Pure Hydroxyapatite Research Articles

Tackling the challenges facing the clinical applications of pure PEO hydroxyapatite layers: Co-deposition of YSZ nanoparticles

This contribution endeavored to enhance the overall characteristics of hydroxyapatite-Yttria-stabilized ZrO2 (HAp-YSZ) composite coating deposited on the Ti6Al4V metallic implant using a plasma electrolyte oxidation (PEO) technique. The influence of the YSZ nanoparticles concentration, in the range of 0–5 g/L, in the electrolyte on the final performance of the deposits is treated. While the increased concentration of the nanoparticles had no marked effect on the phase composition, a denser and more compact layer is obtained when 3 g/L YSZ is loaded. An increase of 42.8% in microhardness and 42% in bonding strength is obtained for composite coating compared to the HAp one. The corrosion behavior of the samples was studied by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization assays. Results showed a 67% decrease in corrosion current density with the included nanoparticles. The in vitro bioactivity of the coated implants was examined after 7 days of immersion in simulated body fluid (SBF). All of the PEO coatings stimulated the apatite growth irrespective of the nanoparticles’ concentration. In view of a possible application in tissue engineering, in vitro biocompatibility tests, using SAOS-2 cell line, were carried out. The obtained results show the positive influence of the added YSZ nanoparticles on the cell viability and proliferation. The antibacterial activity of the coatings against Escherichia coli pathogenic bacteria was addressed. The higher the nanoparticle loading, the larger the inhibition zone is observed. The developed metallic-ceramic hybrid system is believed to open numerous possibilities in efficient corrosion-resistant, anti-bacterial, and bioactive dental implants.

Crystallographic dependency of waste cow bone, hydroxyapatite, and β-tricalcium phosphate for biomedical application

In this research, waste cow bone was chosen as a sustainable source of biomaterials in pure hydroxyapatite form and synthesized hydroxyapatite (HAP) was prepared as a biphasic HAP (hydroxyapatite and β-tricalcium phosphate phase) and subsequently pure β-tricalcium phosphate (β-TCP). The samples were characterized by employing X-Ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) instrumentation, and in-depth crystallographic analysis was performed by calculating crystallite size, lattice parameters, HAp percentage, the volume fraction of β-TCP, β-TCP percentage, crystallinity index, degree of crystallinity, microstrain, and dislocation density. Excellent results was noticed for biocompatible properties such as cytotoxicity, hemolysis, and antimicrobial (E. coli, S. aureus, and A. niger). A relationship was established among the synthesized products and the crystallographic parameters.

Impact of graft architecture of PEGylated copolymers assembly on hydroxyapatite in the differential regulation of initial cell and bacterial adhesion

Synthetic pure hydroxyapatite (HA), though widely investigated as an artificial orthopedic implant material, has neither anti-infection properties nor innate interfacial bioactivity. Ideally, surface modification of this material needs to be developed with simultaneous anti-microbial capacity and superior cytocompatibility. Herein, graft copolymers of a PAA backbone functionalized with a high density of polyethylene glycol (PEG), and varying grafting densities of cyclic Arg-Gly-Asp-d-Phe-Cys peptides (cRGD) end-grafted onto the PEG chains have been designed and synthesized. Systematic study on the grafted anchoring groups first indicates a synergistic binding mechanism of the copolymer to HA surface, involving electrostatic interaction of the protonated amino (–NH3+) with negatively charged HA, assisted with coordination bonding through the nitrodopamine (ND) group. The PEGylated graft copolymers are demonstrated to firmly adsorb to the HA surface as an ultrathin self-assembly layer from a HEPES buffer solution, showing stability with insignificant desorption and effective inhibition of non-specific protein adsorption evaluated by XPS and QCM-D assays. Direct adhesion assays confirm that HA, modified with the density-optimized cRGD/PEG-functionalized graft polymer, can considerably promote osteoblast attachment, while preventing different strains of bacteria adhesion in the initial phase.

Effect of reaction time, heating and stirring rate on the morphology of HAp obtained by hydrothermal synthesis

Hydroxyapatite (HAp) whiskers were prepared in reaction of calcium lactate pentahydrate and orthophosphoric acid. Synthesis were carried out in different conditions with using hydrothermal reactor. The benefit of the hydrothermal technique is the simple and precise control of the HAp crystals morphology, which is achieved by employing varying initial concentrations of starting reagents as well as different conditions of synthesis. The effect of time of synthesis, stirring and heating rate of the reaction on HAp morphology and composition was investigated. During the synthesis the following experimental parameters were varied independently: time of synthesis (3, 5, 7 h), stirring rate (0, 62.5, 125, 250, 500, 750 rpm), the reaction heating rate (0.2, 0.5, 0.7, 1.0, 1.5, 2.5 °C min−1). All syntheses were carried out with the constant molar Ca/P ratio of 1.67 in starting solutions, which is equivalent to that of stoichiometric HAp. The Ca2+ ion concentrations in starting solutions for synthesis were 0.05 and 0.1 mol dm−3. Syntheses were carried out under 20 bar. The obtained products were characterized using different method like XRD, SEM, and FTIR. It was shown that the significant majority of samples prepared were identified as pure HAp.

CuO/HAp composites: Excellent dielectric materials

The present study deals with the dielectric properties of hydroxyapatite based nanocomposites. Hydroxyapatite (HAp) ceramic has been prepared by facile wet chemical precipitation technique. The synthesized HAp is used as a matrix material and copper oxide (CuO) is used as a reinforcing material for the preparation of composites. The CuO/HAp particle reinforced composites have been developed just by mixing them mechanically with variable concentrations. These composites are characterised by X-ray diffraction, and FTIR techniques. The dielectric properties like dielectric constant, dissipation factor and AC conductivity were investigated in the frequency range 10 Hz–2 MHz. All CuO blended composites show higher dielectric constant than pure HAp. Composite with 60% HAp–40% CuO has exhibited highest dielectric constant. The composites show a trend of gradual decrease in dielectric constant and dielectric loss with increase in frequency. The AC conductivity remains constant in low frequency region and increases linearly at high frequencies. The dielectric properties are found to be the function of concentration of metal oxide particles. The composites may be used for high k-material applications.

A low-cost approach to develop silica doped Tricalcium Phosphate (TCP) scaffold by valorizing animal bone waste and rice husk for tissue engineering applications

In the present study Hydroxyapatite (HAp) derived Tricalcium Phosphate (TCP) and Silica (SiO2) based scaffold was successfully fabricated for the first time by effective utilizing various waste such as animal waste bone (AWB) and rice husk (RH) as a source of HAp and SiO2 respectively. Scaffold development involved simple steps comprising of segregation of waste materials followed by sample preparation through die compaction and sintering (1000 °C and 1300 °C). Advanced characterization techniques like XRD, SEM, TEM, and FTIR were employed to study the properties of the waste materials as well as the developed composite scaffold. The presence of silica from RH combines with the HAp during high temperature sintering and initiates the phenomenon of phase transformation of HAp to TCP along with the formation of a glassy phase. The extent of phase transformation increases as the wt% of RH increases. XRD analysis revealed the development of different phases. SEM microstructure shows that the addition of silica restricts the grain growth and supports the formation of crystalline glassy phase termed as Si-TCP. FTIR results confirmed the presence of phosphate, carbonate, and hydroxyl groups in the sintered samples. The porosity of the scaffold was in the range of 34–61% and the compressive strength was up to 4.1 MPa. The SEM images of scaffold dipped in simulated body fluid (SBF) shows formation of apatite layer throughout the surface. The bioactivity of the scaffold was highly influenced by the addition of silica in the HAp matrix. The apatite forming ability of the developed porous was much greater than that of pure HAp for the same incubation period. The obtained properties of the developed scaffold are comparable to that of natural bone. Thus the present work creates an opportunity to use AWB for the development of composite for tissue engineering applications.

Exotic FeII/FeIII Local Environments in the Hexagonal Channels of Hydroxyapatite.

In this fundamental solid-state chemistry study, two sample series were investigated in depth: iron(III)-doped hydroxyapatite (HA) compounds obtained from a co-sintering process of hematite and pure HA under air and iron(III)-doped HA compounds obtained from a co-sintering process from iron(II) acetate and pure HA under an argon atmosphere. X-ray diffraction, UV-visible, Fourier transform infrared, 1H and 31P NMR, electron paramagnetic resonance (EPR,) and Mössbauer spectroscopy methods were coupled to unravel the Fe valence states, the interactions with other anionic species (OH- and PO43-), and finally the complex local environments in hexagonal channels in both the series. In particular, we highlighted the associated mechanism to ensure electroneutrality with a focus on deprotonation versus calcium substitution. By diverging mechanisms, Fe3+ and Fe2+ ions were found to be located in different coordinated sites: 4(+1) coordinated site for Fe3+ and 2(+3) coordinated site for Fe2+ and clearly associated with very different Mössbauer and EPR signatures as various absorption bands (leading to different sample colors).

Development and evaluation of hydroxytite-based anti-microbial surface coatings on polydopamine-treated porous 3D-printed Ti6Al4V alloys for overall biofunctionality

The current investigation aims to develop hydroxyapatite-based biofunctional composite coatings on polydopamine-treated porous 3D-printed Ti6Al4V alloy implant specimens for orthopedic uses. The porous 3D-printed implants based on Ashby Gibson’s mathematical model for cellular materials are fabricated at a 65% level of porosity, so as to attain the mechanical strength of human bones. Further, the addition of strontium and silver in hydroxyapatite for improved biocompatibility of the 3D-printed implant to enhance its biofunctionality and its validation is performed. The resulting coated substrates are subjected to a series of morphological, elemental, phase, mechanical, and biological tests. When subjected to the uniaxial compression, the values for modulus of elasticity and yield strength of 3D-printed substrates are compared to the targeted value of elastic modulus and yield strength for the human bones (10–30 GPa and 148–240 MPa, respectively). The effect of polydopamine-treated 3D-printed Ti6Al4V substrates on the coating compositions of calcium and phosphorus has been compared to the untreated samples. The coating thickness and adhesion strength have been calculated and compared for different coating groups. All the samples, except untreated pure hydroxyapatite samples, displayed antimicrobial activity for both the gram-positive and gram-negative bacteria in the zone inhibition test. Hence, the current experiment provides a novel option to fabricate porous Ti6Al4V scaffolds, with a low-temperature surface coating to attain improved biofunctionality for orthopedic applications.

Biological characterization of the zinc-modified hydroxyapatite coated by a pulsed laser deposition method

Pure Hydroxyapatite (Ca10(PO4)6(OH)2) and Zn-HA nanoparticles were successfully deposited on steel substrates, and laser ablation was performed by the pulsed laser deposition (PLD) technique using an Nd: YAG laser (λ = 532 nm, τ = 12 ns). The bioactivity of the thin film was investigated by its immersing in a simulated body fluid solution of pH 7.4 at 37 °C for incubation of 14 days. The growth of the apatite layer after immersion was studied. The analysis showed the formation of needle-like crystals after immersion in solution. Wettability angles decreased for the HA coating after post-deposition compared to pure HA coatings at room temperature and ion substitutions in bioceramics lead to wettability modification. The findings confirm that Zn doping with different concentrations improved antibacterial activity. The results demonstrate that coating the surface with bioactive materials modified with metal ions, yields good biological responses, and varied compositions differentially affect the water contact angles as well as HA layer growth.

Hydroxyapatite nanoparticles synthesized with a wide range of Ca/P molar ratios and their structural, optical, and dielectric characterization

Hydroxyapatite (HAp) nanomaterials have been synthesized via wet-chemical precipitation route with Ca/P molar ratios of 1.40, 1.60, 1.67, 1.80 and 2.00. These samples have been characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, Fourier transform-infrared spectroscopy (FT-IR), ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (DRS), X-ray powder diffraction (XRPD), Rietveld refinement and dielectric spectroscopy. Micrographs from SEM showed that the calcined HAp particles were spherical in shape and they were highly agglomerated. The chemical composition derived from EDX was in good accordance with the theoretical Ca/P ratio. FT-IR spectroscopy revealed the characteristic functional groups: PO43− and OH−. Certain peaks were observed in the diffuse reflectance spectrum which is argued to originate from O2− → Ca2+ and O2− → P5+ charge transfer transitions. Phase analysis showed the existence of single pure HAp (\(\mathrm{P}{6}_{3}/\mathrm{m}\)) only for samples with Ca/P = 1.6 and 1.67. However, HAp with Ca/P = 1.4 had tricalcium phosphate (TCP, Ca3(PO4)2) as the secondary phase, while Ca/P = 1.8 and 2.0 had CaCO3 as the secondary phase. Thermograms displayed multiple steps indicating the degradation of secondary phases at higher temperatures. Further, XRD analysis of post-TGA samples revealed that there was no change in the space group symmetry; however, the phase identified was Ca5(PO4)3(CO3)0.01(OH)1.3. The dielectric constant (\({\varepsilon }^{^{\prime}}\)) and dielectric loss (\(\mathrm{tan}\delta\)) decline with enhancing frequency corresponding well with space-charge and ionic-type polarization behaviour. The ac electrical conductivity enhanced with increasing frequency obeying the Jonscher universal power law.

Improvement of medical applicability of hydroxyapatite/graphene oxide nanocomposites via additional yttrium oxide nanoparticles

Hydroxyapatite is one of the most studied bioactive materials in the biomedical field. However, Hydroxyapatite’s low mechanical strength and low fracture toughness represent a limitation in its applications as a load-bearing biomaterial. Yttrium oxide and graphene oxide (GO) have previously been shown to enhance these mechanical characterization of hydroxyapatite (HAP) when combined in binary nanocomposites. In this study, a novel ternary nanocomposite hydroxyapatite/yttrium oxide/graphene oxide has been developed and its characteristics have been compared to the nanoparticles and binary nanocomposites of its components. The compositions of the prepared materials have been confirmed. The typical morphologies of the three components of the nanocomposites have been shown by scanning and transmission electron microscopes with HAP nanoparticles. The average roughness has decreased from 11.4 nm in the nanoparticles of the pure HAP to 7.9 nm in the ternary nanocomposite. All prepared nanocomposites have shown an acceptable slight decrease in cell viability with 96.9 ± 3.5% cell viability in the composite. The ternary nanocomposite has also shown a higher antibacterial activity compared to its individual constituents, with a zone of inhibition of 12.9 ± 1.1 mm and 12.5 ± 0.9 mm against E. coli and S. aureus, respectively, compared to no inhibition in the case of pure Hydroxyapatite.

Effect of Sensitive pH on Hydroxyapatite Properties Synthesized from Chicken Eggshell

The hydrothermal method has effectively synthesized hydroxyapatite (HA). This study aimed to analyze the effect of pH on the properties (purity, crystallinity, and size) of HA crystals. HA synthesis of chicken eggshells was carried out using the hydrothermal method at temperatures of 230 °C with pH 9 and 9.34. The characteristics of HA are determined by XRF, XRD, FTIR, and TEM. The composition of the most significant compound obtained from the results of XRF analysis is CaO (97.5%). The XRD analysis showed that the purity of HA with pH 9.00 and 9.34 obtained was 97.8 and 96.6%, with the crystallinity of 56.46 and 56.96%. It was also obtained that the size of crystal HA was 21.8 and 15.7 nm for samples synthesized at pH 9.00 and 9.34. The results showed that the purity and size of HA were affected by differences in the pH synthesis and were relatively the same for its crystallinity which directly affects the value lattice parameter. The properties of HA produced by the hydrothermal method have met the criteria for biomedical applications.

Microbial Synthesis of Hydroxyapatite-Nanocellulose Nanocomposites from Symbiotic Culture of Bacteria and Yeast Pellicle of Fermented Kombucha Tea

The strong need for the utilization of industrial by-products and biowaste increases as we transition towards a circular economy. On these grounds, the present research aims to explore the applicability of the Symbiotic Culture of Bacteria and Yeast (SCOBY), a by-product of a functional beverage industry, for applications in biomedicine. Herein, hydroxyapatite (HA)-coated SCOBY nanocellulose (SN) nanocomposite (SNHA) was synthesized via a novel biomimetic approach using Serratia marcescens strain by adopting two different in situ approaches. Characterization studies established the presence of functional groups corresponding to pure nanocellulose and HA. Microscopic analysis revealed SN fibers of the dimensions 30–50 nm surrounded by 10–15 nm rod-shaped HA crystals. The SNHA membranes were carbonated and harbored traces of metal ions. A deposition of nano-HA crystals as high as 30–50% was achieved. Overall, the synthesized SNHA membranes reflected increased stability, low crystalline nature and an ion-substituted structure resembling the natural bone; they are thereby suited for bone tissue engineering.

The improved textural properties, thermal stability, and cytocompatibility of mesoporous hydroxyapatite by Mg2+ doping

The paper demonstrated the increase of the surface area and meso- and microporosity volume with the low concentration Mg-substitution introduction during the hydroxyapatite (HA) wet method synthesis, as well as samples phase and structure evolution during the heat treatment up to 1200 °C. The incorporation of 0.1 and 1.0 mol.% Mg2+ were studied by magnetic resonance techniques including electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR), magic angle spinning nuclear magnetic resonance (MAS NMR) depending on Mg2+ content, and thermal treatment temperature. The calculation based on Density Functional Theory (DFT) was conducted and a model of the Mg2+ introduction was proposed, which correlated with the unit cell volume evaluations. Incorporation of 0.1 mol. % Mg2+ resulted in the growth of specific surface area (S) on the 37%, while 1.0 mol. % Mg-HA powders demonstrated a more than three times increase of surface area up to 86.91 m2/g compared to 23.35 m2/g for pure HA. The micro- and mesopores volume also demonstrated the near three time growing up with a total pore volume of 0.2938 mm3/g. The established properties indicated the opportunity to apply these materials for water, air, and soil purification, catalyst, as well as active phase support and bone tissue repair including drugs and proteins delivery systems. The in vitro investigations demonstrated the cytocompatibility of the bioceramic granules and confirmed the positive influence of the Mg2+ on cell viability and proliferation.

Optical nonlinear properties of hydroxyapatite based materials

Pure hydroxyapatite (HAP) and biphasic HAP/β-TCP powders were synthesized using wet chemical route. Several heat treatment procedures (900–1300 °C) have been adopted in order to investigate their thermal stability and decomposition. The powder X-ray diffraction studies were carried out to examine the sample’s phase stability. The frequency of vibrations, surface morphology, structural stability, absorption and emission spectra were analyzed using Fourier Transform Infra Red (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Laser Raman analysis, UV-Vis and Fluorescence spectroscopy respectively. The nonlinear optical investigations were explored using Z-Scan (ZS) measurement for all the heat treated samples. The nonlinear (NL) absorption coefficient and nonlinear refractive index of the samples were evaluated using closed and open aperture Z-scan procedures. The observed pattern shows the negative nonlinear refractive index due to the peak followed by a valley. Further, the samples depict saturable absorption and it is also found that the saturable absorption varies as temperature increases. The influence of temperature in the optical nonlinearity of the samples was briefly discussed.

Optimization of formation of phase pure hydroxyapatite and fabrication of electrochemically stable HAP coatings on 316L SS for orthopedic applications

AbstractImpact of sintering temperature and aging time was investigated on purity and phase of hydroxyapatite powders synthesized through sol–gel process. Phase, composition, and morphology of the prepared hydroxyapatite powders were characterized using X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR), and scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS). Plausible mechanism respective to the formation of HAP from the precursors Ca(NO3)2·4H2O and triethyl phosphite (TEP) by sol–gel process was determined from 31P NMR analysis. Further, the development of hydroxyapatite coatings on 316L SS metallic surfaces was done by varying the spin coating parameters such as spin speed, spin time, and sintering atmosphere, and their corrosion resistance behavior in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and TAFEL polarization analysis. From the results, we inferred that the HAP coatings deposited on 316L SS surfaces at 3000 rpm/min under nitrogen atmosphere sintering have shown improved corrosion resistivity. The effect of aging time, sintering atmosphere, and spin speed was evaluated in terms of corrosion resistance behavior.

Construction and properties of an osteogenic-antibacterial functionalised drug delivery system based on hydroxyapatite microspheres

Pure hydroxyapatite (HA) has attracted much attention in the field of bone repair materials due to its strong potential for bioavailability, but its low osteogenic activity and non-bacterial inhibition limits its further application in this field. Therefore, in this study, strontium (Sr)-doped hydroxyapatite (HA-Sr) microspheres with a high specific surface area were prepared without adding a templating agent. On this basis, berberine hydrochloride (BBH), a Traditional Chinese antimicrobial agent with excellent antibacterial ability, was loaded to overcome traditional limitations and construct a material with good osteogenic activity and antibacterial capacity. A series of characterization results showed the doping of Sr did not affect the physical phase and morphology of HA but altered its chemical composition and crystallinity, and HA-Sr microspheres had good microscopic morphology and ion retardation, which laid the foundation for the subsequent improvement of the integrated capacity. In vitro cell experiments showed that Sr ions could significantly promote the differentiation of rBMSCs at a range of doping concentrations. In this study, the optimal doping concentration of 3% was systematically screened by cell proliferation assay, alkaline phosphatase staining and alizarin red staining in a small concentration range (1–7%). Subsequently, BBH was loaded with 3% Sr ion-doped HA microspheres to construct the drug loading model. And the sustained release test and antibacterial test further proved that its antibacterial performance was enhanced. The combined results of these experiments indicated that this material was successfully constructed with good osteogenic activity and antibacterial property, and its biological property was greatly improved.

Improving Gas Sensing Performance of Hydroxyapatite by Incorporating Black Phosphorene

In this work, short rod-shaped hydroxyapatite (HA) nanocrystals were synthesized by hydrothermal method, and black phosphorene (BP) was prepared by ultrasonication of black phosphorous and modified by pyrrole. Different mass ratios (3%, 5%, 7%, 10%) of BP were mechanically mixed with HA to prepare BP <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$/$ </tex-math></inline-formula> HA hybrid. The structure, morphology and composition of the as-synthesized hybrid were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy and Raman spectroscopy. The gas sensing properties were studied using a chemical gas sensing system. It is found that the incorporation of BP greatly improves the sensing response of HA to ammonia, and 7% BP <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$/$ </tex-math></inline-formula> HA has the best sensing performance. Its sensing response for 100 ppm ammonia is as high as 42.3%, which is 2.75 times that of pure HA. For 1000 ppm ammonia, the response can achieve 91%. BP/HA exhibits shorter response time, good selectivity, reproducibility and long-term stability to ammonia. These results indicate that BP <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$/$ </tex-math></inline-formula> HA hybrid is a promising sensing material for ammonia at room temperature. The mechanism for the enhancement of the response to ammonia is also discussed.

Nanocomposites based on hydroxyapatite/lithium oxide and graphene oxide nanosheets for medical applications

Metal-based bioceramics are developed to imitate the natural bones to be used as bone substitutes. Different nanocomposites are synthesized using hydroxyapatite (HAP), Li2O and GO to fabricate HAP, Li2O, HAP/Li2O, HAP/GO and HAP/Li2O/GO. XRD shows the change in crystal structure upon adding the three nanocomposites to each other. Besides, FTIR and XPS explain the functional groups of the compositions and analyze their surface composition. The TEM explains the morphological changes for particles dimensions of HAP/Li2O/GO showing a length of 20 nm for HAP and a size of 6 nm for Li2O sphere. In addition, SEM graphs explained the enhancement of HAP/Li2O/GO porosity showing a particle size of 0.3–0.4 µm and length of 0.8 µm. Further, roughness parameters are improved upon adding HAP and Li2O to GO, showing a roughness average value of 57.80 nm. Moreover, the cell viability of HAP/Li2O/GO is examined and shows a maximum value of 97.4 ± 1.2%. In addition, the antibacterial activity exhibited by HAP/Li2O/GO against (Escherichia coli = E. coli) and (Staphylococcus aureus = S. aureus) showed an inhibition zone of 13.4 ± 1.2 mm 12.3 ± 1.3 mm. Adding HAP presents an improvement in surface roughness as well as cell viability and antibacterial activity. Besides, the microhardness has been improved from 2.6 ± 0.1 GPa to 3.1 ± 0.2 for pure HAP and HAP/Li2O/GO, respectively. Therefore, combining HAP, GO and Li2O results in a nanocomposite of enhanced biocompatibility and can be suggested for bone biomedical applications.

COMPARING THE EFFECTS OF TWO WET PRECIPITATION METHODS ON THE YIELD OF CHICKEN EGGSHELL-DERIVED HYDROXYAPATITE

Research into better and more improved biomaterials is at the forefront of modern biomedicine. A calcium phosphate compound known as Hydroxyapatite is one of the most bioactive and biocompatible osteoconductive ceramic materials currently known to man. It occurs naturally in the bones, teeth, and shells of some animals and the leaves, and stalks of some plants. It can also be synthesized artificially. Eggshells are very prominent sources of Hydroxyapatite and currently constitute waste, and environmental pollution due to ineffective, wrong, and incorrect disposal. In this research, two modified variants of the wet chemical precipitation method were used to produce hydroxyapatite from chicken eggshells gotten from the same source. The obtained samples were then characterized using XRD and SEM. The results of the characterization were analyzed to determine the most efficient, cost-effective, and less tedious method of production. It was discovered that although the orthophosphoric acid-based wet precipitation method was more efficient in producing phase pure hydroxyapatite, the nitric acid-based wet chemical precipitation method was found to be better than the orthophosphoric-based wet chemical precipitation method in terms of particle size, agglomeration, elemental analysis, and other observed properties.