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ABSTRACT Aim Methods Results Conclusions This nationwide population‐based cohort study aimed to assess the incidence of implant complication treatments, including implant removal procedures and peri‐implantitis treatments, in relation to implant surfaces and abutment types.Data from the National Health Insurance Service, covering approximately 50 million individuals, were used. Implants and abutments were categorized by codes, including surfaces such as resorbable blasting media, sandblasted large grit and acid‐etched (SA) and hydroxyapatite coating, along with abutment structures (one‐piece straight, two‐piece straight, angled). The incidence of implant complication treatments was analysed using Kaplan–Meier curves and Cox proportional hazards regression (α = 0.05).The study included 2,354,706 implants. The SA group had the lowest hazard ratio for implant removal procedures (p < 0.0001). No significant differences were found in the risk of peri‐implantitis treatments between implant surfaces (p = 0.0587). The risk of implant complication treatments did not differ significantly by the abutment type (p = 0.9542). The incidence rate of implant complication treatments was < 3.9 per 1000 implant‐years across all groups.The SA group showed a slightly lower risk of late implant loss, whereas no significant association was found for the abutment type groups. All implant and abutment type groups showed an incidence rate of < 3.9 per 1000 implant‐years for complication treatments. [ABSTRACT FROM AUTHOR]

The suboptimal ionic conductivity of commercial polyolefin separators exacerbates uncontrolled lithium dendrite formation, deteriorating lithium metal battery performance and posing safety hazards. To address this challenge, a novel organic‐inorganic composite separator designed is prepared to enhance ion transport and effectively suppress dendrite growth. This separator features a thermally stable, highly porous poly(m‐phenylene isophthalamide) (PMIA) electrospun membrane, coated with ultralong hydroxyapatite (HAP) nanowires that promote “ion flow redistribution.” The synergistic effects of the nitrogen atoms in PMIA and the hydroxyl groups in HAP hinder anion transport while facilitating efficient Li+ conduction. Meanwhile, the optimized unilateral pore structure ensures uniform ion transport. These results show that the 19 µm‐thick HAP/PMIA composite separator achieves remarkable ionic conductivity (0.68 mS cm−1) and a high lithium‐ion transference number (0.51). Lithium symmetric cells using HAP/PMIA separators exhibit a lifespan exceeding 1000 h with low polarization, significantly outperforming commercial polypropylene separators. Furthermore, this separator enables LiFePO4||Li cells to achieve an enhanced retention of 97.3% after 200 cycles at 1 C and demonstrates impressive rate capability with a discharge capacity of 72.7 mAh g−1 at 15 C. [ABSTRACT FROM AUTHOR]

Periosteal expansion osteogenesis (PEO) is a technique for augmenting bone by creating a gradual separation between the bone and periosteum. This study assessed PEO‐induced bone formation around the femurs of rats using a dynamic frame device (DFD), consisting of a shape memory membrane made of polyethylene terephthalate (PET) formed into a tubular shape. The DFDs, consisting of a PET membrane coated with hydroxyapatite (HA)/gelatin on the bone‐contact surface, were inserted between the periosteum and bone of the femurs of rats. In the experimental group, DFDs were suture‐fixed to the femur with 4–0 Vicryl Rapid; in the control group, 4–0 silk thread was used for fixation. Five rats per group were euthanized at intervals of 3, 5, and 8 weeks postoperatively. Bone formation was evaluated via micro‐CT imaging, histomorphometry, and histological analysis. Morphological analysis revealed new bone between the femur and the periosteum, expanded by the DFD, in all groups. The mean values of new bone were 0.30 mm2 proximally, 0.18 mm2 centrally, and 0.82 mm2 distally in the control group, compared to 1.05 mm2 proximally, 0.27 mm2 centrally, and 0.84 mm2 distally in the experimental group. A significant difference in new bone was observed in the proximal region of the experimental group. Histological examination showed that a single layer of newly formed neoplastic bone was noted on the cortical bone surface across all sites. The proximal portion displayed a bone marrow cavity at the center, encircled by a thick bone cortex with a layered structure. New bone formation was notable between existing cortical bone and the periosteum, particularly at both ends of the DFD. The use of PET in PEO was a viable option for achieving ideal bone morphology. [ABSTRACT FROM AUTHOR]

Background: Periosteal expansion (PEO) results in the formation of new bone in the space created between existing bone by expanding the periosteum. PEO has already been performed on rabbit parietal bone and effective new bone formation has been demonstrated. In this study, the utility of a polyethylene terephthalate (PET) membrane as an activator was evaluated in the more complex morphology of the mandible. Methods: A PET membrane coated with hydroxyapatite (HA)/gelatine was placed in the rabbit mandibular bone at lower margin of mandibular molar region underneath periosteum, and screw‐fixed. In the experimental group, the membrane was bent and screw‐fixed along the lateral surface of the bone, with removal of the outer screw after 7 days followed by activation of the membrane. The experimental group was divided into two subgroups: with and without a waiting period for activation. Three animals were euthanized at 3 weeks and another three at 5 weeks postoperatively. Bone formation was assessed using micro‐CT as well as histomorphometric and histological methods. Results: No PET membrane‐related complications were observed. The area of newly formed bone and the percentage of new bone in the space created by the stretched periosteum did not significantly differ between the control and experimental groups. However, in the experimental group a greater volume was present after 5 weeks than after 3 weeks. Histologically, bone formation occurred close to the site of cortical bone perforation, with many sinusoidal vessels extending through the perforations in the new bone into the overlying fibrous tissue. Inflammatory cells were not seen in the bone. [ABSTRACT FROM AUTHOR]

To investigate the reinforcing effect of nanoflower‐like hydroxyapatite (NFHA) in resin‐based dental composites, we synthesized a novel NFHA using microwave irradiation (MW), hydrothermal treatment (HT), and sonochemical synthesis (SS). Silanized NFHA was then used as the reinforcing filler in dental resin composites. We characterized the structure and morphology of various HA nanostructures using x‐ray diffraction, scanning electron microscope, and TEM. The mechanical performance of dental resin composites reinforced with silanized NFHA was measured using a universal testing machine. Spherical HA, synthesized through chemical precipitation (CP), served as the control group. One‐way analysis of variance was employed for the statistical analysis of the acquired data. The results demonstrate that the nanoflower morphology significantly was improved mechanical and physical properties. After conducting trials, the NFHA synthesized using MW and HT showed a substantial enhancement in mechanical and physical properties compared to the other structures. Therefore, it can be concluded that NFHA can serve as a novel reinforcing HA filler, providing regenerative properties to resin composites with sufficient mechanical strength. [ABSTRACT FROM AUTHOR]

Bone tissue engineering (BTE) is a biomedical area that develops scaffolds capable of mimicking and repairing damage on bone tissue. For this, a popular and nonexpensive 3D printing technique named fused deposition modeling (FDM) has been used. The potential use of 3D scaffolds of poly(butylene adipate-co-terephthalate (PBAT) has been investigated in BTE since this polymer presents good biocompatibility and degradability, as well as mechanical properties like those offered by the natural bone. A single material does not have the features to promote cell adhesion, proliferation, and differentiation; the incorporation of bioactive substances can overcome this issue. This work aimed to develop 3D printed PBAT scaffolds by FDM technique and coated them with hydroxyapatite (H), bioglass (B), and gelatin (G) by solution immersion technique to obtain a functional biomaterial to be applied on the BTE. Structural characteristics and morphological and mechanical properties of the 3D scaffolds were evaluated. The cell proliferation and mineralization of pre-osteoblastic cells (MC3T3-E1) were accessed by methylthiazolyldiphenyl-tetrazolium bromide, sulphorodhamine B, and Alizarin red assay, respectively. 3D printed PBAT scaffolds were successfully obtained by FDM, and the surface modification of 3D PBAT was proven through the changes observed in structural and morphological characteristics. In addition, the mechanical properties were improved in the modified scaffolds. Also, the coated 3D PBAT scaffolds with any bioactive substance increased and promoted cell proliferation and pre-osteoblastic differentiation. Therefore, the combination of 3D PBAT scaffolds and H, G, and/or B (doped with niobium) is an alternative to produce functional biomaterials for BTE. [ABSTRACT FROM AUTHOR]

To effectively combat infectious osteoporosis, Ti‐based implants with enhanced antibacterial and osseointegrative properties are urgently required. Herein, a one‐step method involving Mg thermal‐reduction is employed to modify a hydroxyapatite (HA) array on Ti, which comprises an inner TiO2 layer and an outer nanorod‐like HA layer. This process introduces oxygen vacancies (OVs) into the TiO2 layer and deposits a Mg─O‐contained amorphous nanolayer on each HA nanorod. The introduced OVs enhance reactive oxygen species (ROS) yield by the array during ultrasound treatment via narrowing TiO2 bandgap and improving H2O molecules absorption. The produced ROS, combined with a weak alkaline microenvironment created by the degraded Mg─O nanolayer, endows the array with potent bacterial‐killing and biofilm‐eradicating efficacies within a 5 min ultrasound treatment via the combination of proton‐consumption and cell envelop‐detriment effects. Moreover, due to the alkaline microenvironment and the released Mg2+, the array hinders osteoclastogenesis by activating the inflammation‐related FAK‐PI3K‐AKT signaling pathway in macrophages, as revealed by transcriptomic analysis, resulting in robust osseointegration in rat femoral shaft with concurrent bacterial‐infection and osteoporosis. This work paves a new way for simultaneously endowing a sonosensitive coating on Ti with sonodynamic treatment‐derived high antibacterial ability and alkaline microenvironment‐mediated strong osseointegration for infectious osteoporosis treatment. [ABSTRACT FROM AUTHOR]

Herein, polydimethylsiloxane (PDMS) surfaces are coated with hydroxyapatite (HA) using immobilization and biomineralization techniques with the aid of small molecules, namely, l‐aspartic acid (AA), l‐glutamic acid, and citric acid, in an effort to develop biointeractive surfaces for bone tissue‐related research. The efficacy of biomineralization and immobilization techniques and the impact of small molecules on HA deposition on PDMS surfaces are investigated by chemical and morphological analysis of surfaces, besides in vitro cell culture studies. Characteristic peaks of phosphate groups at wavelengths of 569 and 603 cm−1 in Fourier transform infrared spectroscopy analysis and HA's characteristic patterns identified at 26.1°, 31.7°, and 45.5° in X‐ray diffraction analysis demonstrate the successful deposition of HA particles on PDMS surfaces which are also observed on scanning electron microscopy micrographs. The interaction of human fetal osteoblast cells (hFOB 1.19) with HA‐deposited PDMS surfaces is evaluated with in vitro cell culture studies, which reveals increased cell metabolic activity and growth across all groups as compared to plain PDMS, with HA deposited on AA‐PDMS surfaces through biomineralization being the most stimulating group. Overall, small‐molecule effect on deposition of HA on PDMS substrates merits further investigation, particularly on substrates mimicking bone surface chemical and morphological features. [ABSTRACT FROM AUTHOR]

One of the main targets in modern dentistry is the prevention of caries. Not only daily nutrition plays an important role, but also the so‐called "pellicle" on the outer surface of teeth, which is mainly formed by saliva proteins. Moreover, numerous bacteria are part of this pellicle, which might cause caries by acidic metabolites. In the here‐presented study, a method for electrophoretic deposition (EPD) of hydroxyapatite (HAP) nanoparticles on gold surfaces, suitable for surface plasmon resonance (SPR) measurements, is developed. An "artificial tooth" is created and loaded by natural saliva in different concentrations (to form a natural pellicle), while the influence of an environment with different pH values has been studied. It could be demonstrated that even slight acid solutions damage the pellicle significantly within seconds, exposing the HAP to acidic degradation, which would lead to caries in the human oral cavities. This model allows to study pellicle formation as well as degradation in real time. As a practical example, the influence of beverages on the pellicle could be demonstrated. [ABSTRACT FROM AUTHOR]

In order to solve the problem of excessive degradation rate and insufficient biocompatibility of magnesium‐based bone implants, a polyphenol (EGCG) induced hydroxyapatite (HA) coating was prepared on the surface of AZ31 alloy. The physical and chemical properties and corrosion resistance of the coating were analysed in depth, and its biocompatibility was preliminarily explored in vitro. The results showed that the polyphenol (EGCG) conversion coating constructed on the AZ31 could successfully induce the formation of HA by complexing the phenolic hydroxyl group with calcium ions. The electrochemical and long‐term immersion experiments showed that the corrosion resistance of EGCG/HA composite coating was significantly improved. The self‐corrosion current density, hydrogen evolution and the increase of pH value of AZ31‐EGCG/HA were significantly lower than those of AZ31. On the basis of inhibiting the excessive corrosion of the substrate, the composite coating significantly improves the compatibility of pre‐osteoblasts, supports the adhesion and spreading and effectively reduces the haemolysis rate to less than 5%. The preparation method of the coating is simple, low cost and suitable for complex shape surfaces, which can significantly improve the corrosion resistance and biocompatibility of the AZ31 substrate. It is expected to provide a solution for the surface modification of magnesium‐based bone implants. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) is widely used as an excellent UV absorbent to improve UV‐shielding ability. However, its photocatalytic activity is high, and the UV absorption region and dispersibility within the polymer are poor, which limits the application. This work is based on the design of ZnO nanoparticles via the coating of hydroxyapatite (HA) and (3‐aminopropyl) triethoxysilane (KH550), then it is compounded with polyvinyl chloride (PVC). X‐ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), high‐resolution transmission electron microscopy (HRTE), and UV spectrophotometer are used to analyze the microstructure and properties. The results show that the composite films have good UV‐shielding abilities and help reduce the damage of PVC upon exposure or heat. Therefore, this work provides new means to make PVC composites with superior UV‐shielding properties, and the tensile strength at the break of PVC film blended with ZnO@HA/KH550 is effectively improved, which is due to good compatibility between ZnO@HA/KH550 and PVC matrix. [ABSTRACT FROM AUTHOR]

Titanium (Ti) exhibits superior biocompatibility and mechanical properties but is bioinert, while hydroxyapatite (HA) possesses excellent osteogenesis and is widely used for the modification of Ti surface coatings. However, the synthesis of homogeneous and stable HA on metallic materials is still a major challenge. In this study, porous titanium dioxide nanotube arrays were prepared on Ti surface by anodic oxidation, loaded with calcium and phosphorus precursors by negative pressure immersion, and HA coating was formed by in situ crystallization of calcium and phosphorus on the surface by hydrothermal heating. Scanning electron microscopy (SEM), X‐ray diffraction (XRD), and bonding strength were conducted to confirm the surface characteristics of each group. The cell proliferation, mineralization degree, and alkaline phosphatase (ALP) activity of MC3T3‐E1 cells on samples were calculated and compared in vitro experiments. Cylindrical samples were implanted into rat femurs to evaluate biocompatibility and osteogenesis in vivo. The results showed that HA crystals successfully synthesized in TiO2 nanotubes, enhancing the bonding strength of HA coating and Ti substrate under negative pressure. Moreover, HA coating on Ti substrate remarkably enhanced cell proliferation and osteogenic differentiation activity in vitro, and improved new bone formation as well as osseointegration in vivo. [ABSTRACT FROM AUTHOR]

Magnetically‐actuated soft robots for medical applications are required to be functional, biocompatible, as well as capable of robust motion inside human organs. In this paper, a ring‐shaped magnetic soft robot, with a flexible biopolymeric film coating, capable of motion on mucus‐coated surfaces is designed and investigated. The biopolymeric film made from chitosan–glycerol (C–G) solution endows the robot with robust locomotion capabilities on surfaces of diverse geometrical shapes and orientations. By utilizing mucoadhesive locomotion, the robot has the potential to carry out clinical procedures on enclosed mucus‐coated tissue surfaces. Material characterization shows that the mucoadhesion increases with the increase of contact times and/or preload forces. The softness of the C–G film can be adjusted by controlling the concentration of glycerol. The ring‐shaped design and magnetization profile decouple the locomotion and functions of the robot. Additionally, the C–G film‐coated robot is tested to be biocompatible for a human colorectal adenocarcinoma cell line with epithelial morphology (HT29). The C–G film reduces the negative effects (superoxide generation) of ferromagnetic particles. Three robot functions including pick‐and‐place, cargo transportation, and liquid capsule release are demonstrated on different surfaces to show the maneuverability, functionality, and potential of implementing clinical procedures through mucoadhesion. [ABSTRACT FROM AUTHOR]

In this review paper, different methods of hydroxyapatite‐based coatings on external fixation pins with improvement in the adhesion strength are explained. Different coating methods such as dip coating, surface‐induced mineralization, plasma spraying, physical vapor deposition magnetron sputtering, micro‐arc oxidation, electrophoretic deposition, chemical vapor deposition, ion beam assisted deposition, sol‐gel dip coating, pulsed laser deposition, and electrohydrodynamic coating are investigated. The micro‐arc oxidation method showed high degradation delaying of the substrate with a high‐voltage electrolyte solution. Moreover, controlling the coating porosity by applying the gas is a good feature of the physical vapor deposition magnetron sputtering method. The comparison of the hydroxyapatite (HA) coatings method showed that the plasma spraying method leads to better coating features between the coating methods on the implant pins. [ABSTRACT FROM AUTHOR]

Background: The use of spinal instrumentation is an established risk factor for postoperative infection. To address this problem, we prepared silver‐containing hydroxyapatite coating, consisting of highly osteoconductive hydroxyapatite interfused with silver. The technology has been adopted for total hip arthroplasty. Silver‐containing hydroxyapatite coating has been reported to have good biocompatibility and low toxicity. However, no studies about applying this coating in spinal surgery have addressed the osteoconductivity and direct neurotoxicity to the spinal cord of silver‐containing hydroxyapatite cages in spinal interbody fusion. Aim: In this study, we evaluated the osteoconductivity and neurotoxicity of silver‐containing hydroxyapatite‐coated implants in rats. Materials & Methods: Titanium (non‐coated, hydroxyapatite‐coated, and silver‐containing hydroxyapatite‐coated) interbody cages were inserted into the spine for anterior lumbar fusion. At 8 weeks postoperatively, micro‐computed tomography and histology were performed to evaluate the osteoconductivity of the cage. Inclined plane test and toe pinch test were performed postoperatively to assess neurotoxicity. Results: Micro‐computed tomography data indicated no significant difference in bone volume/total volume among the three groups. Histologically, the hydroxyapatite‐coated and silver‐containing hydroxyapatite‐coated groups showed significantly higher bone contact rate than that of the titanium group. In contrast, there was no significant difference in bone formation rate among the three groups. Data of inclined plane and toe pinch test showed no significant loss of motor and sensory function in the three groups. Furthermore, there was no degeneration, necrosis, or accumulation of silver in the spinal cord on histology. Conclusions: This study suggests that silver‐hydroxyapatite‐coated interbody cages produce good osteoconductivity and are not associated with direct neurotoxicity. [ABSTRACT FROM AUTHOR]

Currently, there is a growing market for implant coatings that efficiently ward off bacterial infections while aiding in clinical osseointegration. Due to its potential to have a number of functions (including osteogenic activity and antibacterial activity) for bone implantation, the hydroxyapatite (HA) coating doped with multiple ions has drawn a lot of attention. In this study, innovative nanohydroxyapatite coatings containing simultaneous Sr2+, Mn2+, and Ag+ substitutions (MnSrAgHA) were devised and effectively electrodedeposited on pure titanium. That is, the antibacterial ability of MnSrAgHA was enhanced by Ag+, Sr2+ and Mn2+ not only can balance the potential cytotoxicity of Ag+, but also can improve the bone repair rate of composite materials. Some experimental (FE‐SEM, XPS and EDS, etc.) results about the characterization show that Sr2+, Mn2+ and Ag+ can uniformly combine into the HA lattice to form the SrMnAgHA coating. The MnSrAgHA coating surface was rather dense, with numerous needle‐like or flower cluster crystals, and the coating thickness is approximately 10 μm. Moreover, compared with other coatings (HA, AgHA and SrAgHA), the MnSrAgHA coating had a smaller roughness and higher contact angle. However, the contact angle of MnSrAgHA was still within the hydrophilic range. Staphylococcus aureus growth was inhibited by the MnSrAgHA coating, and the antibacterial rate was almost 100 %. The MnSrAgHA coating dramatically enhanced cell proliferation, adhesion, and differentiation abilities, according to in‐vitro cell culture studies. As expected, osteoblasts are not significantly cytotoxic by the MnSrAgHA coating. Due to its adaptability, the multi‐element co‐doped HA coating (MnSrAgHA) offers enormous clinical application potential in anti‐infective repair. [ABSTRACT FROM AUTHOR]

Objectives: 3D‐printing scaffold with specifically customized and biomimetic structures gained significant recent attention in tissue engineering for the regeneration of damaged bone tissues. However, constructed scaffolds that simultaneously promote bone regeneration and in situ inhibit bacterial proliferation remains a great challenge. This study aimed to design a bone repair scaffold with in situ antibacterial functions. Materials and Methods: Herein, a general strategy is developed by using epigallocatechin‐3‐gallate (EGCG), a major green tea polyphenol, firmly anchored in the nano‐hydroxyapatite (HA) and coating the 3D printed polymerization of caprolactone and lactide (PCLA) scaffold. Then, we evaluated the stability, mechanical properties, water absorption, biocompatibility, and in vitro antibacterial and osteocyte inductive ability of the scaffolds. Results: The coated scaffold exhibit excellent activity in simultaneously stimulating osteogenic differentiation and in situ resisting methicillin‐resistant Staphylococcus aureus colonization in a bone repair environment without antibiotics. Meanwhile, the prepared 3D scaffold has certain mechanical properties (39.3 ± 3.2 MPa), and the applied coating provides the scaffold with remarkable cell adhesion and osteogenic conductivity. Conclusion: This study demonstrates that EGCG self‐assembled HA coating on PCLA surface could effectively enhance the scaffold's water absorption, osteogenic induction, and antibacterial properties in situ. It provides a new strategy to construct superior performance 3D printed scaffold to promote bone tissue regeneration and combat postoperative infection in situ. [ABSTRACT FROM AUTHOR]

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

Summary: In this study, the effect of alginate‐based coatings charged with quercetin glycoside compounds and hydroxyapatite/quercetin glycoside compounds (HA/QUE) on the microbiological quality, and on bioactive compounds of fresh‐cut papaya, was evaluated for 14 days at 6 °C. Alginate coatings with hydroxyapatite/quercetin showed a high capability to slow down the growth of all microbiological parameters investigated. At the end of cold storage, the total bacteria count in papaya samples covered with HA/QUE alginate coating was 4.8 log CFU g−1 which is significantly lower (P < 0.05) than 8.3 log CFU g−1 for uncoated samples. Total carotenoids' percentage decrease, at the end of storage, was about 20% in papaya with active coatings, with respect to the losses of 39 and 35%, registered in uncoated and alginate‐coated samples respectively. Vitamin C content and the antioxidant activity measured in papaya coated with HA/QUE alginate showed significantly higher values (P < 0.05) for each storage day than those detected for control‐ and alginate‐coated samples. Based on the sensory evaluation, active‐coated fresh‐cut papaya reached, at the end of the storage period, suitable values for commercial purposes. [ABSTRACT FROM AUTHOR]

Stereolithography and DLP printing attract a lot of attention in medical field as techniques for fabrication of personalized implants and various medical devices. However, there is a lack of photo‐curable resins for fabrication of biodegradable tissue engineering constructs and implants. In this work biodegradable UV‐curable d,l‐lactide oligomers are presented, which can be good candidates as resins for SLA and DLP 3D printing. Linear and star‐shaped (3‐ and 6‐arm) methacrylated d,l‐lactide oligomers with different molecular weight are synthesized and cross‐linked in various conditions. UV‐curing is performed at elevated temperatures in the absence of any diluents and revealed formation of gel fraction, which has achieved 99%. The cross‐linked materials demonstrate high tensile modulus (up to 1.8 GPa), suggesting the resins are perspective for fabrication of load‐bearing implants. [ABSTRACT FROM AUTHOR]

In this study, the dromedary bone waste was valorized by the obtainment of hydroxyapatite (HAp) and its application to remove crystal violet (CV) dye from aqueous solution. Fourier transform infrared spectroscopy, X‐ray diffraction, elemental analysis X‐ray fluorescence spectrometer (XRF), particle size laser analysis, and the point of zero charge pH value (pHpzc) were realized to characterize the natural adsorbent. The capacity of HAp to adsorb CV was measured at different contact times, pH values, and initial dye concentrations. The results showed that the model that better described the experimental data of adsorption kinetics was the pseudo‐second‐order kinetic model (PSO). Freundlich model well fitted the sorption isotherms. A maximum sorption capacity of 266.66 mg/g of CV dye on natural HAp was obtained. Hence, dromedary bone treated might be valorized as a natural adsorbent for water treatment with low environmental risks. [ABSTRACT FROM AUTHOR]

TA6V (Ti‐6Al‐4V) titanium alloy is commonly used in implantology due to its biocompatibility and interesting mechanical properties. However, its lack of bioactivity is responsible for orthopedic implants loosening, eventually leading to the necessity for a revision surgery. In this study, inorganic coatings are developed with the aim of improving osteo‐integration of TA6V implants. To this end, a carbonated calcium phosphate apatite, already reported to be osteo‐conductive and naturally present in bone tissue, is shaped in the form of micro‐sized filaments, via the electrospinning process, in order to mimic the architecture of the collagen fibrils naturally present in the bone extracellular matrix. The process is then adapted to coat complex, 3D implants. Cellular assays with MG‐63 highlight that cell viability and proliferation are promoted on the coated implant, as a result of both its chemical and morphological properties. [ABSTRACT FROM AUTHOR]

The aim of the current study was to recover and separate cobalt ions from multielement solution, using hydroxyapatite (HAp) and magnetic nanocomposite of HAp/Fe3O4 as adsorbents. Cobalt ion adsorption process was conducted batchwise within the temperature 25˗55°C, exposure duration 5˗120 min by applying a dose of 0.25–5 g/L as the adsorbent at pH 2 to 9. Adsorbent characterization was performed using advanced spectroscopic techniques such as Fourier Transform Infrared Spectroscopy, Scanning electron microscopy, and Energy‐dispersive X‐ray spectroscopy. The maximum ionic adsorption efficiency using HAp was 90.48% against 94.72% in the case of the magnetic nanocomposite of HAp, under optimal conditions. Various isotherm models were used to evaluate the adsorption capacity and equilibrium coefficients for adsorption of the cobalt ions by the prepared adsorbents. The isotherm models data showed that the adsorption process is desirable by the adsorbents and by adding nanoparticles of Fe3O4 the adsorption capacity improves. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis and characterization of composites of bioplastics (Poly‐lactic Acid (PLA), Polyhydroxyalkaonate (PHA), and PLA‐PHA blends) filled with dried grains with solubles (DDGS) and hydroxyapatite (HAP) by using a solvent casting process. Detailed microstructural, thermal, and mechanical characterization is presented in the text. At low concentrations of HAP (5–10 vol%) and DDGS (5–31 vol%) additions, the bioplastic films had mechanical integrity, but the ultimate tensile strength (UTS) decreased after the addition of DDGS and HAP reinforcements due to poor adhesion between the bioplastics and fillers. In the intermediate concentration, pre‐pregnated chips of DDGS (31–51 vol%)‐bioplastics and HAP (30–50 vol%)‐bioplastics with dichloromethane (DCM) were partially dried and then hot‐pressed to produce bulk samples (HPC‐process). The addition of bioplastics improved the plasticity of DDGS‐bioplastics composites. The HAP‐bioplastics composites showed polymer dependent response, for example the ultimate compressive strength (UCS) of 50%HAP‐PLA, and 30%HAP‐PLA were 77.6 ± 10.2 and 97.7 ± 5.9 MPa, respectively which are comparable to bone. The DDGS additions increased the hydrophilicity of PLA, PHA, and PLA‐PHA blend. For comparison, HAP increased the hydrophilicity of PHA and PLA‐PHA blends. At higher concentration (bioplastics with 70 vol% HAP additions), the films converted into microencapsulated HAP particles with bioplastics by a simple milling process thus eliminating the need for emulsions and/or surfactants during the microencapsulation process. [ABSTRACT FROM AUTHOR]

In this article, the interplay between structural, electrical, and surface properties in determining the collective behavior of Ca10(PO4)6(OH)2 (hydroxyapatite, HAP) and SrTiO3 (strontium titanate, ST) composites was reported. The monoliths HAP and ST were synthesized using sol‐gel and solid‐state reaction, respectively, and were mixed in different atomic concentrations (20, 40, 60, and 80 at.%) to prepare a series of composites. The prepared composites were then subjected to x‐ray diffraction (XRD) and Raman analysis for probing the microstructural aspects. The analysis revealed no evidence of a phase that the reaction between the two monoliths might form. The crystallite sizes were in the range of 27.2–37.3 nm, and it increased with the content of ST in the composites. The Raman analysis revealed the presence of rutile TiO2 that was later found to be the link in the display of bone‐like apatite nucleation ability in the monolith ST and its composites. The FESEM analysis revealed that the grain sizes were 64–144 nm between the monoliths and were found to follow a similar trend to the crystallite size. The dielectric constant (ϵr) varied with temperature ranging from 5 to 35 (1 MHz) at 310 K for all the specimens. The dependence of ϵr on the grain size of the composites followed a nearly exponential relation. The bone‐like apatite forming ability of the composites was studied by incubating the specimens in simulated body fluid (SBF). Additionally, the cytocompatibility (MG63 cell lines) and protein adsorption (bovine serum albumin [BSA]) of the selected specimens were also studied to comprehensively understand the delicate relationship between the electrical and biological properties. The protein adsorption was primarily related to the surface charge, and its dependence was found to be linear. Additionally, the ϵr of the composites was ≤35, which compliments the protein adsorption behavior of the specimens. The amount of adsorbed protein for all the specimens considered in this study was in the range of 3–32 μ g/ml. Furthermore, the specimens exhibited excellent cell viability of more than 90%. Based on the physical and biological investigations, 20H‐80S was established as the best specimen that blends the characteristic feature of both the monoliths. Finally, the TEM and STEM mapping of the best specimen, projecting the suitability of 20H‐80S in the design of electrically active scaffolds and possibly bioelectrets for biomedical applications, was also studied. [ABSTRACT FROM AUTHOR]

30% carbon fiber reinforced polyetheretherketone (CFR‐PEEK) has in recent times, become significant in the orthopedic industry because its elastic modulus can be engineered to match that of the human bone. But it is bioinert and does not integrate well with the immediate bone tissue environment. In this study, a combined surface modification technique involving ambient temperature sulfonation and surface coating of (hydroxyapatite (HA), 5%reduced graphene oxide hydroxyapatite(5%RGO/HA) and 10%reduced graphene oxide hydroxyapatite(10%RGO/HA) composites) on 30%CFR‐PEEK was achieved with an appropriate temperature treatment at 345°C in nitrogen. The coatings adhered unto the surface of S30%CFR‐PEEK with an improved hydrophilicity and bioactivity. With the sample S30%CFR‐PEEK+HA, having the highest enhanced hydrophilicity from 112.5 ± 2.5° to 20 ± 2° and bioactivity. An improvement in hydrophilicity and bioactivity depicts a change in surface chemistry which will have a positive impact in the interaction of the materials surface with immediate bone environment for a successful application in the orthopedic industry. [ABSTRACT FROM AUTHOR]

Inhibition of oral biofilm formation is critical to prevent and treat dental caries and periodontal diseases. In this study, we synthesized zwitterionic poly(carboxybetaine) (pCB) based polymer as a nonfouling coating to provide anti‐bacterial properties to tooth surfaces. Four catechol derived l‐3,4‐dihydroxyphenylalanine (DOPA) groups were conjugated to pCB to serve as a surface anchoring group. The pCB‐(DOPA)4 polymer was coated on the hydroxyapatite (HA) and enamel samples by simple immersion and characterized by Raman spectroscopy. The nonfouling effectiveness of the pCB based coating was determined by protein adsorption and bacterial adhesion assays. The coating was transparent on sample surfaces. The protein adsorption was significantly reduced to 8.2% and 6.9%, respectively, on pCB‐(DOPA)4 coated HA and enamel samples. The pCB‐(DOPA)4‐coated samples also demonstrated significantly fewer adhered Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus mutants compared to the control. This novel coating material provides an innovative approach to resist biofilm formation on tooth surfaces and has great potential in future dental clinical applications. [ABSTRACT FROM AUTHOR]

Bioactive glasses (BGs) have been used for bone formation and bone repair processes in recent years. This study investigated the titanium substitution effect on 58S BGs (Ti‐BGs) 60SiO2‐(36 − X)CaO‐4P2O5‐XTiO2 (X = 0, 3, and 5 mol.%) prepared by the sol‐gel technique, and the main goal was to find the optimum amount of titanium in Ti‐BGs. Synthesized BGs, which were investigated after immersion in simulated body fluid (SBF), were tested by X‐ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy. Moreover alkaline phosphate (ALP) activity, 3‐(4,5dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay, and antibacterial studies were employed to investigate the biological properties of Ti‐BGs. According to the FTIR and XRD test results, hydroxyapatite (HA) formation on Ti‐BGs surfaces was confirmed. Meanwhile, the presence of 5 mol.% compared to 3 mol.% increased the HA grain distribution and their size on the Ti‐BGs surface. Additionally, MTT and ALP results confirmed that the optimal amount of titanium substitution in BG was 5 mol.%. Since 5 mol.% Ti incorporated BG (BG‐5) had the highest biocompatibility level, antibacterial properties, maximum cell proliferation, and ALP activity among the synthesized Ti‐BGs, it is presented as the best candidate for further in vivo investigations. [ABSTRACT FROM AUTHOR]

Periosteal expansion osteogenesis (PEO) results in the formation of new bone in the gap between periosteum and original bone. The purpose of this study is to evaluate the use of a polyethylene terephthalate (PET) membrane as an activation device. A dome‐shaped PET membrane coated with hydroxyapatite/gelatin on the inner side was inserted between the elevated periosteum and bone at the rabbit calvaria. In the experimental group, the membrane was pushed, bent, and attached to the bone surface and fixed with a titanium screw. In control group, the membrane was only inserted and fixed with titanium screw at original shape under the periosteum. After 7 days, the screw was removed and the mesh was activated in the experimental group. Three animals per group with or without setting a latency period for activation were sacrificed at 3 and 5 weeks after surgery. Bone formation was evaluated via micro‐computed tomography and determined by histomorphometric methods and histological evaluation. No PET membrane‐associated complications were observed during this study. The quantitative data by the area and the occupation of newly formed bone indicated that the experimental group had a higher volume of new bone than the control group at 3 weeks after surgery. Histologically, bone formation progressed to areas adjacent to the cortical perforations; many sinusoidal vessels ran from the perforations to overlying fibrous tissue via the new bone. No bone or obvious inflammatory cells were observed over the membrane. The PET membrane has biocompatible device for PEO that induces a natural osteogenic response at the gap between the original bone and periosteum. [ABSTRACT FROM AUTHOR]

Smart designs of hydroxyapatite (HAp) materials with customized electrical properties are drawing increasing attention for their wide range of potential applications. Such enhanced electrical properties directly arise from the number and orientation of OH− groups in the HAp lattice. Although different polarization treatments have been proposed to enhance the final conductivity by generating vacancies at high temperatures and imposing specific OH− orientations through electric voltages, no direct measurement showing the evolution that OH− groups undergo has been described yet. In this article, the first direct empirical observation that allows the characterization of both the generation of vacancies and the polarization of OH− groups is reported. The mechanisms behind the electrical enhancement are elucidated allowing to distinguish between charge accumulation at the crystal grains, which is due to the formed vacancies, and charge accumulation in the boundaries of particles. In addition, a linear dependence between the number of vacancies and the superficial charge is observed. Therefore, it is demonstrated that the charge accumulation at the micrometric grain boundaries has a great impact on the catalytic properties of the thermally stimulated polarized HAp. These results will be used for further optimization of the catalyst properties. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAP) is one of the most attractive calcium phosphates which is used for different applications. While HAP has been mostly synthesized using wet methods, recently solid‐state synthesis methods have attracted more attention. Many efforts have been made to better understand the solid‐state synthesis mechanism. In this study, the kinetics of the solid‐state reaction between hydroxide calcium (Ca(OH)2) and phosphorus pentoxide (P2O5) was studied under nonisothermal conditions using isoconversional methods. The phase analysis revealed that HAP is the main product of this process with no impurity. Thermogravimetric (TG) curves were recorded at four heating rates (β = 5, 10, 12 and 15°C⋅min−1) and analyzed by several well‐known isoconversional methods. Activation energy values were determined for each extent of reaction, which varied from ∼139 to 100 kJ/mol at the reaction extent of 0.1–0.9. Comparison between activation energy values obtained by isoconversional methods revealed that Flynn–Ozawa–Wall and Vyazovkin's method are more accurate than other. The preexponential factor and the reaction model were determined through model‐free methods. The obtained results indicated that the reaction mechanism was chemically controlled or ordered‐based model. Furthermore, the results showed that formation of HAP does not depend on the heating rate; however, it proceeds with increasing temperature. [ABSTRACT FROM AUTHOR]

The addition of bio‐inert ceramics such as alumina and zirconia can significantly improve the mechanical properties of hydroxyapatite bioactive coatings and increase their biocompatibility. In the present study, the surface of a titanium substrate was coated by the electrophoretic deposition method (EPD). Moreover, the reaction bonding process has been used to precipitate the nanocomposite containing the hydroxyapatite (HA), alumina, yitteria‐stabilized zirconia (YSZ). The coating process was performed by an electrical power supply and a suspension of hydroxyapatite, aluminum, and YSZ nanopowders. For preparing a suspension consisting of 50% isopropanol and 50% acetone, 0.6 g/L of iodine was used as a stabilizer. Green and sintered coatings were analyzed by FE‐SEM and XRD. In addition, the mechanical properties such as bonding strength, hardness, and toughness were measured. The hardness, bonding strength, and toughness of the HA coating were 107 ± 10.3 HV, 10.8 ± 3.2MPa, and 0.72MPa√m, respectively, while those of the HA‐Al2O3‐YSZ nanocomposite coating were 213 ± 1.8 HV, 35 ± 1.6MPa, and 1.6MPa√m, respectively. [ABSTRACT FROM AUTHOR]

The development of a new kind of material that is a nanostructured catalytic material with an environmentally benign nature that can be used for alternative energy has acquired significance in recent years. In this context, the use of heterogeneous catalysts for the transesterification of vegetable oils has gained prominence due to their eco‐friendly and reusable nature. Hence in the present study, pure hydroxyapatite (HAp) and hydroxyapatite/platinum (HAp/Pt) nanostructured particles have been prepared successfully through a facile chemical method without templates and surfactants and their catalytic activity investigated for transesterification of natural vegetable oil to bioenergy (biodiesel). The textural and structural features of pure HAp and HAp/Pt were investigated using various characterization techniques such as x‐ray diffraction, Fourier transform infrared (FTIR) and Raman spectroscopy, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The elements present in the prepared nanostructures were confirmed through energy dispersive spectroscopy (EDS) and x‐ray photoelectron spectroscopy (XPS) techniques. The XPS analysis also confirms the metallic nature of the platinum in HAp/Pt. The specific surface area and porous nature of the prepared nanostructured catalysts were studied using the N2 physisorption Brunauer‐Emmett‐Teller‐Barrett‐Joyner‐Halenda (BET‐BJH) method. The catalytic activity of the pure HAp nanoparticles and HAp/Pt core shell nanorods with the Simarouba glauca plant seed oil was investigated. The obtained results indicate that the pristine HAp nanoparticles and HAp/Pt core shell nanorods (NRs) show 91.4% and 87.1% fatty acid methyl ester (FAME) conversion, respectively, potentially offering environmental benign biocatalysts for biofuel production from natural feed stock. [ABSTRACT FROM AUTHOR]

Highly biocompatible and efficiently luminescent whiskers of the hydroxyapatite (Ca10(PO4)6(OH)2, HAp) doped with various concentrations (0‐5 at.%) of europium were prepared by hydrothermal synthesis and the Eu‐doped Hap‐coating layers onto the surface of titanium substrate were fabricated by the electrophoretic deposition (EPD) process for fluorescent probe application. The maximum doping concentration of Eu accommodating into the host lattice of HAp was detected as ~1.5 at.% and all the hydrothermally synthesized Eu‐doped HAp whiskers were found to have high crystallinity and orientation growth along the c‐axis by X‐ray diffraction (XRD) identification. The valence of the doped Eu was identified as trivalent and divalent coexistence at a concentration percentage of Eu3+: Eu2+ = 78%: 22% by X‐ray photoelectron spectroscopy (XPS) spectra. The replacement site of the doped Eu ions in the crystal structure of HAp host was clarified by Rietveld refinement. The whisker morphology of the hydrothermally synthesized particle was demonstrated by field‐emission scanning electron microscopy (FE‐SEM) observation and their component elements were analyzed by energy dispersive X‐ray (EDX) mapping. The photoluminescence (PL) emissions of the Eu‐doped HAp whiskers and fabricated their coating layers were both revealed mainly at ~615 nm (5D0 → 7F2) and ~697 nm (5D0 → 7F4), which is a wavelength that easily transmitting through living system for biological imaging. The PL emission are falling in the region of reddish orange and belonging to color temperature below 1500 K. Decay time and internal and external quantum efficiencies (QEs) were also measured to reveal them depending on the doping concentration of Eu. The hydrothermally prepared Eu‐doped HAp whiskers would be aimed at biomedical application, due to their promising fluorescent function of probe for in vivo imaging in medical diagnose by utilizing the superior biocompatibility of the HAp host and highly efficient luminescent property of the Eu activator. [ABSTRACT FROM AUTHOR]

Owing to enhanced biocompatibility and osseointegration, hydroxyapatite (HAp) coatings are often applied to biomedical devices that are implanted directly on the bone. Although various HAp coating techniques have been developed, they are restricted due to the time‐consuming HAp synthesis and additional coating processes. Herein, the development of a rapid single‐step method for simultaneous synthesis and coating of HAp via nanosecond laser surface treatment is described. In the conventional HAp‐coating method, the resulting interface between the HAp layer and the base material is clearly distinguished. However, in this method, HAp synthesis and coating occur simultaneously via the melting of the base material (i.e., titanium, polyetheretherketone, and polycaprolactone) to form a gradient HAp‐base material composite coating layer. The resultant coating layer on a titanium surface exhibits a binding force of 31.7–47.2 N, which is sufficient for medical implant applications. Changing the laser irradiation conditions provides quantitative adjustment of the HAp formation process and coating layer thickness. Furthermore, the resulting HAp coating layer better facilitates the attachment of bone cells. These results offer a breakthrough in the surface treatment of bone‐bonding sites of metal and polymer biomedical devices. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) as a potential material for biodegradable implants is attractive due to its mechanical similarity to the bone tissue and nontoxic corrosion products. However, the rapid corrosion rate of bare magnesium is associated with hydrogen release, which may complicate the healing process. The corrosion rate may be reduced by suitable alloying, but concurrently the biocompatibility of such alloy might be deteriorated. Another way of reduction of the corrosion rate is coating. Hydroxyapatite (HA)‐based coating is considered to improve biocompatibility as well as decrease the corrosion rate by the barrier effect. In this study, ultrathin (150 nm) HA and HA containing Sr coatings are deposited via pulsed electron ablation technique on pure Mg. The microstructure of the coating was assessed by scanning electron microscopy. Electrochemical methods were used to investigate the corrosion properties of prepared coatings. The materials covered by this layer were characterized by superior corrosion behavior, with corrosion rates of coated samples up to five times lower as compared with the uncoated ones. Such coating is the thinnest coating found in the literature sources. [ABSTRACT FROM AUTHOR]

Development of bioceramic coatings on the metallic implant surface with superior properties such as good bonding strength, better corrosion resistance and bioactivity was one of the key tasks for the present biomaterial scientists. Hydroxyapatite (Ca10 (PO4)6(OH)2) was one of the hopeful calcium phosphate‐based ceramic biomaterials which can be enforced as a layer on the metallic substrate due to its resemblance with the human bone in chemical composition. Current effort defines the in‐situ blending of HAP/graphene oxide composite by the sol‐gel process. The prepared HAP/GO composites were characterized using FT‐IR, XRD, SEM and TEM analysis. A triple‐layered composite coating was attained at the spin speed of 3000 rpm/min further sintered at 600 °C for 2 hrs. In‐vitro corrosion resistance behavior of the coatings on 316 L SS implant were studied on simulated body fluid. The average crystallite size of the synthesized powders was reduced from 40.58 to 21.08 nm with the addition of graphene oxide, anti‐bacterial study for the HAP/GO composite powder competently inhibits the growth of pathogens. Electrochemical studies and adhesion studies showed increased corrosion resistance with superior bonding strength on 316 L SS surface, which results its use for long term biomedical applications. [ABSTRACT FROM AUTHOR]

The prospect of modifying the surface properties of the substrate (or base) material to enhance its corrosion and wear resistance as well as its reliability, performance, and more importantly its bioactivity is made possible using nanocoatings. An effective technique of synthesizing high purity nanocoatings in addition to nanopowders and fibers is to utilize the sol‐gel approach. It is an attractive and versatile method that can be carried out with relative ease. Ceramic coatings, such as hydroxyapatite (HAp), can be fabricated through chemical means from solutions and consequently complex shapes can be coated economically. Given the fact that mixing takes place on the atomic scale, one of the key advantages of the sol‐gel technique is its capacity to produce homogeneous materials, and it has been shown that the mechanical properties of sol‐gel coatings are enhanced due to the presence of nanocrystalline grain structures. This review covers a brief insight into the recent application of HAp nanocoatings derived from sol‐gel technique. [ABSTRACT FROM AUTHOR]

Summary: This paper presents new results of studying the influence of parameters of microplasma spraying (MPS) of Ti wire on the structure and properties of Ti coatings. Based on the design of the experiment and the results of the SEM study, certain spraying modes were chosen to form the desired composition and structure of the Ti coating. The dense sublayer (up to 300 µm thick) provides good adhesion to the substrate, and a porous top layer can accelerate the coated implant ingrowth with the bone. This technology is developed for the manufacture of coated endoprosthesis implants. [ABSTRACT FROM AUTHOR]

In this study, an original method of macromolecular design was used to develop a hyaluronidase‐1 (HYAL1) inhibitor from its principal substrate, hyaluronic acid (HA). HA‐based nanoparticles (HA‐NP) were obtained by copolymer self‐assembly and their effects on HYAL1 activity were investigated by combining different analytical tools. Compared to HA, HA‐NP exhibited an enhanced stability against HYAL1 degradation while maintaining its interaction with the HA receptors CD44 and aggrecan. HA‐NP displayed a strong and selective inhibition of HYAL1 activity and retarded the hydrolysis of higher‐molar‐mass HA in solution. A co‐nanoprecipitation process was used to formulate a range of hybrid nanoparticle samples, which demonstrated the specificity and efficiency of HA‐NP in HYAL1 inhibition. [ABSTRACT FROM AUTHOR]

In this present study, in vitro characterization on bioactivity and biocompatibility of the copper‐doped hydroxyapatite (Cu‐HA) coatings deposited onto Ti6Al4V alloy with increasing copper content obtained using solution precursor plasma spray process were evaluated under simulated body fluid (SBF) and cytotoxicity tests. The growth of flake‐like structures was observed at the coatings' surface after 7 days of immersion in SBF. Elemental composition analysis showed a calcium‐deficient carbonate‐containing apatite for the grown layer. Broadening of the HA peaks were also observed in the X‐ray diffraction patterns and infrared absorption spectra of the immersed coatings associated with the possible formation of an amorphous layer at the surface of the coatings. Copper incorporation does not alter the bioactivity of HA but only slowed down for 10 mol% copper content. Cytotoxicity evaluation using MTT assays showed that 3 mol% Cu‐HA coating was not toxic under in vitro characterizations. [ABSTRACT FROM AUTHOR]

Streptococcus mutans is the main pathogen of dental caries and adheres to the tooth surface via soluble and insoluble glucans produced by the bacterial glucosyltransferase enzyme. Thus, the S. mutans glucosyltransferase is an important virulence factor for this cariogenic bacterium. Sulfated vizantin effectively inhibits biofilm formation by S. mutans without affecting its growth. In this study, less S. mutans biofilm formation occurred on hydroxyapatite discs coated with sulfated vizantin than on noncoated discs. Sulfated vizantin showed no cytotoxicity against the human gingival cell line Ca9‐22. Sulfated vizantin dose‐dependently inhibited the extracellular release of cell‐free glucosyltransferase from S. mutans and enhanced the accumulation of cell‐associated glucosyltransferase, compared with that observed with untreated bacteria. Sulfated vizantin disrupted the localization balance between cell‐associated glucosyltransferase and cell‐free glucosyltransferase, resulting in inhibited biofilm maturation. These results indicate that sulfated vizantin can potentially serve as a novel agent for preventing dental caries. [ABSTRACT FROM AUTHOR]

Spray drying (SD) has the ability to tailor granule size and morphology, thus, it is used for producing hydroxyapatite (HA) granules. Recently, Sr functionalized HA (SrHA) has been recommended owing to its improved biological properties. The aim of this article was to produce SrHA granules with the combination of nanoparticle synthesis and spray‐drying. The effects of substitution on the physical properties of SrHA nanoparticles and spray‐dried granules were investigated. TEM analyzes revealed that Sr substitution reduced the mean size of HA nanoparticles from 4.59 nm to 2.31 nm. Besides, Sr substitution increased the viscosity of the prepared slurry for spray drying, which may be attributed to the smaller nanoparticle sizes. The reduced nanoparticle size caused to the agglomeration of the SrHA more than the pure HA nanoparticles. Moreover the 16 mol % Sr substituted HA (16SrHA) slurry were quickly hardened, which hampered the feeding of the slurry to the SD system; eventually the atomizer was blocked. The increase in the viscosity increased the mean granule size of HA from 41.53 µm to 49.18 µm. HA and 8SrHA granules presented HA phase dominantly after the heat treatment at 1000°C, while, 16SrHA decomposed to TCP according to RAMAN and XRD investigations. [ABSTRACT FROM AUTHOR]

We investigated a fabrication technique of c‐plane‐oriented hydroxyapatite (HA) crystalline film on low‐cost amorphous SiO2 substrates to apply the orientation‐controlled HA crystal to disposal biochips. An experiment was conducted by the pulsed laser deposition method. We showed that a high‐quality HA crystalline film was grown using a fluorapatite (FA) buffer layer, which was self‐oriented on amorphous SiO2. A relationship between an FA‐film thickness and the HA quality was examined with an aim of minimizing a toxic risk of F to biomolecules, even if it was eluted from FA. It was found that the thickness of the FA film could be reduced to about 7.5 nm, at the same time, the crystallinity and smoothness of HA were also excellent. A crystal growth model of FA on the amorphous SiO2 was also studied. We considered that highly reactive F in a laser‐ablated plume substituted for O on the substrate surface, which became a migration trap, causing three‐dimensional island growth as FA crystal nuclei. This model consistently agreed with a series of experimental results. [ABSTRACT FROM AUTHOR]

Eco‐friendly catalysts have been obtained by functionalizing hydroxyapatite (HAP) with iron (Fe/HAP), according to three preparative methods (flash ionic exchange, deposition‐precipitation, and impregnation). Fe/HAP samples (ca. 2–7 wt.% Fe) have been tested in the reaction of NOx reduction by ammonia (NH3‐SCR) in the 120–500 °C interval with different NH3/NO ratios (0.6–2) at fixed contact time (0.12 s). All Fe/HAP samples were active and selective in the NH3‐SCR reaction starting from ca. 350 °C. Better performances have been observed on catalysts prepared by deposition‐precipitation and impregnation (about 70 % of NOx conversion and selectivity to N2 higher than 95 % at 350 °C), where α‐Fe2O3 and 3D‐Fe2O3 nanoclusters were present, as indicated by Mössbauer and UV‐Vis‐DR spectroscopies. On the opposite, paramagnetic Fe3+ centres were the predominant species on samples prepared by flash ionic exchange. Further characterization techniques (XRPD, N2‐physisorption, acidity by NH3 adsorption, and H2‐TPR) have concurred to elucidate Fe‐sitting HAP and structure‐activity relationships. [ABSTRACT FROM AUTHOR]

Erysipelothrix piscisicarius is an emergent pathogen in fish aquaculture, particularly in the ornamental fish trade. Very little is known on the biology of this pathogen; however, the recurrence of infection and disease outbreaks after removing the fish from a system and disinfecting the tank suggest its environmental persistence. Moreover, biofilm lifestyle in E. piscisicarius has been suspected but not previously shown. The purpose of this study was to investigate the formation of biofilms on an abiotic surface in Erysipelothrix spp. We used hydroxyapatite‐coated plastic pegs to demonstrate the attachment, growth, and persistence of E. piscisicarius on abiotic surfaces in both fresh and marine environments and to investigate the susceptibility of this pathogen to different disinfectants that are used in the aquaculture industry. E. piscisicarius formed biofilms that persisted significantly longer than planktonic cells did in both freshwater and saltwater over a period of 120 h (P = 0.004). The biofilms were also more resistant to disinfectants than the planktonic cells were. Hydrogen peroxide was the most effective disinfectant against E. piscisicarius, and it eradicated the biofilms and planktonic cells at the recommended concentrations. In contrast, Virkon and bleach were able to eradicate only the planktonic cells. This information should be taken into consideration when developing biosecurity protocols in aquaculture systems, aquariums, and private collections. [ABSTRACT FROM AUTHOR]

Aim: To investigate the anti‐biofilm efficacy and working mechanism of several NaOCl concentrations on dual‐species biofilms of different architecture as well as the changes induced on the architecture of the remaining biofilms. Methodology: Streptococcus oralis J22 and Actinomyces naeslundii T14V‐J1 were co‐cultured under different growth conditions on saliva‐coated hydroxyapatite discs. A constant‐depth film fermenter (CDFF) was used to grow steady‐state, four‐day mature biofilms (dense architecture). Biofilms were grown under static conditions for 4 days within a confined space (less dense architecture). Twenty microlitres of buffer, 2‐, 5‐, and 10% NaOCl were applied statically on the biofilms for 60 s. Biofilm disruption and dissolution, as well as bubble formation, were evaluated with optical coherence tomography (OCT). The viscoelastic profile of the biofilms post‐treatment was assessed with low load compression testing (LLCT). The bacteria/extracellular polysaccharide (EPS) content of the biofilms was examined through confocal laser scanning microscopy (CLSM). OCT, LLCT and CLSM data were analysed through one‐way analysis of variance (ANOVA) and Tukey's HSD post‐hoc test. Linear regression analysis was performed to test the correlation between bubble formation and NaOCl concentration. The level of significance was set at a < 0.05. Results: The experimental hypothesis according to which enhanced biofilm disruption, dissolution and bubble formation were anticipated with increasing NaOCl concentration was generally confirmed in both biofilm types. Distinct differences between the two biofilm types were noted with regard to NaOCl anti‐biofilm efficiency as well as the effect that the several NaOCl concentrations had on the viscoelasticity profile and the bacteria/EPS content. Along with the bubble generation patterns observed, these led to the formulation of a concentration and biofilm structure‐dependent theory of biofilm removal. Conclusions: Biofilm architecture seems to be an additional determining factor of the penetration capacity of NaOCl, and consequently of its anti‐biofilm efficiency. [ABSTRACT FROM AUTHOR]

Several antibacterial materials have been developed to prevent periprosthetic joint infection and thus prevent serious complications for patients and surgeons. However, no study has addressed the activity of antibacterial materials against hematogenous infection. The present study evaluated the antibacterial activity of a silver‐containing hydroxyapatite‐coated implant against methicillin‐resistant Staphylococcus aureus (MRSA) hematogenous infection. Implants coated with hydroxyapatite and silver‐hydroxyapatite were inserted into rats' right and left femurs, respectively, after which the animals were infected with S. aureus via a tail vessel. About 107 colony‐forming units was the optimal bacterial number for the establishment of S. aureus hematogenous infection. Bacterial loads and C‐reactive protein in the blood were measured to confirm bacteremia and inflammation. Fourteen days after the infection, bacterial loads were statistically lower in the femurs containing silver‐hydroxyapatite‐coated implants than in those with hydroxyapatite‐coated implants (p = 0.022). Thus, silver‐hydroxyapatite‐coated implants might provide antibacterial activity against MRSA hematogenous infection in the postoperative period. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2655–2660, 2019 [ABSTRACT FROM AUTHOR]

A rapid response/recovery ribbon‐like hydroxyapatite (HAp) humidity sensor with loose spatial structure has been fabricated in this work. The HAp film was prepared on polyethylene terephthalate‐indium tin oxide (PET‐ITO) interdigital substrate by electrochemical deposition method. The HAp film was characterized by XRD, SEM, FTIR techniques. Electrochemically deposited HAp has a preferred orientation in a‐plane, which exposes a great many of hydroxyl groups. The HAp has a flat ribbon‐like microstructure that effectively captures and detects water molecules. The gap of the interdigital electrode was filled with long ribbon‐like HAp to form a loose spatial structure which facilitates water molecules adsorption and desorption. The HAp humidity sensor showed high sensitivity, low hysteresis and good linearity. In particular, HAp sensor has a short response time of 0.9 s and recovery time of 5.6 s. Besides, the humidity sensing mechanism of HAp sensor was also investigated in detail. [ABSTRACT FROM AUTHOR]

In this study, the hydroxyapatite (HA)‐titanium (Ti, 20 wt.%) multiwalled carbon nanotubes (MWCNTs, 1 wt.%) composite coating was applied on the NiTi alloy by using the electrophoretic deposition (EPD) technique. The morphologies and the phase structures of the coatings were investigated by the FESEM and XRD analysis, respectively. The corrosion behaviors of the coated NiTi samples were investigated using the polarization and electrochemical impedance spectroscopy tests in a simulated body fluid (SBF). The amounts of the released Ni ions from the coated NiTi were studied in the SBF. The results of the electrochemical tests revealed the corrosion resistance of the NiTi coated with HA was further improved by the addition of the Ti and MWCNTs to the HA coating. The current density and corrosion resistance of the NiTi alloy changed from 2.52 μA.cm−2 and 24.13 kΩ to 0.91 nA.cm−2 and 5.92 MΩ after coated with the HA‐Ti‐MWCNTs composite coating. Also, the number of nickel ions released from the surface of the NiTi alloy to the SBF medium suppressed from 11.8 to 0.08 μgr.L−1, after coating with HA‐Ti‐MWCNTs. Also, the cellular proliferation in the culture medium consisting of the NiTi alloy coated with the HA‐Ti‐MWCNTs improved significantly (compared with that of the NiTi alloy) as shown no toxicity in the cell culture medium. [ABSTRACT FROM AUTHOR]