Growth Of Hydroxyapatite Research Articles

Preparation and Characterization of Mechanical Properties of HAP/45S5 Bioglass Laminated Ceramic Composites via Spark Plasma Sintering

Hydroxyapatite (HAP) displays a high degree of similarity to the inorganic components that make up roughly 70% of human hard tissue, and it possesses exceptional biological activity and biocompatibility. It is currently internationally recognized as the most biologically active hard tissue implant material. However, its substandard mechanical properties have significantly limited the application of HAP in areas requiring load bearing or in the repair of large bone defects. In this study, HAP/45S5 bioglass laminated ceramic composites were consolidated using the spark plasma sintering (SPS) technique. The grain growth and phase transformation of HAP and 45S5 bioglass were examined at various sintering temperatures. The mechanical properties of the laminated composites were investigated. At 950 °C, the flexural strength and fracture work of the sintered body were (153.22 ± 7.7) MPa and (2049 ± 34) J·m−2, respectively. These results corresponded to the load–displacement curves and showed that the composites met the mechanical performance requirements of the support material.

Silver Nanoparticles and Simvastatin-Loaded PLGA-Coated Hydroxyapatite/Calcium Carbonate Scaffolds.

The need to develop synthetic bone substitutes with structures, properties, and functions similar to bone and capable of preventing microbial infections is still an ongoing challenge. This research is focused on the preparation and characterization of three-dimensional porous scaffolds based on hydroxyapatite (HA)-functionalized calcium carbonate loaded with silver nanoparticles and simvastatin (SIMV). The scaffolds were prepared using the foam replica method, with a polyurethane (PU) sponge as a template, followed by successive polymer removal and sintering. The scaffolds were then coated with poly(lactic-co-glycolic) acid (PLGA) to improve mechanical properties and structural integrity, and loaded with silver nanoparticles and SIMV. The scaffolds were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), ATR FT-IR, and silver and SIMV loading. Moreover, the samples were analyzed by Brillouin and Raman microscopy. Finally, in vitro bioactivity, SIMV and silver release, and antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis were evaluated. From the Brillouin spectra, samples showed characteristics analogous to those of bone tissue. They exhibited new hydroxyapatite growth, as evidenced by SEM, and good antimicrobial activity against the tested bacteria. In conclusion, the obtained results demonstrate the potential of the scaffolds for application in bone repair.

Mechanistic Insights of Amino Acid Binding to Hydroxyapatite: Molecular Dynamics Charts Future Directions in Biomaterial Design.

Extensive efforts have been made to improve the understanding of hard tissue regeneration, essential for advancing medical applications like bone graft materials. However, the mechanisms of bone biomineralization, particularly the regulation of hydroxyapatite growth by proteins/peptides, remain debated. Small biomolecules such as amino acids are ideal for studying these mechanisms due to their simplicity and relevance as protein/peptide building blocks. This study investigates the binding affinity of four amino acids including glycine (Gly), proline (Pro), lysine (Lys), and aspartic acid (Asp) to the hydroxyapatite (HAP) (100) surface through molecular dynamics simulations. Our findings reveal that aspartic acid exhibits the most energetically favorable binding affinity, attributed to its additional carboxylate group (-COO-), which facilitates stronger interactions with Ca2+ ions on the HAP surface compared to other amino acids with single carboxylate groups. This highlights the critical role of specific functional groups in modulating binding strength, emphasizing that the presence of multiple binding sites in amino acids enhances binding stability. Interestingly, the study also uncovers the significance of water-mediated interactions, as the compact water layer above the HAP surface acts as a barrier, complicating direct binding and underscoring the need to consider solvation effects in simulations. Glycine, due to its small size, demonstrates a unique ability to penetrate this tightly bound water monolayer, suggesting that molecular size influences binding dynamics. These simulations offer detailed insights into the atomic-level interactions, providing a deeper understanding of binding affinity and stability. These insights are pertinent for designing peptides or proteins with enhanced interactions with biomaterials, particularly in mimicking natural bone-binding processes.

Titanium implant modification by ZIF-8 and epigallocatechin gallate-improved bioactivity and antibacterial activity

This study explores the modification of titanium implant surfaces using ZIF-8 and epigallocatechin gallate (EGCG). The modified material was comprehensively characterized using SEM/EDS analysis and FT-IR mapping. The bioactivity of the synthesized layer was assessed through hydroxyapatite (HAp) growth tests and protein adsorption assays. The results demonstrated that the synthesized layer was evenly distributed across the titanium surface, exhibited consistent protein adsorption, and promoted HAp growth, thereby confirming its bioactive properties. These enhancements were significantly superior to those of unmodified titanium. The antimicrobial properties of the material were also investigated, showing significant inhibition of microbial growth, particularly against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Candida albicans. Notably, substantial antimicrobial activity was observed only in the systems incorporating EGCG. Specifically, titanium modified using ZIF-8 and EGCG inhibited microbial growth by 41–65 %, with C. albicans being the most susceptible, followed by E. coli and the Gram-positive species S. aureus and B. cereus. Among the tested microorganisms, P. aeruginosa demonstrated the highest resistance. The study conclusively attributes the observed antimicrobial properties to the presence of EGCG. The described modification holds significant potential for enhancing implant properties and protecting surfaces against biofilm formation.

Polydopamine-induced biomimetic mineralization strategy to generate hydroxyapatite for the preparation of carbon fiber composites with excellent mechanical properties

Living organisms have developed a miraculous biomineralization strategy to form multistage organic-inorganic composites through the orderly assembly of hard/soft substances, achieving mechanical enhancement of materials from the nanoscale to the macroscale. Inspired by biominerals, this study used polydopamine (PDA) coating as a template to induce the growth of hydroxyapatite (HAP) on the surface of carbon fibers (CFs) for enhancing the interfacial properties of the CF/epoxy resin composites. This polydopamine-assisted hydroxyapatite formation (pHAF) biomimetic mineralization strategy constructs soft/hard ordered structure on the CF surface, which not only improves the chemical reaction activity of the CFs but also increases the fiber surface roughness. This, in turn, enhances the interaction and loading delivery among the fibers and the matrix. Compared to the untreated carbon fiber/epoxy resin (CF/EP) composites, the prepared composites showed a substantial enhancement in interlaminar shear strength (ILSS), flexural strength, and interfacial shear strength (IFSS), with improvements of 45.2 %, 46.9 %, and 60.5 %, respectively. This can be attributed to the HAP nanolayers increasing the adhesion and mechanical interlocking with the CFs to the matrix. This study provides an interface modification method of biomimetic mineralization for the preparation of high strength CF composites.

Bioactivity and Antibacterial Analysis of Plasticized PLA Electrospun Fibers Reinforced with MgO and Mg(OH)2 Nanoparticles.

In this work, we focused on the bioactivity and antibacterial behavior of PLA-based electrospun fibers, efibers, reinforced with both MgO and Mg(OH)2 nanoparticles, NPs. The evolution of PLA-based efibers was followed in terms of morphology, FTIR, XRD, and visual appearance. The bioactivity was discussed in terms of hydroxyapatite growth after 28 days, considered as T28, of immersion in simulated body fluid, SBF. In particular, the biomineralization process evidenced after immersion in SBF started at T14 in both systems. The number of precipitated crystals increased by increasing the amount of both NPs. The chemical composition of the precipitated crystals was also characterized in terms of the Ca/P molar ratio after T28 of immersion in SBF, indicating the presence of hydroxyapatite on the surface of both reinforced efibers. Moreover, a reduction in the average diameter of the PLA-based efibers was observed, reaching a maximum reduction of 46 and 60% in the average diameter of neat PLA and PLA:OLA efibers, respectively, after 28 days of immersion in SBF. The antibacterial behavior of the MgO and Mg(OH)2 NPs in the PLA-based electrospun fibers was tested against Escherichia coli, E. coli, as the Gram-negative bacteria, and Staphylococcus aureus, S. aureus, as the Gram-positive bacteria, obtaining the best antibacterial activity against the Gram-negative bacteria E. coli of 21 ± 2% and 34 ± 6% for the highest concentration of MgO and Mg(OH)2 NPs, respectively.

Osteo-angiogenic activity of a micro/nano hierarchical SrSi-codoped hydroxyapatite coating on zirconium alloy

Numerous studies highlight the significance of biomimetic metallic implant surfaces for enhancing osseointegration through synergistic regulation of osteogenesis-angiogenesis. However, achieving clinical demands through singular structural or compositional biomimicry poses challenges. Therefore, the integration of both structural and compositional biomimicry, to closely emulate the host bone surface, is crucial for maximizing the biological activity of metallic implants. We synthesized a micro/nano hierarchical SrSi-codoped hydroxyapatite coating on Zr16Nb12Ti alloy through a simple microarc oxidation-hydrothermal reaction. Results revealed that Si doping enhances hydroxyapatite (HA) growth along the c-axis, forming large-sized nanorods. However, co-doping of Sr and Si inhibits grain growth by reducing crystal growth freedom, yielding a finer HA nanowire coating (MH-SrSi). MH-SrSi exhibits outstanding hydrophilicity attributed to the finer HA nanowires on the coating surface, promoting the adhesion of proteins and cells. Additionally, the released Sr and Si from MH-SrSi stimulate the secretion of osteogenesis-related proteins in osteoblasts and angiogenesis-related factors in endothelial cells, exhibiting a synergistic effect on promoting osteogenesis and angiogenesis. In vivo evaluation mirrors these results and shows that the micro/nano hierarchical structures of MH-SrSi elicited inward bone growth. Overall, MH-SrSi, combining structural biomimicry and compositional biomimicry, exhibits excellent osseointegration capability, making it a promising candidate for implant materials.

Interactions and coupling mechanisms between Anammox, partial denitrification (PD) and hydroxyapatite (HAP) biomineralization in a PD/A-HAP system

In this study, hydroxyapatite (HAP) crystallization was introduced into a partial denitrification/Anammox (PD/A) process to develop PD/A-HAP granules and achieve simultaneous removal of nitrogen and phosphorus from wastewater. During the formation of PD/A-HAP granules, an unbalanced relationship between the biomass growth and phosphorus crystallization was observed, which resulted in a mass transfer inhibition inside the system. PD and Anammox activities were both impacted by the impeded nutrient contact, and PD process was revealed to be more susceptible to inhibition. Through the regulation of COD and NO3–-N, a dynamic balance between microbial proliferation and phosphorus crystallization was achieved. As a result, high nitrogen removal efficiency (NRE) was attained at 97.8±1.2 % in the final stage of operation, accompanied by a phosphorus removal efficiency (PRE) of 59.4±2.9 %. Furthermore, the recovered phosphorus was transformed into HAP crystals and encapsulated by the PD/A biomass to form granules, which greatly promoted the settling performance of the sludge. This study underlines the importance of reconciling biomass and HAP growth for a strengthened PD/A granular sludge and an enhanced nitrogen removal system. The constructed PD/A-HAP process will expand the application of PD/A with its ability to remove phosphorus while efficiently removing nitrogen.

Preparation of calcium phosphate ion clusters through atomization method for biomimetic mineralization of enamel.

Dental enamel is a mineralized extracellular matrix, and enamel defect is a common oral disease. However, the self-repair capacity of enamel is limited due to the absence of cellular components and organic matter. Efficacy of biomimetic enamel mineralization using calcium phosphate ion clusters (CPICs), is an effective method to compensate for the limited self-healing ability of fully developed enamel. Preparing and stabilizing CPICs presents a significant challenge, as the addition of certain stabilizers can diminish the mechanical properties or biosafety of mineralized enamel. To efficiently and safely repair enamel damage, this study quickly prepared CPICs without stabilizers using the atomization method. The formed CPICs were evenly distributed on the enamel surface, prompting directional growth and transformation of hydroxyapatite (HA) crystals. The study revealed that the mended enamel displayed comparable morphology, chemical composition, hardness, and mechanical properties to those of the original enamel. The approach of repairing dental enamel by utilizing ultrasonic nebulization of CPICs is highly efficient and safe, therefore indicating great promise.

Hydrothermally synthesized-nanoscale carbonated hydroxyapatite with calcium carbonates derived from green mussel shell wastes

A hydrothermal method for exploring the benefits of a low-cost calcium carbonate precursor generated by mineral carbonation of green mussel wastes was in the study for synthesizing carbonated hydroxyapatite at various temperatures. Two typical precipitated calcium carbonates identified include vaterite and calcite particles formed by previous direct mineral carbonation. The hydrothermal assisted solution at an initial pH of 5–6, containing calcium carbonate precursor and diammonium hydrogen phosphate with a Ca/P ratio of 1.67, was autoclaved for carbonated hydroxyapatite (CHA) growth for 24 h at 50, 70, 90, and 110 °C and then allowed to air cool naturally. The hydrothermally obtained powder was subjected to additional analytical evaluation, including XRD, FTIR, and SEM/EDX analysis, providing that the crystal structure, carbonate content, and lattice constants of the A- and B-type CHA formed by varying hydrothermal temperature agreed very well with the A- and B-type carbonated hydroxyapatite as reported in the literature. The hydrothermal process could produce more than 90 wt.% of hydroxyapatite nanoparticles (17–26 nm) with minor monetite and calcite. These experimental findings may aid in synthesizing A- and B-type CHA for medical applications such as bone and enamel.

In Situ Construction of Morphologically Different Hydroxyapatite-Mineralized Structures on a Three-Dimensional Bionic Chitin Scaffold.

Slow healing at the tendon-bone interface is a prominent factor in the failure of tendon repair surgeries. The development of functional biomaterials with 3D gradient structures is urgently needed to improve tendon-bone integration. The crystalline form of hydroxyapatite (HAP) has a crucial impact on cell behavior, which directly influences protein adsorption, such as bone morphogenetic protein 2, the adhesion, proliferation, and osteogenic differentiation with cells. This work aimed to generate gradient mineral structures in situ by stabilizing calcium and phosphate ions using a polymer-induced liquid precursor process. To regulate the crystalline growth of HAP at the interface of β-chitin, this work made use of the surface properties of the organic matrix found in cuttlefish bone. These techniques allowed us to prepare an organic-inorganic composite gradient scaffold comprising plate-like HAP mineralized in situ on the surface of the scaffold and fibrous HAP in the scaffold's interior. Organic-inorganic composite gradient materials are anticipated for use in tendon-bone healing produced via the in situ construction of gradient-distributed HAP mineralization layers having varying crystalline morphologies on chitin scaffolds that possess a three-dimensional bionic structure.

Monitoring of Carbonated Hydroxyapatite Growth on Modified Polycrystalline CVD-Diamond Coatings on Titanium Substrates

Production of diamond coatings on titanium substrates has demonstrated as a promising strategy for applications ranging from biosensing to hard tissue engineering. The present study focuses on monitoring the nucleation and growth of bone-like carbonated-hydroxyapatite (C-HA) on polycrystalline diamond (PCD) synthetized on titanium substrate by means of a hot filament chemical vapor deposition (HF-CVD) method. The surface terminations of diamond coatings were selectively modified by oxidative treatments. The process of the C-HA deposition, accomplished by precipitation from simulated body fluid (SBF), was monitored from 3 to 20 days by Raman spectroscopy analysis. The coupling of morphological and structural investigations suggests that the modulation of the PCD surface chemistry enhances the bioactivity of the produced materials, allowing for the formation of continuous C-HA coatings with needle-like texture and chemical composition typical of those of the bone mineral. Specifically, after 20 days of immersion in SBF the calculated carbonate weight percent and the Ca/P ratio are 5.5% and 2.1, respectively. Based on these results, this study brings a novelty in tailoring the CVD-diamond properties for advanced biomedical and technological applications.

Facet-Controlled Growth of Hydroxyapatite for Effectively Removing Pb from Aqueous Solutions.

To address the growing concerns regarding severe water pollution, effective and environmentally friendly adsorbents must be identified. In this study, we prepared hydroxyapatite (HAp, Ca10(PO4)6(OH)2) as an eco-friendly absorbent via simple precipitation and obtained rod- (r-HAp) and plate-shaped HAp (p-HAp). The approach to obtaining p-HAp involved a low pH titration rate, promoting growth along the c-axis due to the adsorption of OH- on the (110) facet. Conversely, r-HAp was obtained by maintaining a high concentration of OH- during the initial stage through rapid pH titration, leading to a stronger restrictive effect on the growth of positively charged a(b)-planes. p-HAp demonstrated superior adsorption capacity, removing Pb through dissolution and recrystallization, achieving an impressive 625 mg/g within a 60 min reaction time compared to r-HAp. Our findings afford insights into the Pb removal mechanisms of HAp with different morphologies and can aid in the development of water purification strategies against heavy metal contamination.

Atomic arrangement analysis and crystal growth mechanism of HAp nanocrystal synthesized from amorphous calcium phosphate

AbstractThe crystal growth of hydroxyapatite (HAp) using a solvothermal method was investigated under various reaction conditions. The purpose of the present study is the synthesis of HAp nanocrystals with multiple facets and the atomic arrangement for various orientations of the crystal was clarified. HAp nanorods were obtained at 200°C after 24 h using a reaction medium of water. The atomic arrangement in HAp nanorods was examined for a characteristic facet in the direction of [21−13−] and [0110−] incidences and crystal orientation along the c‐axis of HAp nanorod was confirmed using electron microscopy. The present study clarifies the HAp crystal growth mechanism, where the adsorption of cations or anions onto the crystal facet determines the HAp crystal shape. The crystals of HAp grew along the c‐axis and became rod‐shaped suggesting that cations were adsorbed predominantly over anions.

Surface Properties of Ti65Zr Alloy Modified with TiZr Oxide and Hydroxyapatite.

Titanium-zirconium dioxide nanostructures loaded by hydroxyapatite were produced on the surface of Ti65Zr alloy. The alloy was treated by anodization with the subsequent immersion in calcium glycerophosphate (CG) solutions. The resulting surfaces present TiO2-ZrO2 nanotubular (TiZr-NT) structures enriched with hydroxyapatite (HAP). The nanotube texture is expected to enhance the surface's corrosion resistance and promote integration with bone tissue in dental implants. The TiZr-NT structure had a diameter of 73 ± 2.2 nm and a length of 10.1 ± 0.5 μm. The most favorable result for the growth of HAP in Hanks' balanced salt solution (Hanks' BSS) was obtained at a CG concentration of 0.5 g/L. Samples soaked in CG at a concentration of 0.5 g/L demonstrated in a decrease of the contact angles to 25.2°; after 3 days of exposure to Hanks' BSS, the contact angles further reduced to 18.5°. The corrosion studies also showed that the TiZr-NT structure soaked in the CG = 0.5 g/L solution exhibited the best corrosion stability.

Fabrication of biocompatible and biodegradable polyvinyl alcohol/sodium alginate blend polymers incorporating Ca2+ doped TiO2 nanocomposite 3D scaffold for biomedical applications

Development of biocompatible and biodegradable 3D scaffold for biomedical application has been challenging. Herein, the application of a novel nanocomposite 3D scaffold based on poly vinyl alcohol and sodium alginate embedded with Ca2+ doped titanium dioxide nanoparticle (PVA + SA/Ca@TiO2) as bioactive material was investigated. The 3D scaffold was prepared using a solvent casting method and characterized using FTIR, SEM, XRD and TGA to study their physiochemical properties. The spectroscopy techniques were used to confirm the formation of the required poly vinyl alcohol and sodium alginate with Ca doped TiO2 nanoparticles fillers interaction by the identification of bands. The TiOH bonds and the bonds related to the interconnected network between the inorganic and the organic components from hybrids. The PVA + SA/Ca@TiO2 nanocomposite 3D scaffold was demonstrated good bioactivity to promote nucleation and growth of hydroxyapatite (HAp) in the simulated body fluid. The PVA + SA/Ca@TiO2 nanocomposite 3D scaffold supported the growth and proliferation of 3 T3 mouse fibroblast cells with strong proliferation and cell attachment. The biocompatibility and nontoxic character of the 3D scaffold was probed using fibroblast cell with over 90 % of cell viability. It offers a potential for cell attachment and captured for biomedical application.

Synthesis of Titanium Oxide Nanotubes Loaded with Hydroxyapatite.

A simple method of synthesis of TiO2 nanotubes (TiNT) loaded with hydroxyapatite (HAP) is described. Such nanotubes find wide applications in various fields, including biomedicine, solar cells, and drug delivery, due to their bioactivity and potential for osseointegration. The Cp-Ti substrate was anodized at a constant voltage of 40 V, with the subsequent heat treatment at 450 °C. The resulting TiNT had a diameter of 100.3 ± 2.8 nm and a length of 3.5 ± 0.04 μm. The best result of the growth rate of HAP in Hanks' balanced salt solution (Hanks' BSS) was obtained in calcium glycerophosphate (CG = 0.1 g/L) when precipitates formed on the bottom and walls of the nanotubes. Structural properties, surface wettability, corrosion resistance, and growth rate of HAP as an indicator of the bioactivity of the coating have been studied. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), potentiodynamic polarization test (PPC), electrochemical impedance spectroscopy (EIS), and contact angle (CA) measurements were used to characterize HAP-loaded nanotubes (HAP-TiNT). The CA, also serving as an indirect indicator of bioactivity, was 30.4 ± 1.1° for the TiNT not containing HAP. The contact angle value for HAP-TiNT produced in 0.1 g/L CG was 18.2 ± 1.2°, and for HAP-TiNT exposed to Hanks' BSS for 7 days, the CA was 7.2 ± 0.5°. The corrosion studies and measurement of HAP growth rates after a 7-day exposure to Hanks' BSS confirmed the result that TiNT processed in 0.1 g/L of CG exhibited the most significant capacity for HAP formation compared to the other tested samples.

Surface analysis of (Ti,Mg)N coated bone fixation devices following the rabbit femur surgery.

Magnesium (Mg) enhances the bone regeneration, mineralization and attachment at the tissue/biomaterial interface. In this study, the effect of Mg on mineralization/osseointegration was determined using (Ti,Mg)N thin film coated Ti6Al4V based plates and screws in vivo. TiN and (Ti,Mg)N coated Ti6Al4V plates and screws were prepared using arc-PVD technique and used to fix rabbit femur fractures for 6 weeks. Then, mineralization/osseointegration was assessed by surface analysis including cell attachment, mineralization, and hydroxyapatite deposition on concave and convex sides of the plates along with the attachment between the screw and the bone. According to Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analyses; cell attachment and mineralization were higher on the concave sides of the plates from both groups in comparison to the convex sides. However, mineralization was significantly higher on Mg-containing ones. The mean gray value indicating mineralized area after von Kossa staining was found as 0.48 ±0.01 and 0.41 ±0.04 on Mg containing and free ones respectively. Similarly, Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) analyses showed that hydroxyapatite growth was abundant on the Mg-containing and concave sides of the plates. Enhanced mineralization and strong attachment to bone were also detected in EDS and SEM analyses of Mg-containing screws. These findings indicated that (Ti,Mg)N coatings can be used to increase attachment at the implant tissue interface due to accelerated mineralization, cell attachment, and hydroxyapatite growth.

Characterising Hydroxyapatite Deposited from Solution onto Novel Substrates: Growth Mechanism and Physical Properties.

Whilst titanium, stainless steel, and cobalt-chrome alloys are the most common materials for use in orthopaedic implant devices, there are significant advantages in moving to alternative non-metallic substrates. Substrates such as polymers may have advantageous mechanical biological properties whilst other substrates may bring unique capability. A key challenge in the use of non-metal products is producing substrates which can be modified to allow the formation of well-adhered hydroxyapatite films which promote osteointegration and have other beneficial properties. In this work, we aim to develop methodology for the growth of hydroxyapatite films on surfaces other than bulk metallic parts using a wet chemical coating process, and we provide a detailed characterisation of the coatings. In this study, hydroxyapatite is grown from saturated solutions onto thin titanium films and silicon substrates and compared to results from titanium alloy substrates. The coating process efficacy is shown to be dependent on substrate roughness, hydrophilicity, and activation. The mechanism of the hydroxyapatite growth is investigated in terms of initial attachment and morphological development using SEM and XPS analysis. XPS analysis reveals the exact chemical state of the hydroxyapatite compositional elements of Ca, P, and O. The characterisation of grown hydroxyapatite layers by XRD reveals that the hydroxyapatite forms from amorphous phases, displaying preferential crystal growth along the [002] direction, with TEM imagery confirming polycrystalline pockets amid an amorphous matrix. SEM-EDX and FTIR confirmed the presence of hydroxyapatite phases through elemental atomic weight percentages and bond assignment. All data are collated and reviewed for the different substrates. The results demonstrate that once hydroxyapatite seeds, it crystallises in the same manner as bulk titanium whether that be on a titanium or silicon substrate. These data suggest that a range of substrates may be coated using this facile hydroxyapatite deposition technique, just broadening the choice of substrate for a particular function.

A judicious approach to induce large size growth of hydroxyapatite via applying graphene modified silicon nitride nanowires

Mimicking the structure of natural bone collagen fibers/hydroxyapatite (HA) to synthesize large size of HA for accelerated bone repair remains a challenge. Herein, silicon nitride nanowires (SN)-graphene (GE) was designed by the chemical vapor deposition, forming SN-GE (SG) similar to collagen fibers. Then, the large size HA was assembled onto SG by pulsed electrochemical deposition, the SG/HA (SGH) mimics the collagen fibers/HA structure of bone. The introduction of SG induces HA to large size grow in the form of coral-like. HA can be grown on a large size inextricably with the existence of GE modified layers. On the one hand, the upright GE sheets effectively increases the surface roughness which enhances the nucleation site of HA. On the other hand, the CO provides chemical bonding and induces HA nucleation. Compared with SN/HA(SH), the porosity of SGH decreased by 71%. The average diameter of the SGH is (9.76 ± 0.25) μm. Compared with SH, the diameter of SGH is 22 times larger than the diameter of SH. Indicating that SG induces large size growth of HA. Our work can provide a general strategy for the efficient preparation of biological scaffolds with large size HA that can be used in bone tissue engineering.