano-HAp) powder was surface functionalized using mercaptopropionic acid and ethylene glycol methacrylate phosphate (EGMP) in the presence of azobisisobutyronitrile benzene as a free radical initiator in a nitrogen atmosphere. Methacrylated alginate solution was mixed with the required amount of surface-functionalized HAp nanoparticles in the presence of 0.05% Irgacure 2959 as a photoinitiator and was placed at the centre of a 8 kW UV light source (265 nm) to prepare photo-crosslinked bone paste. X-ray diffraction analysis indicated that surface functionalization did not alter phase purity of HAp nanopowder in the prepared paste. The graft polymerization of EGMP on the surface of HAp was confirmed by the presence of the 1732 cm-1 band, which belongs to C=-O stretching of EGMP, in addition to the characteristic peaks of nano-HAp and alginate in the composite paste. The storage and loss moduli of all the prepared pastes increased non-linearly with time up to 100 s, demonstrating their pseudo plastic behaviour. The rate of release of bone morphogenetic protein 2 (BMP-2) was significantly faster in the first few days, and the release curve gradually levelled off prior to slowing down up to 22 d. Mesenchymal stem cell adhesion studies revealed that cells could attach to the paste material and stretch over the surface of the material after 14 d of incubation. MTT assay showed that prepared paste materials were conducive to attachment and proliferation of mesenchymal stem cells. Immunocytochemical analysis revealed that the addition of surface-functionalized nano-HAp and BMP-2 to alginate hydrogel enhanced the osteogenic potential of the prepared paste. The results indicate that the newly developed photo-crosslinked paste may be physically and biologically suitable for application as a bone filler.

Optimization of electrospinning process & parameters for producing defect-free chitosan/polyethylene oxide nanofibers for bone tissue engineering.

Chitosan (CS) nanofibers were electrospun from aqueous chitosan solution using concentrated acetic acid solution as a solvent. Polyethylene oxide (PEO) with varying weight content from 10- 60 wt% was mixed with chitosan solution that acted as a plasticizer to improve spinability of the prepared chitosan solution. With the increase in PEO content from 10-50 wt% the viscosity of the resultant CS/PEO solution was decreased from 0.938 Pa-s to 0.272 Pa-s, whereas higher the concentration of acetic acid lower was the surface tension of resultant chitosan solution. It was found beadless nanofibrous chitosan mat was obtained not less than 85% acetic acid concentration, 50 wt% PEO and at 0.2 wt% NaCl and 5 wt% total polymer concentration. From field emission scanning electron microscopy (FESEM) investigation, it was observed that chitosan fibers with an average diameter of 149 nm were produced at an applied voltage of 22.5 KV, while that varied between 17.5- 25 KV. On the other hand, a minimum of 110 nm of average diameter chitosan nanofiber was obtained at a needle tip to rotor collector distance of 15 cm by the method of electrospining. In terms of solution flow rate, 0.4 mL/h was found to be optimum in obtaining defect-free electrospun fiber with lower average diameter. As a whole, smooth and uniform chitosan nanofibers were obtained from 50/50 CS/PEO solution prepared by using 90% acetic acid and electrospun at 20 kV applied voltage, 15 cm needle tip-to- rotor collector distance with 0.2 mm inner diameter needle and 0.4 mL/h feeding rate. After crosslinking with 1 wt% glutaraldehyde (GTA), the ultimate tensile strength and Young's modulus of chitosan scaffold increased upto 9.47 MPa and 147.75 MPa respectively. From MTT assay and alkaline phosphatase expression analysis upto 11 days of cell culture period it was evident that thus prepared electrospun CS scaffolds supported MG 63 cell proliferation and its differentiation into mature osteoblast.

Preparation, characterization and bioactivities of nano anhydrous calcium phosphate added gelatin-chitosan scaffolds for bone tissue engineering.

Gelatin, chitosan and nano calcium phosphate based composite scaffold with tailored architectures and properties has great potential for bone regeneration. Herein, we aimed to improve the physico chemical, mechanical and osteogenic properties of 3D porous scaffold by incorporation of dihydrogen calcium phosphate anhydrous (DCPA) nanoparticles into biopolymer matrix with variation in composition in the prepared scaffolds. Scaffolds were prepared from the slurry containing gelatin, chitosan and synthesized nano DCPA particle using lyophilization technique. DCPA nano particles were synthesized using calcium carbonate and phosphoric acid in water-ethanol medium. XRD pattern showed phase pure DCPA in synthesized nanopowder. Scaffolds were prepared by addition of DCPA nanoparticles to the extent of 5-10 wt% of total polymer into gelatin-chitosan solution with solid loading varying between 2.5 and 2.75 wt%. The prepared scaffold showed interconnected porosity with pore size varying between 110 and 200 micrometer. With addition of DCPA nanoparticles, average pore size of the prepared scaffolds decreased. With increase in nano ceramic phase content from 5 wt% to 10 wt% of total polymer, the compressive strength of the scaffold increased. Scaffold containing 10 wt% DCPA showed the highest average compressive strength of 2.2 MPa. Higher cellular activities were observed in DCPA containing scaffolds as compared to pure gelatin chitosan scaffold suggesting the fact that nano DCPA addition into the scaffold promoted better osteoblast adhesion and proliferation as evident from MTT assay and scanning electron microscopic (SEM) investigation of osteoblast cultured scaffolds. A higher degree of lamellopodia and filopodia extensions and better spreading behavior of osteoblasts were observed in FESEM micrographs of MG 63 cultured DCPA containing scaffold. The results demonstrated that both mechanical strength and osteogenic properties of gelatin-chitosan scaffold could be improved by addition of anhydrous dihydrogen calcium phosphate nanoparticles into it.

Investigating the mechanical, physiochemical and osteogenic properties in gelatin-chitosan-bioactive nanoceramic composite scaffolds for bone tissue regeneration: In vitro and in vivo.

The aim of this work was to compare the efficacy of gelatin-chitosan based bone scaffolds after incorporation of three different bioactive nanoparticles such as hydroxyapatite (HAp), ß­tricalcium phosphate (ß-TCP) and 58s bio active glass by evaluating its physicochemical, mechanical and osteogenic properties. Gelatin-chitosan based scaffolds made of gelatin-chitosan (GC) and GC composites containing 30 wt% HAp, ß-TCP and 58s bioactive glass nanoparticles were fabricated using freeze drying technique. The porosity and compressive strength of all the prepared scaffolds were evaluated. The average pore size of all the prepared composite scaffolds was in the range between 90 and 125 µm. Most frequent pore size in GCT 30 scaffold was the highest of 120 µm whereas that for GCH 30 was the lowest of 96 µm as suggested by Hg porosimetry analysis. GCH30 scaffolds showed the highest average compressive strength of 3.45 MPa as opposed to 2.24 MPa exhibited by GCB 30, with high degree of interconnected porosity appropriate for cellular colonization. To study the effect of different bioceramic phases on MSCs differentiation, scaffolds were cell cultured for up to 14 days in osteogenic medium. GCB30 scaffold showed higher capacity to proliferate MSCs cultured onto it as compared to other composite scaffolds. Degree of differentiation of MSCs into osteoblast was higher in GCB30 scaffolds than in the GCH30 and GCT30 composite scaffold as evident from higher amount of RUNX2 and osteocalcin expression in the former up to 14 days of cell culture. Inclusion of 58s bioactive glass particles showed positive effects on cell differentiation. In coherence with the in vitro appearance, histomorphometric analysis and fluorochrome study in a rabbit tibia model showed a significantly greater amount of new bone formation in GCB30 compared to other composite scaffolds. The results demonstrated that the prepared GCB30 scaffold could be a better candidate as bone substitute material for its higher bioactivity in bone tissue regeneration.

Preparation and characterization of gelatin-chitosan-nanoß-TCP based scaffold for orthopaedic application.

The primary aim of this study was to fabricate gelatin/chitosan/ß-TCP (GCT) composite scaffold to improve its compressive mechanical behaviour and in-vivo biocompatibility with predictable degradation rate. Beta tricalcium phosphate (ß-TCP) powder was synthesized in size range between 70-100 nm using aqueous precipitation route at a fixed Ca/P molar ratio of 1.5:1 at pH 10 and after subsequent heat treatment of as precipitated powder at 800 °C for 4 hours. The composite scaffolds were fabricated using solid-liquid phase separation of the slurry containing gelatin, chitosan, ß-tricalcium phosphate in varying proportion and subsequent lyophilisation of the phase separated mixture. The prepared scaffolds exhibited high porosity (>80%) with pore sizes ranging between 78-382 µm as determined using Hg-porosimetry. SEM result revealed that incorporation of ß-TCP to the extent of 30 wt% resulted in well-shaped and uniformly distributed interconnected pores of average pore size of 120 ±â€¯18.6 µm in it. Compressive strength of the scaffolds was increased from 0.8 MPa to 2.45 MPa on increase in ß-TCP content from 10 wt%-30 wt% in the prepared scaffold. Human Umbilical Cord derived mesenchymal stem cells (MSCs) exhibited higher degree of lamellopodia and fillopodia extensions and better spreading behaviour onto GCT30 scaffold. MTT assay and immunocytochemistry studies with cultured MSCs revealed that GCT30 scaffolds were more conducive to MSC's proliferation and differentiation into osteoblast lineage. In vivo implantation of GCT30 scaffold subcutaneously into mice did not indicate any significant inflammatory reaction, but ongoing vascularization.

MgAl- Layered Double Hydroxide Nanoparticles for controlled release of Salicylate.

Layered double hydroxides (LDHs), have been known for many decades as catalyst and ceramic precursors, traps for anionic pollutants, and additives for polymers. Recently, their successful synthesis on the nanometer scale opened up a whole new field for their application in nanomedicine. Here we report the efficacy of Mg1-xAlx (NO3)x (OH)2 LDH nanoparticles as a carrier and for controlled release of one of the non-steroidal anti-inflammatory drugs (NSAID), sodium salicylate. Mg1-xAlx (NO3)x (OH)2.nH2O nanoparticles were synthesized using co-precipitation method from an aqueous solution of Mg(NO3)2.6H2O and Al(NO3)3.9H2O. Salicylate was intercalated in the interlayer space of Mg-Al LDH after suspending nanoparticles in 0.0025(M) HNO3 and 0.75 (M) NaNO3 solution and using anion exchange method under N2 atmosphere. The shift in the basal planes like (003) and (006) to lower 2θ value in the XRD plot of intercalated sample confirmed the increase in basal spacing in LDH because of intercalation of salicylate into the interlayer space of LDH. FTIR spectroscopy of SA-LDH nano hybrid revealed a red shift in the frequency band of carboxylate group in salicylate indicating an electrostatic interaction between cationic LDH sheet and anionic drug. Differential thermal analysis of LDH-SA nanohybrid indicated higher thermal stability of salicylate in the intercalated form into LDH as compared to its free state. DLS studies showed a particle size distribution between 30-60 nm for pristine LDH whereas salicylate intercalated LDH exhibited a particle size distribution between 40-80nm which is ideal for its efficacy as a superior carrier for drugs and biomolecules. The cumulative release kinetic of salicylate from MgAl-LDH-SA hybrids in phosphate buffer saline (PBS) at pH7.4 showed a sustained release of salicylate up to 72h that closely resembled first order release kinetics through a combination of drug diffusion and dissolution of LDH under physiological conditions. Also the cytotoxicity tests performed revealed the less toxic nature of the nanohybrid as compared to the bare SA drug.

Preparation and Evaluation of Gelatin-Chitosan-Nanobioglass 3D Porous Scaffold for Bone Tissue Engineering.

The aim of the present study was to prepare and characterize bioglass-natural biopolymer based composite scaffold and evaluate its bone regeneration ability. Bioactive glass nanoparticles (58S) in the size range of 20-30 nm were synthesized using sol-gel method. Porous scaffolds with varying bioglass composition from 10 to 30 wt% in chitosan, gelatin matrix were fabricated using the method of freeze drying of its slurry at 40 wt% solids loading. Samples were cross-linked with glutaraldehyde to obtain interconnected porous 3D microstructure with improved mechanical strength. The prepared scaffolds exhibited >80% porosity with a mean pore size range between 100 and 300 microns. Scaffold containing 30 wt% bioglass (GCB 30) showed a maximum compressive strength of 2.2 ± 0.1 MPa. Swelling and degradation studies showed that the scaffold had excellent properties of hydrophilicity and biodegradability. GCB 30 scaffold was shown to be noncytotoxic and supported mesenchymal stem cell attachment, proliferation, and differentiation as indicated by MTT assay and RUNX-2 expression. Higher cellular activity was observed in GCB 30 scaffold as compared to GCB 0 scaffold suggesting the fact that 58S bioglass nanoparticles addition into the scaffold promoted better cell adhesion, proliferation, and differentiation. Thus, the study showed that the developed composite scaffolds are potential candidates for regenerating damaged bone tissue.

Development of gelatin-chitosan-hydroxyapatite based bioactive bone scaffold with controlled pore size and mechanical strength.

Hydroxyapatite-chitosan/gelatin (HA:Chi:Gel) nanocomposite scaffold has potential to serve as a template matrix to regenerate extra cellular matrix of human bone. Scaffolds with varying composition of hydroxyapatite, chitosan, and gelatin were prepared using lyophilization technique where glutaraldehyde (GTA) acted as a cross-linking agent for biopolymers. First, phase pure hydroxyapatite-chitosan nanocrystals were in situ synthesized by coprecipitation method using a solution of 2% acetic acid dissolved chitosan and aqueous solution of calcium nitrate tetrahydrate [Ca(NO3)2,4H2O] and diammonium hydrogen phosphate [(NH4)2H PO4]. Keeping solid loading constant at 30 wt% and changing the composition of the original slurry of gelatin, HA-chitosan allowed control of the pore size, its distribution, and mechanical properties of the scaffolds. Microstructural investigation by scanning electron microscopy revealed the formation of a well interconnected porous scaffold with a pore size in the range of 35-150 µm. The HA granules were uniformly dispersed in the gelatin-chitosan network. An optimal composition in terms of pore size and mechanical properties was obtained from the scaffold with an HA:Chi:Gel ratio of 21:49:30. The composite scaffold having 70% porosity with pore size distribution of 35-150 µm exhibited a compressive strength of 3.3-3.5 MPa, which is within the range of that exhibited by cancellous bone. The bioactivity of the scaffold was evaluated after conducting mesenchymal stem cell (MSC) - materials interaction and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay using MSCs. The scaffold found to be conducive to MSC's adhesion as evident from lamellipodia, filopodia extensions from cell cytoskeleton, proliferation, and differentiation up to 14 days of cell culture.

Effect of grain size on mechanical, surface and biological properties of microwave sintered hydroxyapatite.

Hydroxyapatite (HA) compacts having average grain sizes of 168±0.086 nm, 1.48±0.627 µm and 5.01±1.02 µm are processed from synthesized HA powder by microwave sintering at varying sintering temperature for different times. Superior mechanical and biological properties are shown by nano-grain HA compacts as compared to their micron grained counterparts. Compressive strength, indentation hardness, and indentation fracture toughness are increased with the decrease in HA grain size. The highest surface energy and maximum wettability are exhibited by nano-grain HA. HA compacts are assessed for cell-material interaction by SEM, MTT and immunochemistry assays using human osteoblast cell line for 1, 5 and 11 days. MTT assays showed higher number of living cells and faster proliferation on nano-grain HA surface. Osteoblast cells on nano-grain HA surface expressed significantly higher amount of vinculin and alkaline phosphatase (ALP) protein markers for cell adhesion and differentiation respectively. This study shows the effect of grain size on physical, mechanical and in vitro biological properties of microwave sintered HA compacts.

Microwave-processed nanocrystalline hydroxyapatite: simultaneous enhancement of mechanical and biological properties.

Despite the excellent bioactivity of hydroxyapatite (HA) ceramics, poor mechanical strength has limited the applications of these materials primarily to coatings and other non-load-bearing areas as bone grafts. Using synthesized HA nanopowder, dense compacts with grain sizes in the nanometer to micrometer range were processed via microwave sintering between 1000 and 1150 degrees C for 20 min. Here we demonstrate that the mechanical properties, such as compressive strength, hardness and indentation fracture toughness, of HA compacts increased with a decrease in grain size. HA with 168 +/- 86 nm grain size showed the highest compressive strength of 395 +/- 42 MPa, hardness of 8.4+/-0.4 GPa and indentation fracture toughness of 1.9 +/- 0.2 MPa m(1/2). To study the in vitro biological properties, HA compacts with grain size between 168 nm and 1.16 microm were assessed for in vitro bone cell-material interactions with human osteoblast cell line. Vinculin protein expression for cell attachment and bone cell proliferation using MTT assay showed that surfaces with finer grains provided better bone cell-material interactions than coarse-grained samples. Our results indicate simultaneous improvements in mechanical and biological properties in microwave sintered HA compacts with nanoscale grain size.