Nanophase Hydroxyapatite Research Articles

New prospects in skin regeneration and repair using nanophased hydroxyapatite embedded in collagen nanofibers

This study reflects an exploitation of a composite matrix produced by electrospinning of collagen and electrospraying of nanophased hydroxyapatite (nanoHA), for skin regeneration applications. The main goal was to evaluate the effect of nanoHA, as source of localized calcium delivery, on human dermal fibroblasts, keratinocytes, and human mesenchymal stem cells (hMSCs) growth, proliferation, differentiation, and extracellular matrix production. This study revealed that calcium ions provided by nanoHA significantly enhanced cellular growth and proliferation rates and prevented adhesion of pathogenic bacteria strains typically found in human skin flora. Moreover, hMSCs were able to differentiate in both osteogenic and adipogenic lineages. Rat subcutaneous implantation of the membranes also revealed that no adverse reaction occurred. Therefore, the mechanically fit composite membrane presents a great potential to be used either as cell transplantation scaffold for skin wound regeneration or as wound dressing material in plastic surgery, burns treatment or skin diseases.

Influence of PLLA/PCL/HA Scaffold Fiber Orientation on Mechanical Properties and Osteoblast Behavior.

Scaffolds based on aligned and non-aligned poly (L-lactic acid) (PLLA)/polycaprolactone (PCL) fibers obtained by electrospinning, associated to electrosprayed hydroxyapatite (HA) for tissue engineering applications were developed and their performance was compared in terms of their morphology and biological and mechanical behaviors. The morphological results assessed by scanning electron microscopy showed a mesh of PLLA/PCL fibers (random and perfectly aligned) associated with aggregates of nanophased HA. Fourier transform infrared spectrometry confirmed the homogeneity in the blends and the presence of nanoHA in the scaffold. As a result of fiber alignment a 15-fold increase in Young’s Modulus and an 8-fold increase in tensile strength were observed when compared to non-aligned fibers. In PLLA/PCL/HA scaffolds, the introduction of nanoHA caused a remarkable improvement of the mechanical strength of this material acting as a reinforcement, enhancing the response of these constructs to tensile stress. In vitro testing was evaluated using osteoblast (MC3T3-E1) cells. The results showed that both fibrous scaffolds were able to support osteoblast cell adhesion and proliferation and that fiber alignment induced increased cellular metabolic activity. In addition, the adhesion and proliferation of Staphylococcus aureus were evaluated and a lower number of colony forming units (CFUs) was obtained in the scaffolds with aligned fibers.

Synthesis and characterisation of nanophase hydroxyapatite co-substituted with strontium and zinc

In order to develop new bioactive calcium phosphate (CaP) materials to repair bone defects, it is important to ensure these materials more closely mimic the non-stoichiometric nature of biological hydroxyapatite (HA). Typically, biological HA combines various CaP phases with different impurity ions, which substitute within the HA lattice, including strontium (Sr2+), zinc (Zn2+), magnesium (Mg2+), carbonate (CO32-) and fluoride (F-), but to name a few. In addition to this biological HA have dimensions in the nanometre (nm) range, usually 60 nm in length by 5–20 nm wide. Both the effects of ion substitution and the nano-size crystals are seen as important factors for enhancing their potential biofunctionality. The driving hypothesis was to successfully synthesise nanoscale hydroxyapatite (nHA), co-substituted with strontium (Sr2+) and zinc (Zn2+) ions in varying concentrations using an aqueous precipitation method and to understand their chemical and physical properties. The materials were characterised using Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM) techniques. The FTIR, XRD and XPS results confirmed that the nHA was successfully co-substituted with Sr2+ and Zn2+, replacing Ca2+ within the nHA lattice at varying concentrations. The FTIR results confirmed that all of the samples were carbonated, with a significant loss of hydroxylation as a consequence of the incorporation of Sr2+ and Zn2+ into the nHA lattice. The TEM results showed that each sample produced was nano-sized, with the Sr/Zn-10%nHA having the smallest sized crystals approximately 17.6 ± 3.3 nm long and 10.2 ± 1.4 nm wide. None of the materials synthesised here in this study contained any other impurity CaP phases. Therefore, this study has shown that co-substituted nHA can be prepared, and that the degree of substitution (and the substituting ion) can have a profound effect on the attendant materials’ properties.

Strontium and zinc co-substituted nanophase hydroxyapatite

It is well documented that biological hydroxyapatite (HA) differs from pure and synthetically produced HA, and contains of a mixture of calcium phosphate (CaP) phases in addition to a range of impurity ions, such as strontium (Sr2+), zinc (Zn2+), magnesium (Mg2+), fluoride (F-) and carbonate(CO32-), but to name a few. Further to this, biological apatite is generally in the form of rod (or needle-like) crystals in the nanometre (nm) size range, typically 60 nm in length by 5–20 nm wide. In this study, a range of nano-hydroxyapatite (nHA), substituted nHA materials and co-substituted nHA (based on Sr2+ and Zn2+) were manufactured using an aqueous precipitation method. Sr2+ and Zn2+ were chosen due to the significant performance enhancements that these substitutions can deliver. The materials were then characterised using Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM) techniques. The TEM results show that all of the samples produced were nano-sized, with Zn-substituted nHA being the smallest crystals around 27 nm long and 8 nm wide. The FTIR, XRD and XPS results all confirm that the materials had undergone substitution with either Sr2+ and Zn2+, for Ca2+ within the HA lattice (or both in the case of the co-substituted materials). The FTIR results confirmed that all of the samples were carbonated, with a significant loss of hydroxylation as a consequence of the incorporation of Sr2+ and Zn2+ into the HA lattice. None of the materials synthesised here in this study contained any other impurity CaP phases. Therefore this study has shown that substituted and co-substituted nanoscale apatites can be prepared, and that the degree of substitution (and the substituting ion) can have a profound effect of the attendant materials’ properties.

전기화학증착조건에 따른 임플란트 표면의 칼슘 포스페이트 코팅막의 특성

A simple electrochemical deposition method has been progressed to form a nano-phase hydroxyapatite (CaSUB10/SUB(PO₄)SUB6/SUB(OH)₂, HAp) deposited on a BN 5010SUP®/SUP dental implant. Pre-treatment of BN 5010SUP®/SUP dental implant was carried out by galvanostatic treatment step which acted as anchorage for growth of the calcium phosphate (CaP) during subsequent pulsed electrochemical deposition process. Electrochemical deposition of CaP was conducted in various condition. The phase and morphology of deposits calcium phosphate were influenced by the applied voltage, electrolyte temperature, and electrolyte ratio (Ca/P). The nano needle-like precipitates formed under 1.67 Ca/P ratio in solution at 85 ℃. The needle-like deposits transferred to the plate-like precipitates in the case of calcium (Ca) ion concentration and applied voltage. The results of in corrosion and dissolution test indicated that the HAp deposited implants acted as bio-active materials.

Optimization of nano-hydroxyapatite/poly(lactic-co-glycolic acid) coatings on magnesium substrates using one-step electrophoretic deposition

This study focuses on optimizing nanocomposite coatings of nanophase hydroxyapatite (nHA) and poly(lactic-co-glycolic acid) (PLGA) on magnesium (Mg) substrates using one-step electrophoretic deposition (EPD). The nHA, PLGA and Mg are all biodegradable in the human body, which makes them favorable for temporary implant applications. Mg and its alloys possess the elastic modulus and strength comparable to cortical bone, and thus reduce the detrimental effects of stress-shielding while providing necessary strength for load-bearing applications. The nHA is an attractive coating material for bone healing due to its osteoconductivity. PLGA promotes coating adhesion, and may neutralize the alkaline degradation products of Mg substrates. The nHA_PLGA composite coatings were deposited on Mg substrates using EPD with acetone as the electrolyte solvent. The parameters for EPD process, such as deposition voltage, time and electrolyte concentration, were studied to determine the optimal condition for creating the nHA_PLGA coating on Mg. The nHA_PLGA coating showed a desirable thickness of 65.85±11.95 µm with a complete homogenous coverage on Mg substrates when the deposition voltage of 75 V was applied for 6min using an electrolyte containing 1mg/mL nHA and 0.2mg/mL PLGA in acetone. The characterization of the coating confirmed the presence of both nHA and PLGA.

A systemic study on key parameters affecting nanocomposite coatings on magnesium substrates

Nanocomposite coatings offer multiple functions simultaneously to improve the interfacial properties of magnesium (Mg) alloys for skeletal implant applications, e.g., controlling the degradation rate of Mg substrates, improving bone cell functions, and providing drug delivery capability. However, the effective service time of nanocomposite coatings may be limited due to their early delamination from the Mg-based substrates. Therefore, the objective of this study was to address the delamination issue of nanocomposite coatings, improve the coating properties for reducing the degradation of Mg-based substrates, and thus improve their cytocompatibility with bone marrow derived mesenchymal stem cells (BMSCs). The surface conditions of the substrates, polymer component type of the nanocomposite coatings, and post-deposition processing are the key parameters that contribute to the efficacy of the nanocomposite coatings in regulating substrate degradation and bone cell responses. Specifically, the effects of metallic surface versus alkaline heat-treated hydroxide surface of the substrates on coating quality were investigated. For the nanocomposite coatings, nanophase hydroxyapatite (nHA) was dispersed in three types of biodegradable polymers, i.e., poly(lactic-co-glycolic acid) (PLGA), poly(l-lactic acid) (PLLA), or poly(caprolactone) (PCL) to determine which polymer component could provide integrated properties for slowest Mg degradation. The nanocomposite coatings with or without post-deposition processing, i.e., melting, annealing, were compared to determine which processing route improved the properties of the nanocomposite coatings most significantly. The results showed that optimizing the coating processes addressed the delamination issue. The melted then annealed nHA/PCL coating on the metallic Mg substrates showed the slowest degradation and the best coating adhesion, among all the combinations of conditions studied; and, it improved the adhesion density of BMSCs. This study elucidated the key parameters for optimizing nanocomposite coatings on Mg-based substrates for skeletal implant applications, and provided rational design guidelines for the nanocomposite coatings on Mg alloys for potential clinical translation of biodegradable Mg-based implants. Statement of SignificanceThis manuscript describes the systemic optimization of nanocomposite coatings to control the degradation and bioactivity of magnesium for skeletal implant applications. The key parameters influencing the integrity and functions of the nanocomposite coatings on magnesium were identified, guidelines for the optimization of the coatings were established, and the benefits of coating optimization were demonstrated through reduced magnesium degradation and increased bone marrow derived mesenchymal stem cell (BMSC) adhesion in vitro. The guidelines developed in this manuscript are valuable for the biometal field to improve the design of bioresorbable implants and devices, which will advance the clinical translation of magnesium-based implants.

Preparation and Evaluation of Two Apatites with Spherical Nanocrystal Morphology.

Spherical nanocrystal of apatite has been proved to be beneficial for osteoblast growth. Two apatites with spherical nanocrystal morphology were prepared in this study by chemical wet method and further sintering process. SEM exhibited that both apatites had spherical nanocrystal morphology. The crystal morphology and size was approaching to each other. XRD showed the apatites separately were hydroxyapatite and tricalcium phosphate phases. The cellular biocompatibility was evaluated by osteoblasts for these two spherical nanocrstal apatites. The MTT result indicated a higher cell proliferation rate for spherical tricalcium phosphate group. The ALP activity assay also strongly favored the tricalcium phosphate group. RT-PCR results indicated that Collagen I had a higher transcription level on the spherical tricalcium phosphate group. SEM results showed robust cell growth on the materials. It was concluded that the spherical nanophase tricalcium phosphate was superior to the cellular biocompatibility of spherical nanophase hydroxyapatite and the results were helpful in the manufacture of more suitable tissue engineering scaffolds.

Impedance spectroscopy and mechanical response of porous nanophase hydroxyapatite–barium titanate composite

The present study aims to develop the porous nanophase hydroxyapatite (HA)–barium titanate (BT) composite with reasonable mechanical and electrical properties as an electrically-active prosthetic orthopedic implant alternate. The porous samples (densification ~40–70%) with varying amounts of BT (0, 25, 35 and 100vol.%) in HA were synthesized using optimal spark plasma sintering conditions, which revealed the thermochemical stability between both the phases. The reasonably good combination of functional properties such as compressive [(236.00±44.90)MPa] and flexural [(56.18±5.82) MPa] strengths, AC conductivity [7.62×10−9(ohm-cm)−1 at 10kHz] and relative permittivity [15.20 at 10kHz] have been achieved with nanostructured HA-25vol.% BT composite as far as significant sample porosity (~30%) is concerned. Detailed impedance spectroscopic analysis was performed to reveal the electrical microstructure of developed porous samples. The resistance and capacitance values (at 500°C) of grain (RG, CG) and grain boundary (RGB, CGB) for the porous HA-25vol.% BT composite are (1.3×107 ohm, 3.1×10−11F) and (1.6×107 ohm, 5.9×10−10F), respectively. Almost similar value of activation energy (~1–1.5eV) for grain and grain boundary has been observed for all the samples. The mechanism of conduction is found to be same for porous monolithic HA as well as composite samples. Relaxation spectroscopic analyses suggest that both the localized as well as long range charge carrier translocations are responsible for conduction in these samples. The degree of polarization of porous samples has been assessed by measuring thermally stimulated depolarization current of the poled samples. The depolarization current is observed to depend on the heating rate. The maximum current density, measured for HA-25vol.% BT sample at a heating rate of 1°C/min is 2.7nA/cm2. Formation of oxygen vacancies due to the reduced atmosphere sintering contribute to the space charge polarization, which is obtained as the dominant polarization mechanism in the developed porous samples. Overall, such integrated functional responses do establish spark plasma sintered porous HA–BaTiO3 nanocomposite as potential alternative for electroactive prosthetic orthopedic implants.

Biocompatibility of Mg Ion Doped Hydroxyapatite Films on Ti-6Al-4V Surface by Electrochemical Deposition.

In this study, we prepared magnesium (Mg) doped nano-phase hydroxyapatite (HAp) films on the TiO2 nano-network surface using electrochemical deposition method. Ti-6Al-4V ELI surface was anodized in 5 M NaOH solution at 0.3 A for 10 min. Nano-network TiO2 surface were formed by these anodization steps which acted as templates and anchorage for growth of the Mg doped HAp during subsequent pulsed electrochemical deposition process at 85 degrees C. The phase and morphologies of HAp deposits were influenced by the Mg ion concentration.

Simultaneous structural and surface modifications of nanophase hydroxyapatite for improving its dissolution and bioactivity

The aim of this study was to improve the dissolution rate and bioactivity of nanophase hydroxyapatite (HA). For this purpose, simultaneous structural and surface modifications of nanophase HA was made by incorporating SiO44- into the HA structure and creating a silica layer on its surface via the sol–gel method. Characterization of the prepared nanopowders was performed by transmission electron microscopy, X-ray diffractometer, Fourier transformed infrared spectroscopy, and acid dissolution testing. An atomic absorption spectrometer was used to determine calcium ions concentration in physiological saline solution. Results revealed that the simultaneous structural and surface modifications of nanophase HA had a considerable increasing effect on calcium ion release from nanophase HA, and on surface reprecipitation rate of calcium ions, respectively. The obtained results suggest that this modified nanophase HA could be used as a new bioceramic for bone repair.

Electrophoretic deposition and characterization of nanocomposites and nanoparticles on magnesium substrates

This study introduces a triphasic design of biodegradable materials composed of nanophase hydroxyapatite (nHA), poly(lactic-co-glycolic acid) (PLGA), and magnesium (Mg) substrates for musculoskeletal implant applications. Specifically, nHA_PLGA composites and nHA nanoparticles were synthesized, deposited on three-dimensional Mg substrates using electrophoretic deposition (EPD), and characterized. The three components involved, that is, nHA, PLGA, and Mg are all biodegradable in the human body, thus promising for biodegradable implant and device applications. Mg and its alloys are attractive for musculoskeletal implant applications due to their comparable modulus and strength to cortical bone. Controlling the interface of Mg with the biological environment, however, is the key challenge that currently limits this biodegradable metal for broad applications in medical implants. This article particularly focuses on creating nanostructured interface between the biodegradable Mg and surrounding tissue for the dual purposes of (1) mediating the degradation of the Mg-based substrates and (2) potentially enhancing osteointegration. Nanophase hydroxyapatite (nHA) is an excellent candidate as a coating material due to its osteoconductivity, while the polymer phase promotes interfacial adhesion between the nHA and Mg. Moreover, the degradation products of PLGA and Mg neutralize each other. Surface characterization showed successful deposition of nHA_PLGA composite microspheres and nHA nanoparticles on Mg substrates using EPD. Mg substrates coated with nHA_PLGA composites showed greater adhesion strength when compared with nHA coating, and slower corrosion rate than nHA coated Mg and non-coated Mg. The triphasic composites of nHA, PLGA and Mg are promising as the next-generation biodegradable materials for medical applications.

Reducing bacteria and macrophage density on nanophase hydroxyapatite coated onto titanium surfaces without releasing pharmaceutical agents.

Reducing bacterial density on titanium implant surfaces has been a major concern because of the increasing number of nosocomial infections. Controlling the inflammatory response post implantation has also been an important issue for medical devices due to the detrimental effects of chronic inflammation on device performance. It has recently been demonstrated that manipulating medical device surface properties including chemistry, roughness and wettability can control both infection and inflammation. Here, we synthesized nanophase (that is, materials with one dimension in the nanoscale) hydroxyapatite coatings on titanium to reduce bacterial adhesion and inflammatory responses (as measured by macrophage functions) and compared such results to bare titanium and plasma sprayed hydroxyapatite titanium coated surfaces used clinically today. This approach is a pharmaceutical-free approach to inhibit infection and inflammation due to the detrimental side effects of any drug released in the body. Here, nanophase hydroxyapatite was synthesized in sizes ranging from 110-170 nm and was subsequently coated onto titanium samples using electrophoretic deposition. Results indicated that smaller nanoscale hydroxyapatite features on titanium surfaces alone decreased bacterial attachment in the presence of gram negative (P. aeruginosa), gram positive (S. aureus) and ampicillin resistant gram-negative (E. coli) bacteria as well as were able to control inflammatory responses; properties which should lead to their further investigation for improved medical applications.

Effect of sonication time on the characteristics of nanophase hydroxyapatite crystals synthesised by the sol–gel technique

An examination has been conducted of the effect of sonication time (25 kHz) at a constant temperature of 25°C on the structure of hydroxyapatite (HAp). Diammonium hydrogen phosphate and calcium nitrate tetrahydrate were used as starting materials. The gel formed by mixing the starting materials solution was subjected to sonication for 0, 5, 10, 20, 30 and 40 min. After sonication, HAp was dried at room temperature and calcined at 600°C for 2 h. The crystallisation, morphology and functional groups of the prepared nanoHAp were inspected by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. The XRD results revealed crystalline sizes in the range 50–58 nm and 3–5 of the crystalline fraction. The TEM results proved that the particle size of nano-HAp decreased with increasing sonication time. In addition, the FTIR spectroscopy confirmed that an increase of sonication time led to an increase in the concentration of carbonate groups

Nanotechnology in dentistry today.

A review was done of nanotechnology as it applies to dentistry today. Information was gathered from literature search, research data and material inserts in products.Nanotechnology deals with the physical, chemical and biological properties of structures and their components at nanoscale dimensions. One of the biggest contributionS to restorative and aesthetic dentistry has been nanocomposites. These composites are characterized by filler-particle sizes ≤ 100 nm and offer aesthetic and strength advantages over the current microfilled and hybrid resin-based composites. Nanoparticles for coating implant surfaces and the nanopatterning of dental implants is leading to better osseointegration and improved physiologic functions of implants, while nanophase hydroxyapatite has improved its adaptation into bone graft sites. Nano-biochips are now making oral cancer screening and diagnosis of diseases by saliva easier and more affordable.

A biocomposite of collagen nanofibers and nanohydroxyapatite for bone regeneration

This work aims to design a synthetic construct that mimics the natural bone extracellular matrix through innovative approaches based on simultaneous type I collagen electrospinning and nanophased hydroxyapatite (nanoHA) electrospraying using non-denaturating conditions and non-toxic reagents. The morphological results, assessed using scanning electron microscopy and atomic force microscopy (AFM), showed a mesh of collagen nanofibers embedded with crystals of HA with fiber diameters within the nanometer range (30 nm), thus significantly lower than those reported in the literature, over 200 nm. The mechanical properties, assessed by nanoindentation using AFM, exhibited elastic moduli between 0.3 and 2 GPa. Fourier transformed infrared spectrometry confirmed the collagenous integrity as well as the presence of nanoHA in the composite. The network architecture allows cell access to both collagen nanofibers and HA crystals as in the natural bone environment. The inclusion of nanoHA agglomerates by electrospraying in type I collagen nanofibers improved the adhesion and metabolic activity of MC3T3-E1 osteoblasts. This new nanostructured collagen–nanoHA composite holds great potential for healing bone defects or as a functional membrane for guided bone tissue regeneration and in treating bone diseases.

Investigation of Biodegradable Composite Coated Magnesium Alloy Using Optical Coherence Tomography

Optical coherence tomography (OCT) was used to characterize poly (lactic-co-glycolic acid) (PLGA) and nanophase hydroxyapatite (nHA) / PLGA coatings on magnesium (Mg) substrates before and after immersion in revised simulated body fluid (rSBF) under standard cell culture conditions. The OCT images clearly showed: the surface of the coatings, the metallic surface underneath the coatings, the presence of a dispersed phase within the polymer matrix, and defects and structural changes to the coatings. This study demonstrated the potential utility of OCT for performing quality assurance tests and for tracking the physical effects of degradation upon biomedical implants due to its ability to rapidly render easily interpreted images of sub-surface structure in a non-destructive manner.

Electrophoretic Deposition and Characterization of Biocomposites on Magnesium for Orthopedic Applications

The objective of this study is to produce a uniform and consistent nanophase hydroxyapatite (nHA) and poly (lactic-co-glycolic acid) (PLGA) coating on three-dimensional magnesium (Mg) implants using electrophoretic deposition (EPD) process. Mg is biodegradable, mechanically strong, and promising for orthopedic implant and device applications. However, currently available Mg and its alloys degrade too rapidly to meet clinical needs. To control Mg degradation and promote bone ingrowth, nHA/PLGA composite microspheres were synthesized and deposited onto Mg substrates using EPD process. Annealing was applied to improve the coating adhesion. The surface morphology, composition, and coating cross-section were examined using a scanning electron microscope and energy dispersive X-ray spectrometer. The results showed the presence of calcium, phosphorous, carbon, and oxygen peaks, indicating the successful deposition of nHA/PLGA microspheres on Mg. The corrosion resistance of the coated Mg was evaluated using the Tafel test. The results showed that the nHA/PLGA composite coating improved the corrosion resistance of Mg.

Nanostructured Ceramic and Ceramic-Polymer Composites as Dual Functional Interface for Bioresorbable Metallic Implants

ABSTRACTMillions of medical implants and devices (e.g., screws, plates, and pins) are used each year worldwide in surgery, and traditionally the components have been limited to permanent metals (e.g., stainless steel, titanium alloys) and polyester-based absorbable polymers. Because of clinical problems associated with these traditional materials, a novel class of biodegradable metallic materials, i.e., magnesium-based alloys, attracted great attention and clinical interests. Magnesium (Mg) is particularly attractive for load-bearing orthopedic applications because it has comparable modulus and strength to cortical bone. Controlling the interface of Mg with the biological environment, however, is the key challenge that currently limits this biodegradable metal for broad applications in medical devices and implants. This paper will particularly focus on creating nanostructured interface between the biodegradable metallic implant and surrounding tissue for the dual purposes of (1) mediating the degradation of the metallic implants and (2) simultaneously enhancing bone tissue regeneration and integration. Nanophase hydroxyapatite (nHA) is an excellent candidate as a coating material due to its osteoconductivity that has been widely reported. Applying nHA coatings or nHA containing composite coatings on Mg alloys is therefore promising in serving the needed dual functions. The composite of nHA and poly(lactic-co-glycolic acid) (PLGA) as a dual functional interface provides additional benefits for medical implant applications. Specifically, the polymer phase promotes interfacial adhesion between the nHA and Mg, and the degradation products of PLGA and Mg neutralize each other. Our results indicate that nHA and nHA/PLGA coatings slow down Mg degradation rate and enhance adhesion of bone marrow stromal cells, thus promising as the next-generation multifunctional implant materials. Further optimization of the coatings and their interfacial properties are still needed to bring them into clinical applications.

The facile and low temperature synthesis of nanophase hydroxyapatite crystals using wet chemistry

A simple and facile wet chemistry route was used to synthesize nanophase hydroxyapatite (HaP) crystals at low temperature. The synthesis was carried out at a pH of 11.0 and at a temperature of 37°C. The resulting samples were washed several times and subjected to further analysis. XRD studies revealed that the HaP crystals were polycrystalline in nature with a crystallite size of ~15–60±5nm. SEM-EDXA images confirmed the presence of calcium (Ca), phosphorous (P), and oxygen (O) peaks. Likewise, FTIR confirmed the presence of characteristic phosphate and hydroxyl peaks in samples. Lastly, HRTEM images clearly showed distinctive lattice fringes positioned in the 100 and 002 planes. TGA analysis shows that HaP crystals can withstand higher calcination temperatures and are thermally stable.