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In this study, pure and 10% wt. Titania-Stabilised Zirconia (TiSZ) -reinforced Hydroxyapatite (HA) coatings were deposited on magnesium substrate using plasma spray as a single layer and double layer with an HVOF sprayed Ti bond coat. The coated specimens were characterised by X-ray diffraction (XRD) analysis, and scanning electron microscopy equipped with energy dispersive spectroscopy (SEM, EDS). Rockwell-C adhesion and scratch tests were performed. The corrosion behaviours in simulated body fluid (SBF) of coatings were investigated by an electrochemical corrosion test. Analyses confirmed successful coating with a dense titanium buffer layer. The double-layered HA-titanium combination offered superior corrosion resistance compared to single layers. While adding TiSZ enhanced adhesion, it compromised scratch resistance. The titanium bond coat had minimal impact on adhesion and cohesion behaviour of coatings. [ABSTRACT FROM AUTHOR]

We aimed to improve the biocompatibility and osteoinductive potential of Ti implants using a simulated intraoral hydroxyapatite (HAp) coating. We devised a novel surface treatment for aggressive induction of osteoblast adhesion and bone regeneration on the implant surface. A thin α-tricalcium phosphate (α-TCP) film was deposited on the implant surface using a pulsed Er:YAG laser. The coating was converted to HAp through artificial saliva immersion, which was confirmed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM showed needle-like HAp crystals on the Ti disks and sandblasted implant surfaces after immersion in artificial saliva for 96 h. Microcomputed tomography and histological evaluation 4 and 8 weeks after implantation into beagle dog mandibles showed that the HAp-coated implant was biocompatible and exhibited superior osteoinduction compared to that of sandblasted implants. Coating the implant surface with HAp using an Er:YAG laser has potential as a new method of the implantsurface debridement. [ABSTRACT FROM AUTHOR]

As a result of hydroxyapatite's (HAp) similarity to the mineral component of bone, it has been extensively investigated for biomedical application. To mimic the non-stoichiometric hydroxyapatite of bone or add positive features to it, different cationic and anionic substitutions have been studied. In this study, the nanocomposite coating of strontium (Sr) and silver (Ag) substituted HAp was deposited on a rarely investigated β type titanium alloy with low Young's modulus to investigate its morphological and chemical features, crystallographic structure, thickness, biocompatibility, and hydrophilicity. The coating was deposited via a little reported electrochemical method which has the advantages of both electrolytic and electrophoretic deposition. The process is simple and can be conducted under mild experimental conditions to prevent potential high-temperature induced-thermal stress complications. The chemical, morphological and crystallographic features were characterised using EDAX, FE-SEM, and XRD analysis. The coating thickness was measured using a profilometry test. The biocompatibility and wetting behaviour were evaluated by MTT assay and the sessile drop technique, respectively. The coatings have shown rod-shaped, homogenous, and nano-sized HAp particles, with a close Ca/P ratio to stoichiometric apatite; meanwhile, Sr and Ag nanosphere particles are capable of modifying its surface. The coating can support cell growth and proliferation and shows a superhydrophilic surface. [ABSTRACT FROM AUTHOR]

Oral biofilms are highly structured bacterial colonies embedded in a highly hydrated extracellular polymeric substances (EPS) matrix. This study aimed to investigate the characteristics of oral biofilm at different stages of maturation. Oral multispecies biofilms were grown anaerobically from plaque bacteria on collagen coated hydroxyapatite discs in brain heart infusion broth for one and three weeks. The volume of live bacteria and EPS matrix of the biofilms were determined by using corresponding fluorescent probes and confocal laser scanning microscopy. Atomic force microscopy (AFM) was used to quantitatively probe and correlate cell surface adhesion force of biofilms. The surface roughness was quantified in terms of the root mean square average of the height deviations. Adhesion was measured from force–distance data for the retraction of the cell from the surface. The volume of live bacteria and EPS of 3-week-old biofilms was higher than 1-week-old biofilms. The surface roughness value in 1-week-old biofilms was significantly higher than that in 3-week-old biofilms. AFM force–distance curve results showed that the adhesion force at the cell–cell interface was significantly more at-tractive than those at bacterial cells surface of both stages biofilms. Adhesion forces between the AFM tip and the surface of bacterial cell were fairly constant, whereas the cell–cell interface experienced greater adhesion forces in the biofilm's development. As oral biofilms become mature, EPS volume and cell–cell adhesion forces increase while the surface roughness decreases. [ABSTRACT FROM AUTHOR]

• The widespread use of Mg alloys as biodegradable implant materials is limited due to their rapid degradation rate. • HAp-containing PEO-coatings have attracted much attention for biomedical applications over the past decade. • The application of an HAp-containing coating can help minimize the rate of deterioration of Mg alloys, increase their biological activity, and facilitate bone formation. • HAp-containing coating reduces the rate of corrosion of Mg alloys, allowing for controlled degradation. Mg and its alloys have been introduced as promising biodegradable materials for biomedical implant applications due to their excellent biocompatibility, mechanical behavior, and biodegradability. However, their susceptibility to rapid corrosion within the body poses a significant challenge and restricts their applications. To overcome this issue, various surface modification techniques have been developed to enhance the corrosion resistance and bioactivity of Mg-based implants. PEO is a potent technique for producing an oxide film on a surface that significantly minimizes the tendency to corrode. However, the inevitable defects due to discharges and poor biological activity during the coating process remain a concern. Therefore, adding suitable particles during the coating process is a suitable solution. Hydroxyapatite (HAp) has attracted much attention in the development of biomedical applications in the scientific community. HAp shows excellent biocompatibility due to its similarity in chemical composition to the mineral portion of bone. Therefore, its combination with Mg-based implants through PEO has shown significant improvements in their corrosion resistance and bioactivity. This review paper provides a comprehensive overview of the recent advances in the preparation, characterization, corrosion behavior and bioactivity applications of HAp particles on Mg-based implants by PEO. [ABSTRACT FROM AUTHOR]

In this research, hydroxyapatite powder particles were coated on a Ti-6Al-4V alloy substrate by the plasma spraying method to create bone implants by benefitting from titanium's mechanical properties and hydroxyapatite's biological properties. Hydroxyapatite prepared by the plasma spraying method suffers from decomposition, formation of other calcium phosphate phases, weak adhesion to the substrate, and microcrack formation in the coating due to residual stresses initiated by the high temperature of the coating process. To improve the hydroxyapatite coating properties, the Ti-6Al-4V alloy was preheated, and then hydroxyapatite coating took place. The results showed that residual stress in the interface decreased, and adhesion improved by preheating the substrate. However, formation of an amorphous phase on coating was observed, resulting in a higher dissolution rate in the biological environment and weak mechanical properties compared to crystalline hydroxyapatite. Experimental results showed that heat treatment after the coating process decreased the amount of this amorphous phase and heightened the crystallinity of the coating by up to more than 60%. [ABSTRACT FROM AUTHOR]

In order to realise the biocompatibility and antibacterial activity of Ti alloy to meet the requirements of oral and orthopaedic applications, drug-loaded hydroxyapatite coatings doped with strontium were designed and constructed on the surface of Ti alloy using layer-by-layer assembly and hydrothermal treatment. The obtained coating was characterised by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The biological assays showed that the composite coating exhibited excellent biocompatibility and antibacterial activity. Therefore, based on the in vitro studies, it can be claimed that the LbL assembly and the multifunctional coating can act as a promising surface-engineering strategy for the functionalization of Ti alloy in clinical trials. [ABSTRACT FROM AUTHOR]

Polycaprolactone/hydroxyapatite (PCL/HA) composite coating was fabricated by a combination of hydrothermal and dipping methods to delay the degradation of Mg alloy AZ31 as bioresorbable materials. The PCL/HA coating was composed of nano rod-shape HA crystals and PCL filled in the space of HA crystals. Compared with the single HA coating, the binding strength between the PCL/HA composite coating and Mg alloy was obviously improved and the PCL/HA coating still adhered to the surface of AZ31 substrate even after 38 days of immersion. The electrochemical corrosion rate of HA coated sample was reduced by ten times after being filled by PCL. The electrochemical impedance spectroscopy (EIS) and immersion test results showed that the PCL/HA composite coating could provide a more effective barrier for Mg substrate than the HA coating alone. The cytocompatibility and the antibacterial property of HA coating and PCL/HA coating were evaluated by culturing with bone marrow-derived mesenchymal stem cells (BMSCs) and methicillin-resistant staphylococcus aureus (MRSA) for 24 h under direct culture conditions, respectively. The PCL/HA composite coating showed better BMSC cell compatibility, more suitable for BMSC adhesion than HA coating alone and showed a potential application prospect as a biological materials. However, from the perspective of clinical applications, the antibacterial property of PCL/HA composite coating needs to be further improved. [ABSTRACT FROM AUTHOR]

Ion substitution in hydroxyapatite (HA) lattice is a promising way to enhance its antibacterial activity and inhibit implant-related infections. In this study, HA/silver (HA/Ag) nanocomposites were synthesised through sol-gel method from two calcium (Ca) and phosphor (P) precursors. Our results showed that, by using P precursor, larger HA particles with higher crystallinity were produced, while Ca progenitor increased nucleation rate and created amorphous particles with smaller size. These findings were further confirmed by Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. Moreover, starting with P precursors shifted the index plasmon peak of Ag to the higher wavelengths (500–550 nm), providing a higher tendency to release Ag+ ions and in vitro antibacterial activity at concentration of 800 μg/mL. As a result, this study proved that HA/Ag particles could be synthesised from P precursor with better phase structure and antibacterial activity, developed for biomedical applications especially as a biomimetic coating of bone implants. [ABSTRACT FROM AUTHOR]

Globally, vast research interest is emerging towards the development of biodegradable orthopedic implants as it overcomes the toxicity exerted by non-degradable implants when fixed in the human body for a longer period. In this context, magnesium (Mg) plays a major role in the production of biodegradable implants owing to their characteristic degradation nature under the influence of body fluids. Also, Mg is one of the essential nutrients required to perform various metabolic activities by the human cells, and therefore, the degraded Mg products will be readily absorbed by the nearby tissues. Nevertheless, the higher corrosion rate in the biological environment is the primary downside of using Mg implants that liberate H 2 gas resulting in the formation of cavities. Further, in certain cases, Mg undergoes complete degradation before the healing of damaged bone tissue and cannot serve the purpose of providing mechanical support. So, many studies have been focused on the development of different strategies to improve the corrosion-resistant behavior of Mg according to the requirement. In this regard, the present review focused on the limitations of using pure Mg and Mg alloys for the fabrication of medical implants and how the calcium phosphate conversion coating alters the corrosive tendency through the formation of hydroxyapatite protective films for enhanced performance in medical implant applications. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAp) coating electrodeposition was performed on three orthogonal surfaces of duplex-annealed Ti6Al4V alloy. This approach made it possible to investigate the effect of substrate crystallographic texture on hydroxyapatite coating properties exclusively from its microstructure. The coating characteristics were evaluated by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), laser surface profilometry, and potentiodynamic polarization test. The results showed that the presence of (1010 ) low-surface energy planes leads to smaller HAp deposits of 39 ± 4 μm due to the higher nucleation rate during electrodeposition. The highest surface roughness value of 75 ± 1 μm, as well as the lowest degree of crystallinity, equal to 23.5%, belonged to the surface in which (0001) and (1120) planes of high-surface energy placed in parallel to the surface. The electrochemical test results showed that the protective efficiency of HAp coatings was the highest for the surface with (1010) planes in parallel. This was attributed to the increased thickness and the low porosity content of the coating. [ABSTRACT FROM AUTHOR]

Magnesium is a candidate metal for biodegradable implant applications for its biodegradation tendency and excellent biocompatibility. Unfortunately, the high degradation rate of magnesium and also its localized degradation in physiological conditions are the main issues for its successful implant applications. The degradation rate of magnesium has been reduced to some degree via alloying, but the localized degradation susceptibility is a great concern. For many years, hydroxyapatite (HAp), a biocompatible ceramic material, has been extensively used for bio-implant applications. Recently, a substantial amount of research has been carried out on coating HAp on magnesium-based materials for improved degradation resistance in particular and also to enhance the biocompatibility. This review article focuses on the different methods of HAp coating on magnesium-based materials and also the recent cutting-edge advancements made in the coating process for improved degradation resistance and biocompatibility. The mechanical stability of the HAp coated magnesium-based materials is also discussed. [ABSTRACT FROM AUTHOR]

MXene, as a new category of two-dimensional nanomaterials, exhibits a promising prospect in biomedical applications due to its ultrathin structure and morphology, as well as a range of remarkable properties such as biological, chemical, electronic, and optical properties. In this work, different concentrations of MXene (M) were added to polyvinyl alcohol (PVA, P)/nano-hydroxyapatite (n-HA, H) mixed solution, and series of PVA/n-HA/MXene (PHM) composite membranes were obtained by combining sol-gel and freeze-drying processes. Morphology, chemical composition, surface, and mechanical properties of the prepared PHM membranes were characterized by various techniques. Subsequently, the swelling and degradation performances of the composite membranes were tested by swelling and degradation tests. In addition, in vitro studies like cell adhesion, cytotoxicity, proliferation, osteogenic differentiation, and antibacterial properties of MC3T3-E1 were also evaluated. The results showed that the addition of MXene could apparently improve the composite membranes' physicochemical properties, bioactivity, and osteogenic differentiation. Specially, PHM membrane had the best comprehensive properties when the concentration of MXene was set as 2.0% w/v. In a word, the addition of MXene has a positive effect on improving the mechanical properties, osteogenic induction, and antibacterial properties of PH composite membranes, and the prepared PHM composite membranes possess potential applications for guided bone regeneration. [Display omitted] [ABSTRACT FROM AUTHOR]

Heat consumption is a serious energy waste, especially in an extremely cold environment. In view of their excellent advantages, several kinds of aerogels with different functions were emerged successively and served as critical materials in various areas. In this contribution, a simple strategy was developed to fabricate a high-fidelity and high-performance organic/inorganic composite aerogel by integrating dianhydrid-end capped polyamide acid (PAA) precursor and multi-amino functionalized hydroxyapatite (m-AmHA; used as the inorganic cross-linkers) in different feed ratios. Followed by the freeze-drying and thermal imidization treatments, the chemical cross-linked polyimide (PI) and HA based aerogels (HA x @PI, in which x represents the percentage of HA content) were obtained. The synergistic effect of inorganic filler and microporous structure of aerogel led to a great improvement of mechanical and thermal properties. Most importantly, the resultant HA x @PI aerogels could maintain their excellent physicochemical properties in several extreme environments such as ultra hot (300 °C), extreme cold (-196 °C; liquid nitrogen), water soaking (2 h, 40 °C), acid (pH 2.0; 1 h, 40 °C) and alkali (pH 12.0; 1 h, 40 °C) conditions. Based on these outstanding properties, we believe that such HA x @PI composite aerogels with low cost and high performances endowed them to be an ideal candidate to be employed in several harsh environments in addition to the conventional insulation and flame-retardant materials. • Uniformity dispersed HA contained polyimide-based aerogels were fabricated. • The mechanical properties, flame resistance, and thermal insulation properties were enhanced with the doping of HA. • Such aerogels could withstand several harsh environments, including ultra hot, extreme cold, water soaking, acid and alkali conditions, without influence on their physicochemical properties. [ABSTRACT FROM AUTHOR]

The article discusses the resumption of conferences and meetings in the surface finishing industry following the Covid pandemic. It highlights recent events such as the 15th EDNANO workshop in France and the International Conference on Surface Engineering in South Korea. The article also mentions upcoming events, including the Interfinish Congress in Hong Kong. The current issue of the journal features articles on various topics related to surface finishing, such as electrochemical synthesis, hydroxyapatite coatings, and corrosion properties. The article concludes with an apology for a delay in the printing and mailing of the journal's March issue. [Extracted from the article]

There is a strong need to search for more effective compounds with bone anti-resorptive properties, which will cause fewer complications than commonly used bisphosphonates. To achieve this goal, it is necessary to search for new techniques to characterize the interactions between bone and drug. By studying their interaction with hydroxyapatite (HA), this study used three forms of ceramic materials, two of which are bone-stimulating materials, to assess the suitability of new active substances with anti-resorptive properties. In this study, three methods based on HA in loose form, polycaprolactone/HA (a polymer-ceramic materials containing HA), and polymer-ceramic monolithic in-needle extraction (MINE) device (a polymer inert skeleton), respectively, were used. The affinity of risedronate (a standard compound) and sixteen aminomethylenebisphosphonates (new compounds with potential antiresorptive properties) to HA was defined according to the above-mentioned methods. Ten monolithic materials based on 2-hydroxyethyl methacrylate/ethylene dimethacrylate are prepared and studied, of which one was selected for more-detailed further research. Simulated body fluids containing bisphosphonates were passed through the MINE device. In this way, sorption–desorption of bisphosphonates was evaluated using this MINE device. The paper presents the advantages and disadvantages of each technique and its suitability for assessing new active substances. All three methods allow for the selection of several compounds with potentially higher anti-resorptive properties than risedronate, in hope that it reflects their higher bone affinity and release ability. [Display omitted] • Three methods for assessing the suitability of new active substances with anti-resorptive properties. • Investigation of the interactions between antiresorptive drugs and hydroxyapatite. • Sorption and desorption of risedronate and sixteen aminomethylenebisphosphonates. [ABSTRACT FROM AUTHOR]

To improve the surface bioactivity of carbon/carbon composites, functionalized carbon nanotube-gelatin-Zn doped hydroxyapatite (FIC-GL-ZnH) composite coatings were fabricated on carbon/carbon composites by a combination method of chemical vapor deposition, soaking and electrochemical deposition method. The morphology, bonding strength and in-vitro bioactivity of composite coating were investigated. Results showed that the functionalized carbon nanotube-gelatin could not only bond with the carbon/carbon composite substrate tightly by in-situ grown mode but also provide a three-dimensional network structure for the infiltration of Zn doped hydroxyapatite. The FIC-GL-ZnH coating with spherical shape had excellent bonding strength, which was about 2.3 times higher than that obtained for Zn doped hydroxyapatite coating. In-vitro bioactivity test demonstrated that the FIC-GL-ZnH coating could induce the formation of bone-like apatite with particle shape, exhibiting good in-vitro bioactivity. It was suggested that the FIC-GL-ZnH coating might be an effective method to improve the surface bioactivity of carbon/carbon composites. [ABSTRACT FROM AUTHOR]

Orthopedic implants with heterogeneous porous structures were known as ideal bone osteointegration. This research introduced the selective laser melting (SLM), finite element analysis (FEA), and a hydrothermal process (HT) for manufacturing a three-level heterogeneous porous structure. The macroporous structure was designed via CAD and micropores were tuned via laser power regulation. A nano-size layer of hydroxyapatite crystals was coated by an HT process. The mechanical properties were reinforced via a core-shell structure with core reinforcement. The existence of micropores and nano-hydroxyapatite coating enhanced the in vitro proliferation of preosteoblasts and osteogenic cellular behaviors of rBMSCs. Thus, the three-level heterogeneous porous titanium implants could inspire researchers with potential clue of cyto-implant interaction mechanism, therefore building ideal orthopedic implants with accelerated osteointegration. Porous structures of titanium implants play an important role in bone tissue regeneration; The geometrical environment influence cell behaviour and bone tissue ingrowth in all macro-/micro-/nanoscale. In this study, a novel method to fabricate heterogeneous scaffolds and its macro-/micro-/nanoscopic structures were studied. A CAD model was used to obtain the macroscopic structure and the insufficient laser power was introduced for porous microstructure. Therefore, a layer of nano hydroxyapatite was coated via hydrothermal process. Cytoproliferation and cytodifferentiation results indicated that a integrity of regular/irregular, macro-/micro-/nanoscale porous structure had advance in recruiting stem cells and promoting differentiation. This research is beneficial to the development of bone implants with better bone regeneration ability. [Display omitted] [ABSTRACT FROM AUTHOR]

In the present paper, the removal of fluoride from drinking was investigated via adsorption technique, an important contaminant that could cause serious threat to human health. The challenge of this work is the scale-up from batch to continuous operation, including regeneration of the adsorbent, using a commercial hydroxyapatite, namely Fuorandel®. Adsorption Dynamic Intraparticle Model (ADIM) was used to describe the data collected in batch mode, obtaining important parameters to design a continuous adsorption column, such as: surface diffusivity, D S , and tortuosity, τ. Those parameters were fixed to simulate the experimental data collected in a continuous device obtaining good results. Finally, the sorbent regeneration in a batch system was investigated, optimizing the conditions to enhance Fluorandel® recovery. The present paper shows clearly the potential application of the selected sorbent, giving all the tools needed to scale-up the operation at industrial level. [Display omitted] • Fluoride was removed from ultrapure water using hydroxyapatite. • Experiments were collected both in batch and continuous devices. • Data were correctly interpreted using dynamic intraparticle model (ADIM). • Surface diffusivity and tortuosity factors were estimated on the data. • Fluoride adsorption was more efficient when testing mineral water. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Tissue engineering strives for innovative solutions in addressing challenges associated with contemporary bone tissue implants. This study focuses on the electrophoretic deposition (EPD) of hydroxyapatite-based bioceramic composites containing antibacterial agents onto titanium surfaces. Two composite coatings, hydroxyapatite/chitosan (HAP/CS) and hydroxyapatite/chitosan/gentamicin (HAP/CS/Gent) were developed to combat issues such as poor adhesion, limited antibacterial potential, limited bioactivity, and potential toxicity of implant materials. EXPERIMENTAL: EPD was performed at constant voltage (5 V, 12 min) on pure Ti plates from aqueous (HAP/CS and HAP/CS/Gent) suspensions. The uniformity and functionality of the deposited coatings were assessed through comprehensive physico-chemical characterization using X-ray diffraction (XRD) (Philips PW 1710, Netherlands) and scanning electron microscopy (SEM, Hitachi S-4700, J) equipped with energy dispersive X-Ray spectroscopy (EDS, X-Max, Oxford Instruments, UK). Antibacterial activity was evaluated against Staphylococcus aureus TL and Escherichia coli ATCC 25922 by quantitatively monitoring changes in the viable number of bacterial cells in suspension. Cytotoxicity against MRC-5 and L929 cell lines was investigated using trypan blue dye-exclusion test (DET) and MTT assay for assessing cell metabolic activity. Statistical significance was determined for antibacterial and cytotoxicity results by one-way analysis of variance (ANOVA), followed by multiple comparisons post-hoc test. RESULTS AND DISCUSSION: XRD revealed broadened diffraction maximums corresponding to fine HAP crystallites. Porous surface with homogeneously distributed spherical HAP agglomerates embedded in wax-like polymers' matrix of CS was observed for both coatings by SEM. The addition of gentamicin significantly enhanced the antibacterial activity of the HAP/CS/Gent coating – complete reduction of S. aureus bacterial cells was achieved within 1 h of exposure. MTT and DET tests indicated low cytotoxicity against MRC-5 and L929 tested cell line for both samples. Slightly decreased cell percentage viability due to gentamicin presence was observed for HAP/CS/Gent. CONCLUSIONS: Single-step EPD yielded antibacterial composite coatings with potential for biomedical applications. HAP/CS/Gent showed successful gentamicin loading, favorable crystalline structure, and strong antibacterial effects. The presence of fine HAP crystallites yielded a larger surface area, favorable for new bone growth and improved osseointegration. HAP/CS/Gent exhibited good antibacterial activity against both tested bacteria (especially pronounced against S. aureus – bactericidal effect), while preserving low cytotoxicity, indicating the high potential for biomedical applications. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Hydroxyapatite, the main inorganic component of human bone, is a widely used bioceramic for bone implant coatings due to its chemical and structural similarity with bone minerals and approved biocompatibility. Nowadays, the surface properties of implants are also modified by the addition of different biopolymers. Features such as biocompatibility, tuned biodegradability, and non-cytotoxicity make these materials excellent candidates for these applications. Zein is one of the natural polymers that has gained great interest for biomedical applications due to its natural renewable resource, biodegradability, biocompatibility and potential antibacterial activity. EXPERIMENTAL: In this study, zein/titanium dioxide (zein/TiO2), hydroxyapatite/zein/titanium dioxide (HAp/zein/TiO2) and strontium-doped hydroxyapatite/zein/titanium dioxide (Sr-HAp/zein/TiO2) coatings were obtained on a titanium substrate by in situ anodization/anaphoretic deposition method at a constant voltage of 60 V and deposition time of 1 min. For the fabrication of HAp/zein/TiO2 and Sr-HAp/zein/TiO2 composite coatings, HAp and SrHAp nano-sized powders obtained by a modified chemical precipitation method were used. The microstructure and morphology of all coatings were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Adhesion strength was measured according to the ASTM D3359-02 standard. Morphology and cell adhesion were analyzed by SEM. RESULTS AND DISCUSSION: The advantage of this methodological approach compared to cataphoretic deposition is reflected in the simultaneous performance of several processes. The first is the anodization of the substrate surface, whereby a passive oxide layer (TiO2) is formed on the surface, which changes the structure and increases the surface roughnessin a controlled manner. Another parallel process is the deposition of the HAp based coatings on the substrate. This way of coating formation shows better results than cataphoretic deposition in terms of better coating adhesion to the substrate. Adhesion strength was significantly improved compared to coatings obtained by cataphoretic processes, without the need for subsequent treatment. Cytotoxicity tests showed that there was no significant decrease in the survival of healthy human lung fibroblasts (MRC-5) cells exposed to the obtained coatings. CONCLUSIONS: Altogether, zein/TiO2, HAp/zein/TiO2 and Sr-HAp/zein/TiO2 could be promising non-toxic biomaterials for orthopedic and dental applications. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) is a non-bioceramic commonly used in human implants in the form of coatings, which are limited in their application by mechanical and wear resistance properties, as well as biodegradability. In this study, fluorine substituted hydroxyapatite (FHA) coatings were prepared on Ti–6Al–4V surfaces by plasma spraying method using a mixture of calcium fluoride and hydroxyapatite powders. The prepared coatings were characterized by X-ray diffraction and fourier transform infrared (FTIR) spectroscopy at different levels of calcium fluoride (3 wt%, 6 wt%, 9 wt%, and 12 wt%). The biocompatibility of the coatings was evaluated by in vitro mineralization experiments. Experimental results showed that at 9 wt% of calcium fluoride, the prepared FHA coatings had better mechanical properties, with improved bond strength (28.2 MPa). The X-ray diffraction patterns of the coatings reflect the fluorine substitution during the spraying process and the 9FHA has the highest crystallinity according to the XRD analysis, which is closely related to the biological activity of the coating. In addition, Potentiodynamic polarisation showed that the sample coated with the 9FHA coating had the highest Ecorr and lowest Icorr, indicating the best corrosion resistance. The FHA coating exhibits faster apatite deposition in simulated body fluid, and the efficiency of apatite deposition increases with the increase of CaF 2. [ABSTRACT FROM AUTHOR]

A self-helix structure Si3N4 nanobelts reinforced hydroxyapatite (HSN/HA) coating has been synthesised on carbon/carbon composites by a combination method of catalyst-assisted pyrolysis of polymeric precursors and electrochemical deposition. The morphology, microstructure, and bonding strength of the coating were analysed. An individual Si3N4 nanobelt showed a self-helical shape. The bonding strength between HSN/HA coating and carbon/carbon composites reached 12.5 ± 0.72 MPa, higher than that of pure HA coating (6.38 ± 0.32 MPa). HSN/HA coating has the potential to apply to hard tissue substitution surgery in the future. [ABSTRACT FROM AUTHOR]

• TiO 2 HA coating and TiO 2 HA-PCL hybrid coating were deposited on as-polished ZM21 alloy by dip-coating method. • An interconnected microporous layer of PCL layer was fabricated on TiO 2 HA-PCL coating. • The adhesion strength of TiO 2 HA-PCL hybrid coating was 1.5 times more than TiO 2 HA coating. • After immersion, TiO 2 HA-PCL hybrid coated sample was least degraded and the deposited apatite was richest in Ca/P ratio. • An uninterrupted passage of H 2 gas through micro-porosities did not cause any delamination. Surface modification for improving corrosion resistance of Mg alloys is highly demanded for degradable orthopedic and cardiovascular devices. The research reports the design and development of TiO 2 HA composite and novel TiO 2 HA–PCL hybrid coating belonging to the unique class of inorganic organic hybrid with striking features that are explored for the first time in the corrosion resistance of Mg alloys. Sol–gel dip coating combined with non-solvent induced phase separation is used to create the hybrid coating. TiO 2 HA–PCL hybrid coating introduces strong hydrogen bonding between TiO 2 HA inorganic matrix and PCL organic layer in addition to the Vander wall electrostatic interaction of the later with the Mg substrate which in turn enhance adhesion strength to about 1.5 times of TiO 2 HA coating. The corrosion potentials for TiO 2 HA–PCL and TiO 2 HA were found to be −0.407 V and −1.017 V (vs Ag/AgCl), respectively. The current densities of TiO 2 HA–PCL and TiO 2 HA were found to be 7.31 × 10−8 A/cm2 and 4.03 × 10−4 A/cm2 respectively. The corrosion resistance of coatings was confirmed by immersion testing by weight loss, pH changes and H 2 evolution measurements at interval of 7 days till 28 days. The present TiO 2 HA–PCL coating in comparison to TiO 2 HA coating demonstrate nearly 6% less weight loss. The outcome of the present work was compared with the similar coatings in recent past. The work done ingresses enhancing the corrosion resistance of Mg alloys, which fulfill the dreams of future degradable orthopedic and cardiovascular devices. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) alloys are receiving increasing attention as biodegradable implant materials in recent years. However, their low corrosion resistance and fast degradation in the physiological environment remain challenges for a widespread application. Hydroxyapatite (HA) coating on Mg alloys can enhance their corrosion resistance, biocompatibility, and bioactivity of the Mg alloy substrates since the compositions of HA are similar to those of the hard tissue of natural bone. This review analyzes the challenges of Mg alloys for biomedical applications, the fundamental requirements for biodegradable metals, and the corrosion mechanisms of Mg alloys in the physiological environment. The benefits of HA coatings on Mg alloys, the most commonly used surface coating techniques and their advantages and limitations, and the in vitro and in vivo performance of Mg alloys with and without surface coatings are comprehensively elucidated. Multistep processes such as alkali treatment and then HA coating by electrochemical deposition on Mg alloys appear to be necessary to achieve a satisfactory surface coating on Mg alloys, which has been demonstrated to have the potential to improve the degrading behavior, bioactivity and biocompatibility. Multifunctional coatings are most effective in achieving safe and bioactive Mg alloy surfaces for promising biodegradable implant applications. [ABSTRACT FROM AUTHOR]

A series of nanocomposite coatings was produced, comprising a hydrogel polymer, poly(2-hydroxyethyl methacrylate)/poly(ε-caprolactone) (PHEMA/PCL) matrix with nanoscale carbonated hydroxyapatite (nCHA) filler particles. The weight fraction of the filler was varied from 0 to 20% and the composites were applied as coatings onto Ti-6Al-4V substrates. The filler distribution and surface morphology were investigated by AFM, and the mechanical stability of the coatings was characterised using nanoindentation in both dry and wet conditions. The cellular response to the coatings was also examined in vitro using human osteoblast (HOB) cells. It was found that interfacial cracking occurred for composites containing greater than 10 wt.% nCHA and that 10 wt.% nCHA composite coatings appear to offer the greatest coating stability and bioactivity compared with the other composite coatings. It was concluded that the nCHA-containing PHEMA/PCL composite coatings had the potential to provide a soft, low modulus interface between metal implants and bone. [ABSTRACT FROM AUTHOR]

Bone and tooth enamel surface are made up of different crystallographically hydroxyapatite (HA), whereby bone comprises a(b)-planes of HA whilst tooth enamel comprises c-planes of HA. The reason behind the difference between HA orientations in both tissues are still yet to be discovered. We report the fabrication of anisotropic coatings of a-plane oriented HA according to the following process: (i) synthesis of a-plane oriented HA powders via a hydrothermal reaction and (ii) fabrication of a-plane oriented HA coatings via a Drop-on-Demand (DoD) micro-dispensing technique. Two types of HAs with high a-plane orientation degree of 72.2 and 75.6% (HA10 and HA84, respectively) was synthesised for the DoD coatings. The HA84 coating demonstrated more uniform and flatter surface than HA10 coating. The heat treatment of HA10 and HA84 coatings prepared with mesh-sieved particles led to a low adhesion strength for the substrates. However, the orientation degrees of those coatings (96.0 and 94.6%, respectively) were higher than the coatings without mesh-sieving. [ABSTRACT FROM AUTHOR]

Self-healing coatings have attracted attention on surface modification of magnesium alloys, as it can recover the barrier ability of the coatings from corrosion attack. Nevertheless, previous works on this aspect are not suitable for biomedical magnesium alloys owing to the lack of biocompatibility. In this study, we fabricated a self-healing coating on biomedical Mg-1Ca alloy by compositing silk fibroin and K 3 PO 4. PO 4 3− ions act as corrosion inhibitor, while K3+ ions help to regulate the secondary structures of silk fibroin. The scratch test, scanning vibrating electrode technique (SVET), and electrochemical impedance spectroscopy (EIS) provide comprehensive results, confirming the pH-sensitive self-healing capacity of the composite coating. Moreover, cells' (MC3T3-E1) multiple responses including spreading, adhesion, proliferation, and differentiation illustrate the preferable biocompatibility as well as the osteogenic activity of the coating. These primary findings might open new opportunities in the exploration of self-healing coatings on biomedical magnesium alloys. Biomedical magnesium alloys surface modifications have been studied for years, which however the biomedical self-healing coatings were rarely involved. In this work, silk fibroin and phosphate (K 3 PO 4) were composited to fabricate coating on biomedical magnesium alloys. The coating not only owned the self-healing ability with pH sensitivity, but also endowed the substrate preferable corrosion resistance as well as osteogenic activity. This work gives a new insight into surface modification for biomedical Mg alloys. [ABSTRACT FROM AUTHOR]

An effective treatment for peri-implantitis is to completely remove all the bacterial deposits from the contaminated implants, especially the organic residues, to regain biocompatibility and re-osseointegration, but none of the conventional decontamination treatments has achieve this goal. The photocatalytic activity of TiO 2 coating on titanium implants to degrade organic contaminants has attracted researchers' attention recently. But a pure TiO 2 coating only responses to harmful ultraviolet light. Additionally, the poor coating mechanical properties are unable to protect the coating integrity versus initial mechanical decontamination. To address these issues, a unique TiO 2 nanoceramic coating was fabricated on titanium substrates through an innovative plasma electrolytic oxidation (PEO) based procedure, which showed a disordered layer with oxygen vacancies on the outmost part. As a result, the coating could decompose methylene blue, rhodamine B, and pre-adsorbed lipopolysaccharide (LPS) under visible light. Additionally, the coating showed two-fold higher hardness than untreated titanium and excellent wear resistance against steel decontamination instruments, which could be attributed to the specific micro-structure, including the densely packed nanocrystals and good metallurgical combination. Moreover, the in vitro response of MG63 cells confirmed that the coating had comparable biocompatibility and osteoconductivity to untreated titanium substrates. This study provides a unique coating technique as well as a photocatalytic cleaning strategy to enhance decontamination of titanium dental implants, which will favour the development of peri-implantitis treatments. The treatment of peri-implantitis is based on the complete removal of bacterial deposits, especially the organic residues, but conventional decontamination treatments are hard to achieve it. The photocatalytic activity of TiO 2 coating on titanium implants to degrade organic contaminants provides a promising strategy for deeper decontamination, but its nonactivation to visible light and poor mechanical properties have limited its application. To address these issues, a unique TiO 2 nanoceramic coating was fabricated on titanium substrates based on plasma electrolytic oxidation. The coating showed enhanced visible-light photocatalytic activity, excellent wear resistance and satisfied biocompatibility. Based on this functional coating, it is promising to develop a more efficient strategy for deep decontamination of implant surface, which will favour the development of peri-implantitis treatments. [ABSTRACT FROM AUTHOR]

Peri-implantitis is the most common risk factor for dental implant failure. Nanostructured ceria (nano-CeO 2) has anti-inflammatory and antibacterial functions, and different shapes of ceria enclosed by specific crystal planes could be an effective approach to enhance intrinsic catalysis. In the present study, the authors developed a novel implant surface-modification strategy by coating different shapes of nano-CeO 2 onto titanium (Ti) surfaces to enhance their antibacterial and anti-inflammatory properties. The objectives of the study were to: (1) develop novel Ti surfaces modified with different shapes of nano-CeO 2 (nanorod, nanocube and nano-octahedron) for peri-implantitis prevention; (2) investigate and compare the inhibition efficacy of different shapes of CeO 2 -modified surfaces against biofilms of peri-implantitis-related pathogens; and (3) evaluate the different CeO 2 -modified surfaces on cell inflammatory response in vitro and in vivo. The results showed that nanorod CeO 2 -modified Ti had more bacteria attachment of Streptococcus sanguinis in the early stage, compared with other CeO 2 -modified Ti (p < 0.05). They all exhibited similarly substantial CFU reductions against peri-implantitis-related biofilms (p > 0.1). Nanocube and nano-octahedron CeO 2 -modified Ti exerted much better anti-inflammatory effects and ROS-scavenging ability than nanorod CeO 2 in vitro (p < 0.05). In vivo , the mean mRNA expression of TNF-α, IL-6 and IL-1β in the tissues around Ti was decreased by the three shapes of nano-CeO 2 ; nano-octahedron CeO 2 showed the strongest anti-inflammatory effect among all groups (p < 0.05). In conclusion, all three types of CeO 2 -modified Ti exerted equally strong antibacterial properties; nano-octahedron CeO 2 -modified Ti had the best anti-inflammatory effect. Therefore, CeO 2 -modified Ti surfaces are highly promising for enhancing antimicrobial functions for dental implants. Novel nano-octahedron CeO 2 coating on Ti had great therapeutic potential for alleviating and eliminating peri-implantitis. Peri-implantitis is the most common risk factor for dental implant failure. Nanostructured ceria (nano-CeO 2) has anti-inflammatory and antibacterial functions, and different shapes of ceria enclosed by specific crystal planes could be an effective approach to enhance intrinsic catalysis. In the present study, we developed a novel implant surface-modification strategy by coating different shapes of nano-CeO 2 onto titanium surfaces to enhance their antibacterial and anti-inflammatory properties for dental implants. In addition, we found that the nano-octahedron CeO 2 coating on titanium would have great therapeutic potential for alleviating and eliminating peri-implantitis. [ABSTRACT FROM AUTHOR]

In this study, we explored a ternary dopant system utilizing 0.25 wt% ZnO to induce osteogenesis, 0.5 wt% SiO 2 to induce angiogenesis, and 2.0 wt% Ag 2 O to provide secondary infection control within a plasma assisted hydroxyapatite coating for orthopaedic or dental applications. The objective of this study was to understand the effects of ZnO, SiO 2 , and Ag 2 O dopants on the mechanical and biological properties of hydroxyapatite (HA) coatings on titanium (Ti). Coatings were deposited using a 30 kW plasma spray system equipped with a supersonic nozzle to produce above standard coating bond strengths of 24 ± 2 MPa on Ti6Al4V and 22 ± 1 MPa on commercially pure Ti substrates. Antibacterial properties were revealed in vitro against E. coli and S. aureus. The ternary dopant system was implanted in 18 male Sprague-Dawley rats with timepoints of 5 and 10 weeks. By week 5, ZnSiAg-HA produced 32% bone mineralization of 68% total bone formation compared to only 11% bone mineralization of 55% total bone formation in the undoped coating. This system can be employed for replacement surgeries and revision surgeries to reduce healing time and enhance osseointegration. Total hip replacements increased 124% from 2000 to 2010 with an ever-increasing rate due to the rise in average life span and an escalation in surgeries for young patients. Replacement surgeries come with the risk of rejection, poor integration, and infection. This study incorporates biologically relevant metallic oxides of ZnO, SiO 2 , and Ag 2 O within a hydroxyapatite coating on titanium deposited using a radio frequency induction plasma spray. A ternary dopant system has not been explored in the current literature and little is known about these particular dopants in vivo. This proposed system can be employed for replacement surgeries to lower healing time and enhance osseointegration between implant and host tissue. [ABSTRACT FROM AUTHOR]

Using magnetic nanoparticles to remove the dispersed oil from produced water is a promising way to overcome the difficulties faced by current treatment technologies. Therefore, in this study, novel ZnFe 2 O 4 -hydroxyapatite core-shell nanocomposites (ZFHA) was prepared by precipitation method and investigated as an adsorbent to remove residual oil from produced wastewater. The prepared ZFHA nanocomposites were studied by FTIR, X-ray diffraction, HRTEM, SAED, and EDX. The results revealed that hydroxyapatite was coated on the ZnFe 2 O 4 surface and formed a core-shell structure. The effect of various parameters on oil adsorption process like bed height (59, 118 and 178 mm), flow rate (1, 3 and 5 mL min−1), effect of temperature 25–77 °C, initial oil concentration (100, 500, 1000 and 10,000 ppm) and pH (2–10) were investigated. The experimental data showed that with increased column bed depth from 59 to 178 mm, breakpoint time (t b) increased from 30 to 48 min. The highest equilibrium adsorption capacity of oil at optimum conditions (77 °C, 10,000 ppm, 3 mL/min and 178 mm) were estimated to be 3500 mg L−1. The contact time decreased with the increase of bed height and flow rate. Adsorption kinetic was evaluated in a fixed bed column. Finally, the regeneration of the exhausted ZFHA adsorbent was assessed; which revealed satisfactory results for three times reusability after saturation. Therefore; ZFHA could be applied effectively for adsorption of residual oil from synthesis oily wastewater samples prepared from produced water of Egyptian fields of the petroleum industry. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Coatings based on ion-substituted calcium phosphate (Ca-P) have attracted great attention in the scientific community over the past decade for the development of biomedical applications. Among such Ca-P based structures, hydroxyapatite (HA) has shown significant influence on cell behaviors including cell proliferation, adhesion, and differentiation. These cell behaviors determine the osseointegration between the implant and host bone and the biocompatibility of implants. This review presents a critical analysis on the physical vapor deposition magnetron sputtering (PVDMS) technique that has been used for ion-substituted Ca-P based coatings on implants materials. The effect of PVDMS processing parameters such as discharge power, bias voltage, deposition time, substrate temperature, and post-heat treatment on the surface properties of ion-substituted Ca-P coatings is elucidated. Moreover, the advantages, short comings and future research directions of Ca-P coatings by PVDMS have been comprehensively analyzed. It is revealed that the topography and surface chemistry of amorphous HA coatings influence the cell behavior, and ion-substituted HA coatings significantly increase cell attachment but may result in a cytotoxic effect that reduces the growth of the cells attached to the coating surface areas. Meanwhile, low-crystalline HA coatings exhibit lower rates of osteogenic cell proliferation as compared to highly crystalline HA coatings developed on Ti based surfaces. PVDMS allows a close reproduction of bioapatite characteristics with high adhesion strength and substitution of therapeutic ions. It can also be used for processing nanostructured Ca-P coatings on polymeric biomaterials and biodegradable metals and alloys with enhanced corrosion resistance and biocompatibility. Statement of Significance Recent studies have utilized the physical vapor deposition magnetron sputtering (PVDMS) for the deposition of Ca-P and ion-substituted Ca-P thin film coatings on orthopedic and dental implants. This review explains the effect of PVDMS processing parameters, such as discharge power, bias voltage, deposition time, substrate temperature, and post-heat treatment, on the surface morphology and crystal structure of ion-substituted Ca-P and ion-substituted Ca-P thin coatings. It is revealed that coating thickness, surface morphology and crystal structure of ion-substituted Ca-P coatings via PVDMS directly affect the biocompatibility and cell responses of such structures. The cell responses determine the osseointegration between the implant and host bone and eventually the success of the implants. [ABSTRACT FROM AUTHOR]

To improve initial osteoblast adhesion and subsequent osseointegration, TiO2 nanotubes layer was constructed on the titanium (Ti) surface by anodic oxidation (AO), with an additional hydroxyapatite (HA) coating to form the AO/HA surface. Tests on in vitro cellular activity displayed that the AO surface, especially the AO/HA surface, promoted initial adhesion, proliferation and differentiation of osteoblast cells. The modified AO and AO/HA surfaces further presented an up-regulated gene expression of osteogenic and adhesion markers collagen type 1 (COL), osteopontin (OPN), osteocalcin (OCN) and vinculin. In addition, in vivo experiments with a rat model demonstrated that the AO surface, particularly the AO/HA surface, achieved earlier osseointegration and a superior bone bonding ability compared with Ti. Our study shed light on a synergistic role played by nanotopography and HA in promoting osteoblast adhesion, proliferation, differentiation and osseointegration, thus suggesting a promising method for better modifying the implant surface. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Plasma sprayed hydroxyapatite (HA) coating is known to improve the osteoconductivity of metallic implants. However, the adhesive bond strength of the coating is affected due to a mismatch in coefficients of thermal expansion (CTE) between the metal and HA ceramic. In this study, a gradient HA coating was prepared on Ti6Al4V by laser engineered net shaping (LENS™) followed by plasma spray deposition. In addition, 1 wt% MgO and 2 wt% Ag 2 O were mixed with HA to improve the biological and antibacterial properties of the coated implant. Results showed that the presence of an interfacial layer by LENS™ enhanced adhesive bond strength from 26 ± 2 MPa for just plasma spray coating to 39 ± 4 MPa for LENS™ and plasma spray coatings. Presence of MgO and Ag 2 O did not influence the adhesive bond strength. Also, Ag+ ions release dropped by 70% less with a gradient HA LENS™ layer due to enhanced crystallization of the HA layer. In vitro human osteoblast cell culture revealed presence of Ag 2 O had no deleterious effect on proliferation and differentiation when compared to pure HA as control and provided antibacterial properties against E. coli and S. aureus bacterial strands. This study presents an innovative way to improve interfacial mechanical and antibacterial properties of plasma sprayed HA coating for load-bearing orthopedic as well as dental implants. Statement of significance Implants are commonly composed of metals that lack osteoconductivity. Osteoconductivity is a property where bone grows on the surface meaning the material is compatible with the surrounding bone tissue. Plasma sprayed hydroxyapatite (HA) coating improves the osteoconductivity of metallic implants, however, the adhesive bond strength can be weak. This study incorporates a gradient HA coating by using an additive manufacturing technique, laser engineered net shaping (LENS™), followed by plasma spray deposition to enhance the adhesive bond strength by incorporating a thermal barrier. The proposed system has not been well studied in the current literature and the results presented bring forth an innovative way to improve the interfacial mechanical and antibacterial properties of plasma sprayed HA coating for load-bearing orthopedic implants. [ABSTRACT FROM AUTHOR]

In the present work, we test four thin coatings for titanium implants, namely, bioglass, GB14, Beta-Tricalciumphosphate (β-TCP) and hydroxyapatite (HA) with and without incorporated copper ions for their osteointegrative capacity. A rabbit drill hole model for time intervals up to 24 weeks was used in this study. Implant fixation was evaluated by measuring shear strength of the implant/bone interface. Quantitative histological analysis was performed for the measurements of bone contact area. Implants with and without copper ions were compared after 24 weeks. Thin coatings of GB14, HA or TCP on titanium implants demonstrated high shear strength during the entire test period of up to 24 weeks. Results confirmed osteointegrative properties of the coatings and did not reveal any negative effect of copper ions on osteointegration. The integration of copper in degradable osteoconductive coatings with a thickness of approx. 20 μm represents a promising method of achieving antibacterial shielding during the entire period of bone healing while at the same time improving osteointegration of the implants. [ABSTRACT FROM AUTHOR]

To improve the bone healing efficiency of porous titanium implants, desired biological properties of implants are mandatory, involving bioactivity, osteoconductivity, osteoinductivity and a stable environment. In this study, bare porous titanium (abbr. pTi) with the porosity of 70% was fabricated by vacuum diffusion bonding of titanium meshes. Hydroxyapatite-coated pTi (abbr. Hap-pTi) was obtained by successively subjecting pTi to alkali heat treatment, pre-calcification and simulated body fluid. Both pTi and Hap-pTi were respectively implanted into the tibia defect model (ϕ10 mm × 6 mm) in New Zealand white rabbits, then subjected to non-invasively axial compressive loads at high-magnitude low-frequency (HMLF), which were denoted as F-pTi and F-Hap-pTi, respectively. Bone repairing efficiencies were analyzed by postoperative X-ray examination, optical observation and HE staining after 14 and 30 days of implantation. ALP and OCN contents in serum were also examined at 30 days. Results showed that the sham group and sham group with mechanical stimulation (abbr. F-sham) preferably caused bone fractures. Qualitatively, Hap-pTi reduced the risk of bone fractures and enhanced bone healing slightly more effectively compared to bared pTi. However, both Hap-pTi combined with mechanical stimulation and F-pTi in the case of bioactive modification could result in a higher bone healing efficiency (F-Hap-pTi). The molecular signaling investigation of ALP and OCN contents in serum further revealed a probable synergistic effect of Hap coating coupling with HMLF compression on improving bone repairing efficiency. It provides a candidate of clinically applicable therapy for osseous defects. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Surface functionalization of teeth with fluoride-incorporated apatite layers displays great potential in treatments and prevention of dental disorders. In this study, we used a sintered hydroxyapatite (sHA) substrate as a model material of teeth, and established a rapid and area-specific coating technique of fluoride-incorporated apatite layers by using a laser-assisted biomimetic (LAB) process. In this technique, a sHA substrate was irradiated on the surface with a Nd:YAG pulsed UV laser for 30 min in supersaturated calcium phosphate (CaP) solutions with various fluoride concentrations. The fluoride concentration in the CaP solution was varied to control morphology, crystalline structure, and fluoride content of the resulting layers. Without fluoride in the CaP solution, an octacalcium phosphate (OCP) layer with a flake-like structure was formed on the laser-irradiated surface of the substrate. The addition of fluoride (1000 µM and 3000 µM) to the CaP solution led to the formation of fluoride-incorporated apatite layers with an enamel-like needle-like nanostructure. The fluoride-incorporated apatite layers adhered firmly to the sHA surface and reduced acid dissolution of the sHA substrate by acting as a protective covering. Additionally, the layers released fluoride ions for more than 24 h, and exhibited antibacterial activity relative to a caries-causing bacterium, namely Streptococcus mutans. Thus, our LAB process can potentially act as a new tool for functionalization of tooth surfaces. Statement of Significance We used a sintered hydroxyapatite (sHA) substrate as a model material of teeth, and established a rapid and area-specific coating technique of fluoride-incorporated apatite layers on the sHA surface by using our laser-assisted biomimetic (LAB) process. In this process, pulsed laser was utilized to accelerate seeded crystal growth in supersaturated calcium phosphate solutions supplemented with NaF. The thus-fabricated fluoride-incorporated apatite layers consisted of enamel-like needle-like nanocrystals with c -axis orientation. These fluoride-incorporated apatite layers adhered firmly to the sHA surface, reduced acid dissolution of the sHA substrate by acting as a protective covering, and exhibited antibacterial activity against Streptococcus mutans through the fluoride release. Thus, our LAB process can potentially act as a new tool for functionalization of tooth surfaces. [ABSTRACT FROM AUTHOR]

In the present study, reinforced hydroxyapatite (HA) coatings (HA + 10 wt% Al 2 O 3 and HA + 10 wt% ZrO 2 ) were deposited on SS-316 L substrate with an intermediate layer (bond coat) of zirconia by vacuum plasma spray technique. The so-formed reinforced HA coatings were heat treated at 700 °C for 1 h. The influence of post coating heat treatment on phase composition, microstructure, mechanical and electrochemical corrosion properties were investigated. As-sprayed and heat treated coatings were characterized by x-ray diffraction, scanning electron microscope, surface roughness, porosity and crystallinity. Results showed that after post coating heat treatment, the structural integrity of HA has been completely re-established. Moreover, significant drop in porosity has been observed due to the sintering effect produced by heat treatment. Considerable improvement in nanohardness and shear strength was witnessed; however, the nanohardness of top layer was decreased after annealing due to the weak bonding of partially melted and un-melted particles with fully melted splats caused by diffusion process. As-sprayed coatings exhibited higher wear resistance compared to heat treated coatings. Nevertheless, post coating heat treatment effectively enhanced the corrosion resistance of coatings, since, the heat treatment lead to densification of coatings microstructure which further reduces the active sites for dissolution. [ABSTRACT FROM AUTHOR]

Coating materials applied for intraosseous implants must be optimized to stimulate osseointegration. Osseointegration is a temporal and spatial physiological process that not only requires interactions between osteogenesis and angiogenesis but also necessitates a favorable immune microenvironment. It is now well-documented that hierarchical nano-micro surface structures promote the long-term stability of implants, the interactions between nano-micro structure and the immune response are largely unknown. Here, we report the effects of microporous titanium (Ti) surfaces coated with nano-hydroxyapatite (HA) produced by micro-arc oxidation and steam-hydrothermal treatment (SHT) on multiple cell behavior and osseointegration. By altering the processing time of SHT it was possible to shift HA structures from nano-particles to nano-rods on the microporous Ti surfaces. Ti surfaces coated with HA nano-particles were found to modulate the inflammatory response resulting in an osteoimmune microenvironment more favorable for osteo-/angio-genesis, most likely via the activation of certain key signaling pathways (TGF-β, OPG/RANKL, and VEGF). By contrast, Ti surfaces coated with nano-rod shaped HA particles had a negative impact on osteo-/angio-genesis and osteoimmunomodulation. In vivo results further demonstrated that Ti implant surfaces decorated with HA nano-particles can stimulate new bone formation and osseointegration with enhanced interaction between osteocytes and implant surfaces. This study demonstrated that Ti implants with micro-surfaces coated with nano-particle shaped HA have a positive impact on osseointegration. Statement of Significance Osteo-/angio-genesis are of importance during osteointegration of the implants. Recent advances unravel that immune response of macrophages and its manipulated osteoimmunomodulation also exerts a pivotal role to determine the fate of the implant. Surface nano-micro modification has evidenced to be efficient to influence osteogenesis, however, little is known links nano-microstructured surface to immune response, as well the osteoimmunomodulation. This study demonstrates that the nano-particles decorated micro-surface, compared with the nano-rods decorated micro-surface enables osteogenesis and angiogenesis concurrently that has not been investigated previously. This study also unravels that the immune response of macrophages can be manipulated by the nano-micro surface, especially the nano-dimension matters, leading to a differential effect on osteointegration. The additional knowledge obtained from this study may provide foundation and reference for future design of the coating materials for implantable materials. [ABSTRACT FROM AUTHOR]

Biomedical implants such as dental and orthopedic implants fails due to poor mechanical and biological properties. In order to solve this problem, Electron beam (e-beam) evaporations is used as one of the methods to deposit the hydroxyapatite (HA) on Ti-13Nb-13Zr (near β titanium alloy) and the coated implant may play a significant role in increasing the mechanical and biological properties. In the present study, Ti-13Nb-13Zr was coated with hydroxyapatite (HA) by e-beam evaporation technique. The coated alloys were morphologically analyzed by FESEM and AFM, and it demonstrates that there is an increase in the growth of calcium phosphate layer. In-vitro corrosion behavior of the coated and uncoated titanium alloys were performed by electrochemical impedance spectroscopy (EIS) studies in simulated body fluid solution. The results show that the corrosion resistance of the hydroxyapatite-coated alloy higher than that of the uncoated alloys and it evident that the HA-coated alloy have better corrosion protection for the implant application. The bioactivity of the HA-coated composites were evaluated by Hanks’ solution immersed them for seven days. The ratio Ca/P was increased gradually after soaking it for seven days. The cell viability results indicates that HA coated alloys support increase in the Osseo integration and it can be used for bone implant application. [ABSTRACT FROM AUTHOR]