Search results for "hydroxyapatite"
showing 10 items of 63 documents
Nature-Inspired Effects of Naturally Occurring Trace Element-Doped Hydroxyapatite Combined with Surface Interactions of Mineral-Apatite Single Crysta…
2022
Innovative engineering design for biologically active hydroxyapatites requires enhancing both mechanical and physical properties, along with biocompatibility, by doping with appropriate chemical elements. Herein, the purpose of this investigation was to evaluate and elucidate the model of naturally occurring hydroxyapatite and the effects of doped trace elements on the function of normal human fibroblasts, representing the main cells of connective tissues. The substrates applied (geological apatites with hexagonal prismatic crystal habit originated from Slyudyanka, Lake Baikal, Russia (GAp) and from Imilchil, The Atlas Mountains, Morocco (YAp)) were prepared from mineral natural apatite wit…
Chemical modification of porous calcium hydroxyapatite surfaces by grafting phenylphosphonic and phenylphosphite acids
2006
Abstract It is well known that the incorporation of organic molecules can provide an effective route to modify the surface properties of apatite ceramics. The present study shows that phosphonates can react with calcium ions to control the formation of the hydroxyapatite structures. The grafting of C6H5PO(OH)2 (PPOH) and C6H5PO(OH)H (PPH) was used to increase the specific surface area as well as the porosity of hydroxyapatite materials. The higher specific surface area for HAp treated by PPOH is around 267 m2/g compared to the pure HAp (140 m2/g). The phenyl (C6H5) groups are removed by thermal treatment around 500 °C. After treatment at 800 °C, organoapatites (PP-HAp) are converted to stoi…
Co-deposition and characterization of hydroxyapatite-chitosan and hydroxyapatite-polyvinylacetate coatings on 304 SS for biomedical devices
2019
During the last decades, biomaterials have been deeply studied to fabricate and improve coatings for biomedical devices. Metallic materials, especially in the orthopedic field, represent the most common materials used for different type of devices thanks to their good mechanical properties. Nevertheless, low/medium resistance to corrosion and low osteointegration ability characterizes these materials. To overcome these problems, the use of biocoatings on metals substrate is largely diffused. In fact, biocoatings have a key role to confer biocompatibility features, to inhibit corrosion and thus improve the lifetime of implanted devices. In this work, the attention was focused on Hydroxyapati…
Composite Scaffolds with a Hydrohyapatite Spatial Gradient for Osteochondral Defect Repair
2018
Osteochondral defects derived by traumatic injury or aging related disease are often associated with severe joint pain and progressive loss of joint functions for millions of people worldwide and represent a major challenge for the orthopedic community. Tissue engineering offers new therapeutic approach to repair the osteochondral defects, through the production of scaffolds manufactured to mimic their complex architecture, which consists of cartilage and bone layers. Composite scaffolds based on a PLLA polymeric matrix containing hydroxyapatite (HA) as a filler were prepared through a modified thermally induced phase separation (TIPS) protocol. A suspension was prepared by adding sieved HA…
RF magnetron-sputtered coatings deposited from biphasic calcium phosphate targets for biomedical implant applications
2017
Bioactive calcium phosphate coatings were deposited by radio-frequency magnetron sputtering from biphasic targets of hydroxyapatite and tricalcium phosphate, sintered at different mass % ratios. According to Raman scattering and X-ray diffraction data, the deposited hydroxyapatite coatings have a disordered structure. High-temperature treatment of the coatings in air leads to a transformation of the quasi-amorphous structure into a crystalline one. A correlation has been observed between the increase in the Ca content in the coatings and a subsequent decrease in Ca in the biphasic targets after a series of deposition processes. It was proposed that the addition of tricalcium phosphate to th…
Formation of Calcium-Deficient Hydroxyapatite via Hydrolysis of Nano-Sized Pure Α-Tricalcium Phosphate
2015
Nano-sized pure α-tricalcium phosphate (α-TCP) fabricated by a novel synthesis approach shows great potential for a faster transformation into calcium-deficient hydroxyapatite (CDHA) than conventionally prepared α-TCP. In this work, amorphous tricalcium phosphate precursors were precipitated and treated with a solvent (water or ethanol), and dried (freeze-dried and oven-dried) before heating at 775 °C. Nanosized α-TCP powders were investigated for their phase composition and crystallinity, particle shape and size, reactivity and cellular biocompatibility. Reaction with water showed faster CDHA formation for freeze-dried powder, at 6 hours, compared to ethanol treated powders, whereas a high…
Small-sized granules of biphasic bone substitutes support fast implant bed vascularization
2015
The present study investigated the influence of granule size of 2 biphasic bone substitutes (BoneCeramic® 400-700 μm and 500-1000 μm) on the induction of multinucleated giant cells (MNGCs) and implant bed vascularization in a subcutaneous implantation model in rats. Furthermore, degradation mechanisms and particle phagocytosis of both materials were examined by transmission electron microscopy (TEM). Both granule types induced tissue reactions involving primarily mononuclear cells and only small numbers of MNGCs. Higher numbers of MNGCs were detected in the group with small granules starting on day 30, while higher vascularization was observed only at day 10 in this group. TEM analysis reve…
Galvanic deposition of Hydroxyapatite/Chitosan/Collagen coatings on 304 stainless steel
2021
The galvanic deposition method was used to deposit Hydroxyapatite/Chitosan/Collagen coatings on 304 stainless steel. Galvanic deposition is an alternative and valid way to fabricate bio-coatings with high biocompatibility and good anticorrosion properties. Physical-chemical characterizations were carried out to investigate chemical composition and morphology of the samples. Coatings consist of a mixture of calcium phosphate (Brushite and Hydroxyapatite) with chitosan and collagen. Corrosion tests were performed in the simulated body fluid (SBF) after different aging times. Results show that, in comparison with bare 304 stainless steel, coating shifts corrosion potential to anodic values and…
Immobilisation of yeast cells on the surface of hydroxyapatite ceramics
2011
Hydroxyapatite (HAP) ceramics was tested for the first time for the possibility of being used as a new carrier for the immobilisation of yeast cells that are both model organisms for eukaryotic cell investigations and producers, which is important in classical and modern biotechnological processes. It was shown that under typical immobilisation conditions yeast (Saccharomyces cerevisiae) has no affinity to HAP ceramics. A novel method for yeast immobilisation was developed. This new method includes the joint incubation of a carrier with the cells, the sedimentation and adhesion of cells on the carrier and the dehydration of obtained preparations. It was shown that the sedimentation and adhe…
Galvanic Deposition of Hydroxyapatite/Chitosan/Collagen Coatings on 304 Stainless Steel
2021
The galvanic deposition method was used to deposit Hydroxyapatite/Chitosan/Collagen coatings on 304 stainless steel. Galvanic deposition is an alternative and valid way to fabricate bio-coatings with high biocompatibility and good anticorrosion properties. Physical-chemical characterizations were carried out to investigate chemical composition and morphology of the samples. Coatings consist of a mixture of calcium phosphate (Brushite and Hydroxyapatite) with chitosan and collagen. Corrosion tests were performed in the simulated body fluid (SBF) after different aging times. Results show that, in comparison with bare 304 stainless steel, coating shifts corrosion potential to anodic values and…