Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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Graft polymerization of glycidylmethacrylate (GMA) onto coralline hydroxyapatite, (CHA) was carried out using potassium persulfate (K2S2O8) and sodium metabisulfite (Na2S2O5) as initiators in aqueous medium. To optimize the reaction conditions for getting maximum grafting yield, the concentrations of backbone, monomer, initiator, temperature and time were varied. The percent grafting was found to increase initially and then gradually decrease with respect to reaction parameters. The results obtained imply that the optimum temperature and time was 60°C and 180 min, respectively, to obtain higher grafting yield. The grafting results have been discussed and a mechanism involved in the grafting of GMA onto CHA is described. The grafted materials were analyzed with Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) measurements. The results of FT-IR confirmed the presence of epoxy group on the grafted CHA. The XRD pattern showed that there was no secondary phase in the apatite lattice due to chemical modification.

Centre for Biomaterials, Cellular and Molecular Theranostics

Vellore Campus

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Journal of Biomaterials Science, Polymer Edition

Graft polymerization of glycidylmethacrylate onto coralline hydroxyapatite

Migration of coralline hydroxyapatite (CHA) particulate system beyond the implanted surface and its slow bioresorbtion are common clinical problems particularly, periodontal defects. In this study, an attempt was made to prepare alginate incorporated CHA composite-gel as a biodegradable bone composite to alleviate the above problems. The reaction conditions were optimized by changing the concentration of alginate to achieve an ideal composite-gel. The prepared materials were analyzed by various physico-chemical methods and the results suggest that the CHA is well intact with the macromolecules of polysaccharide. The FT-IR results clearly indicate the existence of hydroxyl and amide groups in addition to the characteristic peaks of CHA in the composite-gel. The particle size of the CHA increased because of the conjugation of alginate, which is highly beneficial to prevent the particle migration of CHA upon implantation. In-vitro physiological stability and solubility of the composite-gel was carried out in phosphate buffered saline (PBS) of pH 7.4 at 37°C. The results indicate that the dissolution rate of calcium ions is more in the composite-gel than CHA alone. The phase analysis was done by X-ray powder diffraction (XRD) method and the observations show no structural changes of the CHA due to the presence of alginate. These findings suggest that the CHA-alginate composite-gel would have tremendous potential as a biodegradable bone substitute while retaining the bioactivity of CHA and immobilization of particles after implantation.

Key Engineering Materials

Biodegradable coralline hydroxyapatite composite-gel using natural alginate

Xenogeneic bone procured from the slaughterhouse waste was deproteinated by heat treatment method intended for use as a bone substitute. The effect of heat treatment was investigated by thermal analysis and by physico-chemical methods such as X-ray powder diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy. The heat treatment temperatures for the bovine bone samples were predetermined by thermogravimetric (TG) analysis. The XRD results revealed that the process of heat treatment promoted the crystallinity of bone samples, particularly at 700 and 900°C. There was no secondary phase transformation detected for heat-deproteinated bone except the presence of the hydroxyapatite (HA) phase, which indicated its phase purity even at a higher temperature. The FTIR spectra of raw bone and bone heated at 300°C indicated the presence of organic macromolecules whereas these disappeared in the samples heated at 500, 700 and 900°C, which suggested the removal of antigenic organic matters around 500°C. The same results were also confirmed quantitatively by calculating the amount of collagen using hydroxyproline estimation. There was no significant change in the TG-thermogram of bone heated at 500, 700 and 900°C, which indicated their thermal stability. These findings implied that the heat treated bone at 500°C had properties similar to carbonated HA with low crystallinity, while 700 and 900°C samples had the same with higher crystallinity. As low temperature treatment does not alter morphological and structural properties, we propose that the 500°C heat treated xenogeneic bone may act as an excellent osteogenic bone substitute.

Fulltext

Bulletin of Materials Science

Heat-deproteinated xenogeneic bone from slaughterhouse waste: Physico-chemical properties

Under microwave irradiation, carbonated hydroxyapatite (CHAp) was prepared by a unique method using goniopora as calcium precursor and di-basic calcium phosphate (CaHPO4) as phosphate precursor. The final products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric (TG) analysis. The XRD pattern confirms the formation of hydroxyapatite (HAp) without detecting any extraneous phases. The FT-IR spectrum of HAp shows trace element of carbonate ions indicating carbonate substitution into the apatite phase. The goniopora was found to decompose all the organic debris and carbonate phases at 900°C. The prepared CHAp shows no significant weight loss up to 1000°C indicating its thermal stability. In-vitro solubility test show increase in the CHAp solubility than pure HAp. These findings imply the feasibility of CHAp formation using goniopora under microwave irradiation. The prepared CHAp can be used as a potential bone substitute since it resembles biological apatite in view of physico-chemical properties.

Microwave synthesis of bloresorbable carbonated hydroxyapatite using goniopora

Demineralized xenogeneic bone (DXB) was prepared from bovine cortical tibia and graft copolymerized with glycidylmethacrylate (GMA) using a combination of potassium persulfate (K2S2O8) and sodium metabisulfite (Na2S2O5) as redox initiating system in aqueous medium. To optimize the reaction condition, the concentrations of backbone, monomer, initiator, temperature and time were varied. The percent grafting was found to increase initially and thereafter decrease in most of the cases. The optimum temperature and time were found to be 40°C and 180 minutes, respectively. The grafting results have been discussed and a reaction mechanism is proposed. Functional groups and structural changes of the graft copolymer were determined by Fourier transform infrared (FT-IR) spectroscopic method for proof of grafting and the results are discussed.

Polymer Bulletin

Grafting of glycidylmethacrylate onto demineralized xenogeneic bone in aqueous medium

Chemically and thermally treated bovine bone has been proposed as an alternative to bone grafts and synthetic bone substitutes. Fluorinated bovine hydroxyapatite (FBHA) was prepared by two different methods at low and high temperatures. The effect of reaction temperature and fluorine concentration on the crystal morphology, phase purity and functional groups were observed by X-ray diffraction (XRD) method and FT-IR spectroscopy. The XRD results indicted that [3 0 0] reflection peak was shifted towards higher angle due to fluorination. The a-axis dimensions of both the FBHA samples were found to be decreased with the fluorination. The FT-IR spectra of FBHA samples confirm partial fluorination into the hydroxyl group of bovine hydroxyapatite. The in vitro physiological stability study was performed in phosphate buffered saline (PBS) of pH 7.4 at 37 °C and the samples were found to be quite stable for about a month. These results suggest the tremendous potential of fluorinated bovine hydroxyapatite as a bone substitute due to their bioactive nature. © 2002 Elsevier Science B.V. All rights reserved.