Biocompatibility Of Hydroxyapatite Research Articles

Preparation and Characterization of Hydroxyapatite Based Composite Material via Cold Sintering Process

This study focuses on the synthesis of hydroxyapatite (HA) from bovine bones through calcination and subsequent combination with Polyvinyl Alcohol (PVA) using the Cold Sintering Process (CSP). The CSP, operating at lower temperatures than conventional methods, aims to preserve the bioactivity and biocompatibility of HA, crucial for biomedical applications. The research investigates the influence of HA composition, sintering temperature, and PVA content on the porosity and compressive strength of the HA-PVA composite. The Hydroxyapatite powder, obtained from calcinated bovine bones, exhibits irregular shapes and sizes with a maximum grain size of 10µm, confirmed by SEM analysis. XRD analysis validates the successful production of Hydroxyapatite, showcasing characteristic peaks. The HA/PVA composite's XRD pattern indicates the dominance of HA, with PVA present as well. The study produces 27 specimens through the CSP, varying HA composition and sintering temperature. Porosity increases with higher HA content and sintering temperature, attributed to the role of PVA in binding HA particles. Compressive strength rises with increased HA content, emphasizing HA's role in enhancing mechanical strength. The presence of porosity is mitigated by a strong bond between HA and PVA, contributing to structural integrity. This research provides insights into tailoring HA-PVA materials for biomedical applications, considering controlled porosity and mechanical strength. The CSP, with its unique advantages, emerges as a promising method for developing customized materials to meet diverse biomedical needs.

Characterization, wear behavior and biocompatibility of HA/Ti composite and functionally graded coatings deposited on Ti−6Al−4V substrate by mechanical coating technique

Characterization, wear behavior, and biocompatibility of hydroxyapatite (HA)/Ti composite coating and functionally graded coatings (FGCs) deposited on a Ti−6Al−4V substrate by a mechanical coating technique were compared. The composite coating was produced using the initial powder mixture of 50 wt.% Ti + 50 wt.% HA, while the FGC was deposited by two separate layers containing 75 wt.% Ti + 25 wt.% HA and 25 wt.% Ti + 75 wt.% HA, respectively. The XRD results exhibited that no phase changed during the deposition process. Moreover, due to the presence of Ti particles in the primary powder mixtures, a continuous interface with a superior bond was formed between the coating and the substrate, especially in the samples coated by the FGCs. The wear test results of the non-graded composite coating showed a coefficient of friction (COF) of about 0.37 with an abrupt change at the interface, while the COF of the FGCs increased from 0.32 to 0.5 with a gentle change at the interface. The SEM images of the worn surfaces indicated the dominance of the abrasive wear mechanism. The biocompatibility evaluations revealed better cell attachment and proliferation of the FGC-coated samples.

In vitro and in vivo biological performance of hydroxyapatite from fish waste

The aim of this study was to evaluate biocompatibility of hydroxyapatite (HAP) from fish waste using in vitro and in vivo assays. Fish samples (whitemouth croaker - Micropogonias furnieri) from the biowaste was used as HAP source. Pre-osteoblastic MC3T3-E1 cells were used in vitro study. In addition, bone defects were artificially created in rat calvaria and filled with HAP in vivo. The results demonstrated that HAP reduced cytotoxicity in pre-osteoblast cells after 3 and 6 days following HAP exposure. DNA concentration was lower in the HAP group after 6 days. Quantitative RT-PCR did not show any significant differences (p > 0.05) between groups. In vivo study revealed that bone defects filled with HAP pointed out moderate chronic inflammatory cells with slight proliferation of blood vessels after 7 and 15 days. Chronic inflammatory infiltrate was absent after 30 days of HAP exposure. There was also a decrease in the amount of biomaterial, being followed by newly formed bone tissue. All experimental groups also demonstrated strong RUNX-2 immoexpression in the granulation tissue as well as in cells in close contact with biomaterial. The number of osteoblasts inside the defect area was lower in the HAP group when compared to control group after 7 days post-implantation. Similarly, the osteoblast surface as well as the percentage of bone surface was higher in control group when compared with HAP group after 7 days post-implantation. Taken together, HAP from fish waste is a promising possibility that should be explored more carefully by tissue-engineering or biotechnology.

Biocompatibility of Hydroxyapatite (HAp) derived from clamshell as active ingredients in sunscreen product

Commercially, Avobenzone and Oxybenzone act as absorber of UVA and UVB while titanium dioxide (TiO2) and zinc oxide (ZnO) are the physical “blockers” of UV radiation in sunscreen formulation. These active ingredients are known to cause photo-allergic reactions, while others are suspected as estrogen disrupters. Due to this concern, hydroxyapatite (HAp) is derived from clam shell in order to replace Avobenzone and Oxybenzone as organic component in UV absorber. The HAp has arisen as potential candidates to replace synthetic chemicals in sunscreens due to its properties that contain calcium, phosphate, chitin and protein that gives a great result in absorbing UV light. HAp is added into emulsion of sunscreen lotion and analyzed using thermal, spectroscopy and skin analysis in order to determine the potential results. The use of this biomaterial namely HAp is an alternative for the safe, organic, less chemical and good cosmetic product.

Current Challenges and Innovative Developments in Hydroxyapatite-Based Coatings on Metallic Materials for Bone Implantation: A Review

Biomaterials are in use for the replacement and reconstruction of several tissues and organs as treatment and enhancement. Metallic, organic, and composites are some of the common materials currently in practice. Metallic materials contribute a big share of their mechanical strength and resistance to corrosion properties, while organic polymeric materials stand high due to their biocompatibility, biodegradability, and natural availability. To enhance the biocompatibility of these metals and alloys, coatings are frequently applied. Organic polymeric materials and ceramics are extensively utilized for this purpose due to their outstanding characteristics of biocompatibility and biodegradability. Hydroxyapatite (HAp) is the material from the ceramic class which is an ultimate candidate for coating on these metals for biomedical applications. HAp possesses similar chemical and structural characteristics to normal human bone. Due to the bioactivity and biocompatibility of HAp, it is used for bone implants for regenerating bone tissues. This review covers an extensive study of the development of HAp coatings specifically for the orthopaedic applications that include different coating techniques and the process parameters of these coating techniques. Additionally, the future direction and challenges have been also discussed briefly in this review, including the coating of HAp in combination with other calcium magnesium phosphates that occur naturally in human bone.

Synthesis and potential of skipjack tuna bone hydroxyapatite as bone tissue engineering biomaterial

Hydroxyapatite Caio(P04)e(OH)2 is an alloplast material that is used to increase bone regeneration. It can be synthesis by processing natural materials such as fish bones. The purpose of this study was to synthesize hydroxyapatite from natural resources skipjack tuna (Katsuwonus pelamis) bones with precipitation method. Then, characterize hydroxyapatite morfology with FESEM and its biocompatibility using the preosteoblast MC3T3-E1 cell line. Skipjack tuna bone was synthesized into hydroxyapatite through precipitation method. The morphology of hydroxyapatite sample was revealed with field-emission scanning microscope FESEM. While the constituent elements were analyzed using SEM EDAX. Biocompatibility of hydroxyapatite was tested using preosteoblast cell culture. Cells were treated with different hydroxyapatite concentration 200 μglml, 100 μglml and 5 μg/ml. After incubation with C02 5% at 37°C for 24h,48h and 72h the cultore was tested for viability using MTT Cell Viability Assay Kit. Results were reported as optical density. The study showed that skipjack tuna bone produced grain-shaped particles with almost uniform sizes. The surface material appears to be agglomerates and form pores in between. Weight percentages Ca/P ratio for hydroxyapatite from skipjack tuna bones is 1.94. MTT assay showed cell viability after 3 days. These results suggest that skipjack tuna bone hydroxyapatite is has potential as bone engineering biomaterial

Comparison of subcutaneous inflammatory response to commercial and engineered zinc hydroxyapatite implants in rabbits

ABSTRACT Hydroxyapatite (HA) is widely used as a biomaterial for bone repair and metallic prostheses coating. The main limitations of the current commercial synthetic hydroxyapatite compounds include high cost and decreased availability, especially for veterinary medicine purposes. Additionally, it is thought that HA biocompatibility and bioactivity could be enhanced by the addition of metal compounds. The objective of this work was to compare the subcutaneous tissue response of commercial and engineered hydroxyapatite obtained from the bovine femur diaphysis mixed with different concentrations of hexa-hydrated Zinc Nitrate in rabbits. Twenty-Five New Zealand female rabbits were used. Five treatments were done according to HA composition (commercial HA, no Zn-HA, 0.1M Zn, 0.2M Zn, and 0.3M Zn). Each treatment was evaluated at five time-points (8, 15, 30, 60 and 90 days post-implantation). Histopathologic analysis was performed to assess inflammation by polymorphonuclear cells infiltration, neovascularization, and fibrosis. Results obtained in this work suggest that general inflammation decreased after 60 days of implantation regardless of Zn concentration. Fibrosis score was increased in the commercial HP compared to control and Zn-hydrated HA. This paper shows that bovine hydroxyapatite is a biocompatible material regardless of nitrate Zinc concentration and has the same properties of commercial hydroxyapatite.

Optimizing tribological, tensile & in-vitro biofunctional properties of UHMWPE based nanocomposites with simultaneous incorporation of graphene nanoplatelets (GNP) & hydroxyapatite (HAp) via a facile approach for biomedical applications

The present study focuses on simultaneous influence of graphene nanoplatelets (GNP) and hydroxyapatite (HAp) nanopowder on microstructural, wear, tensile and biofunctional behavior of UHMWPE based nanocomposites used in biomedical applications, with the aim to utilize GNP's mechanical strength and wear resistance, while benefitting from HAp's biocompatibility at the same time. 0.1, 0.5 and 1 wt% GNP with 10 wt% optimized concentration of HAp were added to the UHMWPE matrix through an easy two-step approach consisting of solvent mixing and ultrasonication in ethanol as a liquid media. The dried nanocomposite samples of powder were then hot pressed at an optimized temperature and pressure to ensure complete melting and flowing of the polymeric material. Tensile testing results indicated a 114% & 24% increase in elastic modulus and yield strength in the sample containing 1 wt% GNP and 10 wt% HAp, respectively, as compared to UHMWPE. However, the sample containing 0.5 wt% GNP showed greatest tensile performance with an increase of 101% and 31% improvement in elastic modulus and yield strength, which proves that the strengthening mechanism is influenced by the content of the reinforcement, especially in case of 2D reinforcing phases such as GNP. Microstructural analysis revealed the nucleating effect of GNPs on the crystalline structure of UHMWPE, to which the escalated mechanical properties could be attributed. Furthermore, the assessments disclosed the dependency of nucleating, and in consequence strengthening effect of GNPs to their concentration and apparent clustering threshold. Moreover, pin-on-disk tribological testing results showed a somewhat similar result for the coefficient of friction, which decreased by 50% with 1 wt% GNP, while the similar parameter for the sample containing 0.5 wt% GNP underwent 54% reduction. Whereas a steady decreasing pattern was observed in the case of wear rate with an 82% decrease in the sample containing 1 wt% GNP, coming to a conclusion that GNP is much more effective in improving wear properties rather than in mechanical strengthening. Biological examinations also demonstrated that HAp promises biocompatibility, osteoconductivity and the elimination of adverse cellular response, while cell adhesion was still dependent on the concentration and was affected adversely with increasing GNP. This destructive biological effect of GNPs was seemingly attributed to the functional groups of the material, or to the inherent edge-shaped structure by means of FTIR, wettability and compaction analyses.

Mechanical Properties and Biocompatibility of a Biomaterial on the Basis of Natural Hydroxyapatite and an Endodentic Cement1

The biocompatibility of hydroxyapatite is appropriate for bone substitution, but its mechanical properties have to be improved. In this work, a natural deproteinized hydroxyapatite was combined with an endodontic cement, which is used as binder, has a short setting time and suitable mechanical characteristics, and is biocompatible with live tissues. Resorption properties of both the materials are different, but combining them, it is possible to make a new biphasic composite biomaterial with good mechanical properties, a short setting time, and controllable biodegradation. The new biocomposite was implanted subcutaneously in laboratory rats for eight and fourteen weeks, and thereafter its morphological alterations and contact with the live tissue were evaluated. A histological analysis showed that the implant had not caused inflammation and had been accepted by the live tissue. Microscopic examinations during the experiment showed that each fraction of the composite was resorbed in different times, and, in such a way, a porous structure of the implanted material was formed, which is essential for interdigitation of the hard tissue into the implant. In order to determine the mechanical properties of the new composite, it was tested in compression at different loading rates.

Surface-grafted remedial hydroxyapatite nanoparticles to avoid operational infections

Development of economical bone repair materials that can avoid bone infections is a necessity. Hydroxyapatite (HA) and grafted hydroxyapatite (g-HA) were prepared by the in situ co-precipitation method and explored for controlled delivery of moxifloxacin. It was revealed that high surface area, surface charge, and low degree of crystallinity of g-HA enhanced its electrostatic interaction with an antibiotic moxifloxacin and improved in vitro release of the drug as compared to pure HA. In vitro antibacterial activity showed that drug release from HA and g-HA was effective against Staphylococcus aureus and Escherichia coli. The biocompatibility of HA and g-HA was confirmed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.

Biomineralization behavior of electrophoretic-deposited hydroxyapatite-tricalcalcium phosphate biphasic composite

Hydroxyapatite (HA) and tricalcium phosphate (TCP) coatings have been widely used as bonding layers on implants in the medical applications. In this research, nano-powders of HA is synthesized via aqueous sol-gel route. TCP is obtained by controlled heat treatment of HA phase at 700 °C. After that, these nano-powders are electrophoretically deposited on stainless steel substrates by applying 60 V for 5 min. Also, biphasic composite of these nano-powders are prepared at various HA/TCP ratios. The phase purity of HA and TCP are confirmed by means of X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis. Differential thermal analysis and thermogravimetry (DTA/TG) clearly demonstrate the thermolysis and phase formation for each phase. Fourier transformed infrared (FTIR) spectroscopy represents through elimination of unwanted ions. The electrophoretic deposition behavior of HA/TCP biphasic as well as single phase samples are compared and biomineralization test is performed by simulated blood fluid solution. The electrophoretic behavior of the samples dramatically changes by increasing the TCP content due to its larger particle. The HA films show higher thickness and lower porosity, which are gradually changes by increasing TCP content. In terms of biomineralization, suitable growth occurs in all samples. However, the most appreciable growth is taken place in HA:TCP ratio of 25:75 wt%. These results show that the biphasic HA/TCP coatings, if appropriately applied on implants by simply controlling the electrophoretic deposition parameters, can enormously improve the grafting process by combining the TCP reactivity to form porous structure and providing required species and the HA biocompatibility and strength to bond to adjacent tissues.

Bioglass and bioceramic composites processed by Spark Plasma Sintering (SPS): biological evaluation Versus SBF test

AbstractThe biocompatibility of hydroxyapatite (HA), a lab-made bioglass (BGCaMIX) with high crystallization temperature and different HA/BGCaMIX composites, produced by Spark Plasma Sintering (SPS), was tested with respect to murine osteocytes both by direct and indirect tests, in order to also investigate possible cytotoxic effects of the samples’ extracts. Previous investigations demonstrated that the samples’ bioactivity, evaluated in a simulated body fluid solution (SBF), increased with the increasing amount of BGCaMIX in the sample itself. Although none of the samples were cytotoxic, the findings of the biological evaluation did not confirm those arising from the SBF assay. In particular, the results of direct tests did not show an enhanced “biological performance” of materials with higher glass content. This finding may be due to the high release of ions and particulate from the glass phase. On the contrary, the performance of the BGCaMIX alone is better for the indirect tests, based on filtered samples’ extracts. This work further demonstrates that, when considering bioglasses and HA/bioglass composites, the results of the SBF assays should be interpreted with great care, making sure that the results arising from direct contact tests are integrated with those arising fromthe indirect ones.

Antibacterial activity and biofilm inhibition by surface modified titanium alloy medical implants following application of silver, titanium dioxide and hydroxyapatite nanocoatings

One of the most common causes of implant failure is peri-implantitis, which is caused by bacterial biofilm formation on the surfaces of dental implants. Modification of the surface nanotopography has been suggested to affect bacterial adherence to implants. Silver nanoparticles are also known for their antibacterial properties. In this study, titanium alloy implants were surface modified following silver plating, anodisation and sintering techniques to create a combination of silver, titanium dioxide and hydroxyapatite (HA) nanocoatings. Their antibacterial performance was quantitatively assessed by measuring the growth of Streptococcus sanguinis, proportion of live/dead cells and lactate production by the microbes over 24 h. Application of a dual layered silver–HA nanocoating to the surface of implants successfully inhibited bacterial growth in the surrounding media (100% mortality), whereas the formation of bacterial biofilm on the implant surfaces was reduced by 97.5%. Uncoated controls and titanium dioxide nanocoatings showed no antibacterial effect. Both silver and HA nanocoatings were found to be very stable in biological fluids with material loss, as a result of dissolution, to be less than 0.07% for the silver nanocoatings after 24 h in a modified Krebs-Ringer bicarbonate buffer. No dissolution was detected for the HA nanocoatings. Thus, application of a dual layered silver–HA nanocoating to titanium alloy implants creates a surface with antibiofilm properties without compromising the HA biocompatibility required for successful osseointegration and accelerated bone healing.

Microstructure, stability and biocompatibility of hydroxyapatite – titania nanocomposites formed by two step sintering process

In the present work, we report the characterization of TiO2-hydroxyapatite (HA) nanocomposites obtained by a two-step sintering (TSS) process of a mixture of HA and titanium hydride (TiH2) powders. The reactions underwent by TiH2 in the presence of HA and hydrogen release, and subsequently, titanium oxidation was examined by thermal analysis. A longer holding time in the second sintering stage enabled obtaining a homogenous TiO2-HA (36% rutile) composite with a thermal expansion coefficient of 11.46·10−6C−1 in the 40–1000°C range. Unconventional TSS process hinders HA decomposition to detrimental tricalcium phosphate (TCP). Wear rate of ceramics was determined by tribological measurements and the material biocompatibility was evaluated using MTT assay. Overall, cell viability results correlated with morphological observations indicated a good biocompatibility of HA-based composites at all tested concentrations. Incorporation of the TiO2 phase in HA by TSS process was found to be an efficient way to prepare bioceramics with improved performances.

In vivo evaluation of the role of carbonate ion in hydroxyapatite for bone remodeling

In vivo evaluation of the role of carbonate ion in hydroxyapatite for bone remodeling

Nanocrystalline hydroxyapatite doped with aluminium: A potential carrier for biomedical applications

Biocompatible materials based on hydroxyapatite are potentially attractive for a wide range of medical applications. The effect of aluminium substitution on the biocompatibility of hydroxyapatite (HA) under the physiochemical conditions has been investigated. Various samples of aluminium doped hydroxyapatite (Al-HA) with different concentration (0, 0.5, 1.0, 1.5, 2.0, 2.5mol%) were successfully synthesised by solution combustion method and characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM), and thermal analysis technique. XRD and TEM results reveal uniform and crystalline nature of Al-HA nanoparticles. The biocompatibility of the Al-HA nanoparticles was studied using L929 cell lines by MTT assays up to 24h. These Al-HA nanoparticles are biocompatible on cell lines L929 and do not have toxic effects for further possible in vivo applications. The results of these studies confirmed the biocompatibility of Al-HA and demonstrated the suitability for biomedical applications. The present work reveals the importance of structural, morphological, biocompatible properties of Al-HA nanoparticles and predicts the suitability for biomedical applications.

Synthesis, characterization, biocompatibility of hydroxyapatite–natural polymers nanocomposites for dentistry applications

Hydroxyapatite (HA), the main mineral component of bones and teeth, was synthesized by using the reaction between calcium nitrate tetrahydrate Ca(NO3)2∙4H2O and diammonium hydrogen phosphate (NH4)2HPO4 (DAHP) with a chemical precipitation method. The objective of this study is to utilize novel inorganic–organic nanocomposites for biomedical applications. HA is an inorganic component (75% w) and chitosan, alginate and albumin (Egg white) are organic components of nanocomposites (25% w). Nanocomposites were prepared in deionized water solutions, at room temperature, using a mechanical and magnetic stirrer for 48 h. The microstructure and morphology of sintered n-HAP were tested at different preheating temperature and laser sintering speed with scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR).

Preparation of Hydroxyapatite Composite Coatings with Interlayer of TiO<sub>2</sub> and its Corrosion Behaviors

Hydroxyapatite (HAP) composite coatings with interlayer of TiO2 on Ti6Al4V alloy were prepared by microarc oxidation and electrochemical potentiostatic method. Platelet adhesion test and electrochemical behaviors of the HAP coatings were investigated in platelet-rich plasma, Ringer's solution, Tyrode's solution and human blood at 37°C. The HAP coating was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD). TiO2 coating has round ostioles on the surface with the element of O, Na, Al, Si and Ti. The HAP coating has sheet-like, column-like and batten-like crystal with the Ca/P 1.6689. The biocompatibility of HAP coating was better than the initial coating. The results indicated that the HAP coating had better characters of anticorrosion and biocompatibility.

Effect of gamma irradiation on structural and biological properties of a PLGA-PEG-hydroxyapatite composite.

Gamma irradiation is able to affect various structural and biological properties of biomaterials In this study, a composite of Hap/PLGA-PEG and their ingredients were submitted to gamma irradiation doses of 25 and 50 KGy. Various properties such as molecular weight (GPC), thermal behavior (DSC), wettability (contact angle), cell viability (MTT assay), and alkaline phosphatase activity were studied for the composites and each of their ingredients. The results showed a decrease in molecular weight of copolymer with no change in the glass transition and melting temperatures after gamma irradiation. In general gamma irradiation can increase the activation energy ΔH of the composites and their ingredients. While gamma irradiation had no effect on the wettability of copolymer samples, there was a significant decrease in contact angle of hydroxyapatite and composites with increase in gamma irradiation dose. This study showed an increase in biocompatibility of hydroxyapatite with gamma irradiation with no significant effect on cell viability in copolymer and composite samples. In spite of the fact that no change occurred in alkaline phosphatase activity of composite samples, results indicated a decrease in alkaline phosphatase activity in irradiated hydroxyapatites. These effects on the properties of PLGA-PEG-hydroxyapatite can enhance the composite application as a biomaterial.

Hydroxyapatite incorporated into collagen gels for mesenchymal stem cell culture

Collagen gels could be used as carriers in tissue engineering to improve cell retention and distribution in the defect. In other respect hydroxyapatite could be added to gels to improve mechanical properties and regulate gel contraction. The aim of this work was to analyze the feasibility to incorporate hydroxyapatite into collagen gels and culture mesenchymal stem cells inside it. Human bone marrow mesenchymal stem cells (hMSC-BM) were used in this study. Gels were prepared by mixing rat tail type I collagen, hydroxyapatite microparticles and MSCs. After polymerization gels were kept in culture while gel contraction and mechanical properties were studied. In parallel, cell viability and morphology were analyzed. Gels became free-floating gels contracted from day 3, only in the presence of cells. A linear rapid contraction phase was observed until day 7, then a very slow contraction phase took place. The incorporation of hydroxyapatite improved gel stability and mechanical properties. Cells were randomly distributed on the gel and a few dead cells were observed all over the experiment. This study shows the feasibility and biocompatibility of hydroxyapatite supplemented collagen gels for the culture of mesenchymal stem cells that could be used as scaffolds for cell delivery in osteoarticular regenerative medicine.