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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]

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]

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]

This paper reports on electrophoretic deposition of hydroxyapatite coatings on 316L stainless steel and Ti6Al4V alloy. Coatings were carried out at 60 sec. deposition time and voltage values of 40, 80, 120, 160 Voltage. Suspension: It was prepared by using Ethanol, Hydroxyapatite, Polyvinyl Alcohol, Sodium dodecyl sulfate, N-N-Dimethylformamide chemicals. The findings and results acquired at the end of the study have been presented and discussed. When the Ca/P values calculated in the study are examined, it was seen that there are values close to the ideal Ca/P ratio (1.67) in all parameters. When the roughness values are examined, it was seen that coatings close to the ideal surface roughness value (1-1.5 µm) are obtained. When the nano indentation test results were evaluated, it was observed that coatings suitable for shell bone implants were obtained. [ABSTRACT FROM AUTHOR]

Vascular transplantation is an effective and common treatment for cardiovascular disease (CVD). However, the low biocompatibility of implants is a major problem that hinders its clinical application. Surface modification of implants with extracellular matrix (ECM) coatings is an effective approach to improve the biocompatibility of cardiovascular materials. The complete ECM seems to have better biocompatibility, which may give cardiovascular biomaterials a more functional surface. The use of one or several ECM proteins to construct a surface allows customization of coating composition and structure, possibly resulting in some unique functions. ECM is a complex three-dimensional structure composed of a variety of functional biological macromolecules, and changes in the composition will directly affect the function of the coating. Therefore, understanding the chemical composition of the ECM and its interaction with cells is beneficial to provide new approaches for coating surface modification. This article reviews novel ECM coatings, including coatings composed of intact ECM and biomimetic coatings tailored from several ECM proteins, and introduces new advances in coating fabrication. These ECM coatings are effective in improving the biocompatibility of vascular grafts. [ABSTRACT FROM AUTHOR]

This study aimed to retrospectively analyze the follow-up results of cases in which the adjacent joint was preserved using a custom-made uncemented short-stem design (hollow stem) with optional external flanches in tumor endoprosthetic replacement due to bone sarcomas in 13 patients (with an average age of 9.6 years) between 2017 and 2023. Reconstructions were proximal femur ( n = 6), intercalary femur ( n = 4), intercalary tibia ( n = 2), and proximal humerus ( n = 1) tumor prostheses. The hollow body was used distally in 10 of the megaprotheses, proximally in 1, and both proximally and distally in 2 of them. The average distance from the joints was 6 cm in stems with flanches and 11.8 cm in stems without flanches. No aseptic loosening or deep infection was observed during an average follow-up of 34 months. Except for one case with a tibial intercalary prosthesis that needed a revision, all cases were well osteointegrated and all lower extremity cases could bear full weight without pain. In cases where the remaining bone stock after bone resection is insufficient for a standard stem implantation, reconstruction with a patient-specific short hollow-stem design appears to be a good alternative to protect healthy joints with high prosthesis survival and low revision rates in the short-term follow-up.

Bone tissue engineering uses various methods and materials to find suitable scaffolds that regenerate lost bone due to disease or injury. Poly(ε-caprolactone) (PCL) can be used in 3D printing for producing biodegradable scaffolds by fused deposition modeling (FDM). However, the hydrophobic surfaces of PCL and its non-osteogenic nature reduces adhesion and cell bioactivity at the time of implantation. This work aims to enhance bone formation, osteogenic differentiation, and in vitro biocompatibility via PCL scaffolds modification with Hydroxyapatite (HA) and Collagen type I (COL). This study evaluated the osteosupportive capacity, biological behavior, and physicochemical properties of 3D-printed PCL, PCL/HA, PCL/COL, and PCL/HA/COL scaffolds. Biocompatibility and cells proliferation were investigated by seeding human adipose tissue-derived mesenchymal stem cells (hADSCs) onto the scaffolds, which were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and 6-diamidino-2-phenylindole (DAPI) staining. In addition, the bone differentiation potential of the hADSCs was assessed using calcium deposition, alkaline phosphatase (ALP) activity, and bone-related protein and genes. Although all constructed scaffolds support hADSCs proliferation and differentiation, the results showed that scaffold coating with HA and COL can boost these capacities in a synergistic manner. According to the findings, the tricomponent 3D-printed scaffold can be considered as a promising choice for bone tissue regeneration and rebuilding. [ABSTRACT FROM AUTHOR]

Zinc-doped hydroxyapatite (Zn-HAp) was used as photocatalyst for degrading Bisphenol A (BPA) in aqueous solution. Zn-HAp was synthesized by co-precipitation method, and its properties were analyzed by X-ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Nitrogen Adsorption–Desorption Isotherms, and Diffuse Reflectance Spectroscopy (DRS). During analysis, the Zn-HAp material showed an increase in light absorption in the region from 240-400 nm and in photocatalytic activity on the process of BPA degradation under UVA radiation (λ = 350 nm). After 240 min of irradiation, the material degraded 82% of the contaminant, showing that Zn-HAp can be used as an UVA light photocatalyst for the removal of BPA. Therefore, Zn-HAp is a promising photocatalyst in water technology. [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]

We study the process of formation of hydroxyapatite coatings on the surface of commercially pure VT1-0 titanium with preliminarily formed nitride layers by the method of plasma-electrolytic oxidation in an alkaline electrolyte (hydroxyapatite + 1 M potassium hydroxide) under a voltage of 160 V with a deposition time of 1 min. It is established that hydroxyapatite with porous structure is formed more rapidly on the nitride layer with greater number of vacancies in the nonmetallic sublattice of titanium mononitride (TiN0.69) than in the presence of smaller number of vacancies (TiN0.81). It was discovered that, for the hydroxyapatite coating, the Ca/P ratio decreases from 1.62 to 0.96. [ABSTRACT FROM AUTHOR]

Calcium phosphates coatings are capable to biofuntionalize surfaces of the Ti-6Al-4V alloy for biomedical implant applications. Synthesis of these coatings by the electrolytic deposition technique allows to determine its properties as well as physical and chemical characteristics in accordance with the electrodeposition process mode and time. Additionally, the condition of the metallic substrate surface determines the adhesion strength with the coating. The coatings were electrodeposited by pulsed and traditional (continuous) modes during 30 and 60 min of time processing, on three different pretreated surfaces with anodizing, pickling and alkaline bath. The coatings obtained through the pulsed mode resulted free of cracks and porosities. Furthermore, with pulsed mode and 60 min of electrodeposition time on the pickled and anodized surface resulted in coatings with a morphology of semi-hexagonal bar clusters, Ca/P and crystallographic structure closer to hydroxyapatite; also, the best adhesion strength. In conclusion, these are the most ideal conditions to improve the biocompatibility and osteointegration properties of the Ti-6Al-4V alloy. The TiO2 nanotube matrix produced by the anodization formed a strong anchorage with the electrodeposited coating, while the titanate layer obtained during the alkaline bath affected the integrity of the coating. [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]

To explore the effect of copper content in a copper-doped hydroxyapatite coating (CuHAp) on its antibacterial activity and biocompatibility, a layer of CuHAp was deposited on the surface of pure Ti using an electrochemical deposition method. An orthogonal experiment was used to determine the Cu content in the coating by varying the concentration of Cu2+ in the electrolyte. The antibacterial properties and biocompatibility of the CuHAp coatings were also evaluated. The antibacterial effect increased with increasing Cu content in the sample. When the content of Cu in the coating was 1.57%, the deposited CuHAp coating exhibited excellent biocompatibility, and the number of living cells after culturing was significantly higher than that for the HAp coating. When the content of Cu increased to 6.85%, the coating exhibited cytotoxicity. Thus, the CuHAp sample with a Cu content of 1.57% exhibited good antibacterial and biocompatibility, and thus could be a suitable material for use in biomedical applications. [ABSTRACT FROM AUTHOR]

An amperometric sensor was developed by depositing a film coating of hydroxyapatite (HA)/L-lysine (Lys) composite material on a glassy carbon electrode (GCE). It was applied for the detection of Nile blue A (NBA). Hydroxyapatite was obtained from snail shells and its structural properties before and after its combination with Lys were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analyses. The coupling of Lys to HA was attributed to favorable interaction between negatively charged -COO− groups of Lys and divalent ions Ca2+ of HA. Electrochemical investigations pointed out the improvement in sensitivity of the GCE/Lys/HA sensor towards the detection of NBA in solution. The dependence of the peak current and potential on the pH, scan rate, and NBA concentration was also investigated. Under optimal conditions, the GCE/Lys/HA sensor showed a good reproducibility, selectivity, and a NBA low detection limit of 5.07 × 10−8 mol L−1. The developed HA/Lys-modified electrode was successfully applied for the detection of NBA in various water samples. [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]

Porous polycaprolactone (PCL)/hydroxyapatite (HA) composite coatings are deposited via suspension flame spraying for marine ecological remediation. The morphology, phase composition, chemical composition, and surface roughness are characterized by scanning electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, and 3D optical profiler. The PCL/HA coatings exhibit porous structure, and the porosity is controlled through adjusting the content of HA. The microalgae attachment performances of Chlorella on the surface of 316L stainless steel substrate and the PCL/HA coatings are investigated. The PCL/HA coatings effectively increase the attachment ratio of Chlorella; after 7 days of incubation, the adhesion ratio is up to 69.8%. The porous structure of the PCL/HA coatings plays a significant role in promoting the attachment of microalgae, which has a valuable application in marine ecological remediation area. [ABSTRACT FROM AUTHOR]

This work intended to elucidate, in an in vitro approach, the cellular and molecular mechanisms occurring during the bone healing process, upon implantation of a tailored degradable multifunctional Mg-based alloy. This was prepared by a conjoining anodization of the bare alloy (AZ31) followed by the deposition of a polymeric coating functionalized with hydroxyapatite. Human endothelial cells and osteoblastic and osteoclastic differentiating cells were exposed to the extracts from the multifunctional platform (having a low degradation rate), as well as the underlying anodized and original AZ31 alloy (with higher degradation rates). Extracts from the multifunctional coated alloy did not affect cellular behavior, although a small inductive effect was observed in the proliferation and gene expression of endothelial and osteoblastic cells. Extracts from the higher degradable anodized and original alloys induced the expression of some endothelial genes and, also, ALP and TRAP activities, further increasing the expression of some early differentiation osteoblastic and osteoclastic genes. The integration of these results in a translational approach suggests that, following the implantation of a tailored degradable Mg-based material, the absence of initial deleterious effects would favor the early stages of bone repair and, subsequently, the on-going degradation of the coating and the subjacent alloy would increase bone metabolism dynamics favoring a faster bone formation and remodeling process and enhancing bone healing. [ABSTRACT FROM AUTHOR]

Mg and its alloys are considered as biodegradable metallic implant materials, are attracting great attentions. However, the corrosion resistance and biocompatibility required to be improved according to clinical demands in bone implants. In this study, Ca-deficient hydroxyapatite ceramic coating is fabricated on AZ31 magnesium alloy's surface by one-step micro-arc oxidation (MAO) in an alkali electrolyte with different calcium glycerophosphate (CaGP) concentrations. The thickness, roughness, morphology, and composition of the coating are dependent on the concentration of CaGP, determining the protective ability of magnesium alloy. The electrochemical test results demonstrated that corrosion resistance of Mg alloy is improved by applying Ca defected hydroxyapatite containing ceramic coatings. In addition, the coating shows a high bonding strength with the substrate with tensile bond strength higher than 35 MPa. Furthermore, the MAO sample shows a longer wear life compared with the substrate. Hydroxyapatite (HA) containing coating with a good combination of corrosion resistance, bonding strength and wear behavior could be obtained by adjusting the concentration of CaGP in the electrolyte solution. [ABSTRACT FROM AUTHOR]

Conductive polypyrrole (PPy) has excellent biocompatibility and structural stability. It is an ideal electroactive biomaterial that can apply exogenous electrical stimulation to promote osteoblast differentiation. However, PPy is a kind of bio-inert material, which does not have osteoinductive capacity. Therefore, we have introduced a kind of bioactive material, hydroxyapatite (HA), to construct PPy/HA composite to enhance bioactivity and osteoinduction. In addition, micron-topological morphology of scattered grid pattern has been designed and introduced to the PPy/HA coatings, which can further enhance the regulation ability of the coatings to the adhesion, proliferation and differentiation of MC3T3-E1 cells. In vitro simulated body fluids (SBFs) immersion test results have demonstrated that the fabricated micropatterned PPy/HA composite coatings perform bioactivity well and can promote the mineral deposition of HA on the surface. Moreover, it can also benefit the proliferation and osteognetic differentiation of MC3T3-E1 cells, when accompanied by external electrical stimulation (ES). In this study, we have successfully constructed electroactive and bioactive coatings, the method of which can potentially be applied to the surface functional modification of traditional bone repair metals. [ABSTRACT FROM AUTHOR]

Ceramic coatings have a long history in the orthopaedic field, with plasma sprayed coatings of hydroxyapatite as leading standard in the manufacturing process; however, these coatings can contain secondary phases resulting from the decomposition of hydroxyapatite at high temperatures, which limit the lifetime of implants and their osseointegration. This work aims to produce coatings that can maximize bone osseointegration of metallic implants. In order to preserve the raw characteristics of hydroxyapatite powders that are thermally unstable, coatings were deposited by cold spray onto Ti6Al4V alloy substrates. In contrast with other thermal spray technologies, this process presents the advantage of spraying particles through a supersonic gas jet at a low temperature. On top of hydroxyapatite, carbonated nanocrystalline apatite was synthesized and sprayed. This biomimetic apatite is similar to bone minerals due to the presence of carbonates and its poor crystallinity. FTIR and XRD analyses proved that the biomimetic characteristics and the non-stoichiometric of the apatite were preserved in the cold spray coatings. The cold spray process did not affect the chemistry of the raw material. The adhesion of the coatings as well as their thicknesses were evaluated, showing values comparable to conventional process. Cold spraying appears as a promising method to preserve the characteristics of calcium phosphate ceramics and to produce coatings that offer potentially improved osseointegration. [ABSTRACT FROM AUTHOR]

Applying antibacterial coatings to dental implant materials seems reasonable but can have negative influences on desired cell adhesion and healing. In this study, zirconia abutment specimens interacting with gingival tissue were used. The aim was to compare the influence of machined or coated zirconia surfaces on the adhesion and proliferation of human gingival fibroblasts (HGF-1). Surface modifications were performed using atmospheric plasma coating with hydroxyapatite, zinc, and copper. Zirconia specimens were divided into four groups: hydroxyapatite, hydroxyapatite with zinc oxide (ZnO), hydroxyapatite with copper (Cu), and an untreated machined surface. After the characterization of the surface conditions, the morphology of adhered HGF-1 was determined by fluorescence staining and subjected to statistical evaluation. The visual analysis of cell morphology by SEM showed flat, polygonal, and largely adherent fibroblast cells in the untreated group, while round to partially flat cells were recorded in the groups with hydroxyapatite, hydroxyapatite + ZnO, and hydroxyapatite + Cu. The cell membranes in the hydroxyapatite + ZnO and hydroxyapatite + Cu groups appeared porous. The results show that HGF-1 adhere and proliferate well on machined zirconia, while plasma coating with hydroxyapatite or hydroxyapatite mixtures does not lead to increased adhesion or proliferation. [ABSTRACT FROM AUTHOR]

This study aims at preparing novel composite materials for the consolidation of damaged stone in built heritage from tetraethoxysilane(TEOS)based sols with nano-sized hydroxyapatite (HAp) with high crystallinity and high aspect ratio. Synthesis of nanostructures of hydroxyapatite (HAp) was carried out using hydrothermal precipitation methods at different reaction temperatures and periods. Rod-like HAp nanostructures with a diameter around 5–20 nm and length up to 125 nm were obtained. The samples of nano-HAp were characterised using powder X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and μ-Raman spectroscopy. The derived nanostructures were used to modify TEOS-based formulations after tuning their colloidal stability period to the needs of their application as stone consolidants. The chemical structure (μ -Raman), viscosity, macroscopic and microscopic morphologies – Scanning Electron Microscopy (SEM) and EDS – and Shore Hardness of the composite materials were studied. The potential of the composite materials containing nano-HAp-rods as stone consolidants revealed to be superior to the potential of reference materials. [ABSTRACT FROM AUTHOR]

Mining and smelting effluent have resulted in heavy metal-contaminated groundwater. Copper-polluted groundwater poses a severe threat to human health and the ecological environment. Permeable reactive barrier (PRB) has been rapidly developed as the in situ remediation technology to control toxic copper migration. Low cost, seepage stability, and great longevity are considered within PRB reactive media. In this paper, hydroxyapatite derived from bovine bone was proven to be a suitable adsorbent owing to cost-effectiveness, great adsorption capacity, and longevity. Batch experiments were carried out to determine the copper adsorption behavior as a function of copper concentration and contact time. Adsorption isotherm was represented by the Langmuir isotherm model, and the adsorption capacity of 25.7 mg/g was superior to most of the adsorbents. A kinetic study was accurately fitted by the pseudo-second-order kinetic model interpreted as a chemical reaction. In addition, the column study confirmed hydroxyapatite has excellent hydraulic performance with no clogging phenomenon happened. At C/C0 = 0.5, the number of pore volume (PV) reached 450. The batch and column experiments also revealed that the overall adsorption process followed up the monolayer chemisorption. Furthermore, systematic analyses demonstrated that surface adsorption was responsible for the copper removal by hydroxyapatite based on experimental analysis and density functional theory (DFT) calculations. This work provides an alternative strategy as filling material for in situ remediation of copper-contaminated groundwater and enriches relevant theoretical references. [ABSTRACT FROM AUTHOR]

Background: The increasing demand for bone implants with improved osseointegration properties has prompted researchers to develop various coating types for metal implants. Atomic layer deposition (ALD) is a method for producing nanoscale coatings conformally on complex three-dimensional surfaces. We have prepared hydroxyapatite (HA) coating on titanium (Ti) substrate with the ALD method and analyzed the biocompatibility of this coating in terms of cell adhesion and viability. Methods: HA coatings were prepared on Ti substrates by depositing CaCO3 films by ALD and converting them to HA by wet treatment in dilute phosphate solution. MC3T3-E1 preosteoblasts were cultured on ALD-HA, glass slides and bovine bone slices. ALD-HA and glass slides were either coated or non-coated with fibronectin. After 48h culture, cells were imaged with scanning electron microscopy (SEM) and analyzed by vinculin antibody staining for focal adhesion localization. An 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) test was performed to study cell viability. Results: Vinculin staining revealed similar focal adhesion-like structures on ALD-HA as on glass slides and bone, albeit on ALD-HA and bone the structures were thinner compared to glass slides. This might be due to thin and broad focal adhesions on complex three-dimensional surfaces of ALD-HA and bone. The MTT test showed comparable cell viability on ALD-HA, glass slides and bone. Conclusion: ALD-HA coating was shown to be biocompatible in regard to cell adhesion and viability. This leads to new opportunities in developing improved implant coatings for better osseointegration and implant survival. [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]

The use of resorbable magnesium alloys in the design of implants represents a new direction in the healthcare domain. Two main research avenues are currently explored for developing or improving metallic biomaterials: (i) increase of their corrosion resistance by designed compositional and structural modifications, and (ii) functionalization of their surfaces by coating with ceramic or polymeric layers. The main objective of this work was to comparatively assess bio-functional coatings (i.e., highly-crystallized hydroxyapatite and silica-rich glass) deposited by radio-frequency magnetron sputtering (RF-MS) on a biodegradable Mg-0.8Ca alloy (0.8 wt.% of Ca). After probing their morphology (by scanning electron microscopy) and structure (by Fourier transform infrared spectroscopy and grazing incidence X-ray diffraction), the corrosion resistance of the RF-MS coated Mg-0.8Ca substrates was electrochemically tested (in synthetic biological media with different degrees of biomimicry), and their cytocompatibility was assessed in osteoblast and fibroblast cell cultures. By collective assessment, the most promising performances, in terms of mass loss (~7% after 12 days), hydrogen release rate (~6 mL/cm2 after 12 days), electrochemical corrosion parameters and cytocompatibility, were obtained for the crystalline HA coating. [ABSTRACT FROM AUTHOR]

Chitosan is a cationic polymer that forms polymerized membranes upon reaction with anionic polymers. Chitosan−carboxymethyl cellulose (CMC) capsules are drug delivery carrier candidates whose mechanical strength and permeability must be controlled to achieve sustained release. In this study, the capsules were prepared from chitosan−γ-glycidoxypropyltrimethoxysilane (GPTMS)−CMC. The mechanical stability of the capsules was improved by crosslinking the chitosan with GPTMS. The capsules were then coated with hydroxyapatite (HAp) by alternately soaking them in calcium chloride solution and disodium hydrogen phosphate solution to prevent rapid initial drug release. Cytochrome C (CC), as a model drug, was introduced into the capsules via two routes, impregnation and injection, and then the CC released from the capsules was examined. HAp was found to be deposited on the internal and external surfaces of the capsules. The amount of CC introduced, and the release rate were reduced by the HAp coating. The injection method was found to result in the greatest CC loading. [ABSTRACT FROM AUTHOR]

In case of an incident in the nuclear industry or an act of war or terrorism, the dissemination of plutonium could contaminate the environment and, hence, humans. Human contamination mainly occurs via inhalation and/or wounding (and, less likely, ingestion). In such cases, plutonium, if soluble, reaches circulation, whereas the poorly soluble fraction (such as small colloids) is trapped in alveolar macrophages or remains at the site of wounding. Once in the blood, the plutonium is delivered to the liver and/or to the bone, particularly into its mineral part, mostly composed of hydroxyapatite. Countermeasures against plutonium exist and consist of intravenous injections or inhalation of diethylenetetraminepentaacetate salts. Their effectiveness is, however, mainly confined to the circulating soluble forms of plutonium. Furthermore, the short bioavailability of diethylenetetraminepentaacetate results in its rapid elimination. To overcome these limitations and to provide a complementary approach to this common therapy, we developed polymeric analogs to indirectly target the problematic retention sites. We present herein a first study regarding the decontamination abilities of polyethyleneimine methylcarboxylate (structural diethylenetetraminepentaacetate polymer analog) and polyethyleneimine methylphosphonate (phosphonate polymeric analog) directed against Th(IV), used here as a Pu(IV) surrogate, which was incorporated into hydroxyapatite used as a bone model. Our results suggest that polyethylenimine methylphosphonate could be a good candidate for powerful bone decontamination action. [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]

Today, osteoporosis has become a major global health issues. The World Health Organization declares that 320 billion people have osteoporosis now, and more than 1.5 billion osteoporosis traumatic events occur every year. Bones become fragile and fracture risk is high; thus, it is crucial to choose the right biodegradable implants in order to minimize reoperations of patients with systemic osteoporosis. This investigation aimed to carry out a morphological assessment of the state of bone tissue with osteosynthesis of a femoral fracture in rats, using a model of osteoporosis with the installation of magnesium alloy implants coated with hydroxyapatite and sealed with polytetrafluoroethylene. According to this study, the indicators of angiogenesis and bone formation in experimental animals were significantly higher when an implant coated with hydroxyapatite sealed with polytetrafluoroethylene was used, compared to an implant coated only with hydroxyapatite and in rats without an implant. Based on the data obtained, it is possible to consider a magnesium implant coated with hydroxyapatite and sealed with polytetrafluoroethylene as a promising material for fracture therapy in patients with reduced bone density. [ABSTRACT FROM AUTHOR]

• A finite element model for nanosecond laser processing of HA coatings was developed and predict the ablation morphology. • As the number of laser pulses increased, the temperature field shifted from an elliptical to a crescent-shaped distribution. • Due to the low thermal conductivity of the HA coating, the edges of the ablation pits showed no significant raised morphology. In this study a finite element model of nanosecond laser processing was developed using HA coatings on the surface of the biomaterial titanium alloy as the object of study. In this model, the nanosecond laser obeys a Gaussian distribution in time and space. In addition, the effects of material thermal conductivity, thermal convection and thermal radiation on the ablation morphology during the processing were considered in the model. The results showed an elliptical distribution of the temperature field in the initial period under the action of the Gaussian beam, with successive pulses and ablation crater shapes giving a crescent-shaped distribution of the temperature field. The cooling process of the melt pool was mainly influenced by heat conduction, and the depth of the ablation pits increased significantly with the number of ablation, due to the combined effect of vapourisation and liquid phase migration. However, the lower recoil pressure at the ablation edge and the horizontal surface tension resulted in the groove width not increasing significantly with the number of ablation. Due to the lower thermal conductivity of the HA material compared to the metal, the ablation crater edges did not appear to have a raised crater shape and the ablation crater showed a shallow and wide formation. In addition, the simulated plus imitation shell shape was simulated using Soildworks software. The relative error between the simulation depth and the machining depth was small, and the simulated morphology was in good agreement with the experimental data. The validity and reliability of this finite element model was verified and can be used to guide the nanosecond laser processing of HA coatings. [ABSTRACT FROM AUTHOR]

Titanium-niobium-zirconium (TiNbZr) alloys represent a promising class of newly developed titanium-based biomaterials, engineered to exhibit superior properties for biomedical applications. This study investigates the influence of hydroxylated multi-walled carbon nanotubes (MWCNTs) on the surface properties of hydroxyapatite coatings prepared by the plasma electrolytic oxidation (PEO) method for implant applications. The optimal concentration of MWCNTs in the PEO coating was determined based on the superior surface, electrochemical, and biological properties obtained. The incorporation of MWCNTs led to an enhancement in surface roughness from R a 0.06 ± 0.02 to R a 0.618 ± 0.03 µm, improved wettability with a decrease in contact angle from 63.03° ± 1.1–28.29° ± 0.07, and a reduction in elastic modulus from 77.20 ± 2.26 GPa to 54.50 ± 2.22 GPa. Furthermore, electrochemical corrosion resistance analysis revealed an increase in inner passivation resistance up to 2.24 × 10 ×7 Ω.cm2 with the addition of MWCNTs. Antibacterial activity analysis demonstrated that the optimal concentration of MWCNTs resulted in a 3.1-fold and 2.7-fold reduction in E. coli and S. aureus bacteria, respectively, compared to uncoated samples. Cell viability against MC3T3-E1 cells showed a 25 % higher viability with MWCNTs than uncoated substrates. [Display omitted] • MWCNT/HA composite coatings on TiNbZr substrate using the plasma electrolytic oxidation were researched. • TiNbZr exhibits improved favourable elastic modulus, making it a suitable candidate for dental implant applications. • MWCNT/HA composite coatings demonstrate enhanced wettability and corrosion resistance. • MWCNT/HA composite coatings exhibit enhanced biocompatibility and antibacterial activity. [ABSTRACT FROM AUTHOR]

Magnesium alloys are promising candidates for next-generation biodegradable biomaterials. However, their poor corrosion resistance has limited their medical applications. In this study, to improve the bioactivity performance and control the degradation rate of an AZ31 Mg alloy, anodic oxide coatings containing bioactive glass (BG) were created on the alloy using plasma electrolytic oxidation (PEO). First, BG nanoparticles were synthesized through the sol-gel method and surface-modified with polydopamine (BG/PDA). These nanoparticles were then dispersed in an alkaline phosphate electrolyte and incorporated into the coatings grown using unipolar and bipolar waveforms. According to EDS results, incorporation of BG/PDA nanoparticles was higher when the bipolar waveform was applied. Electrochemical impedance spectroscopy revealed that the coatings significantly enhanced the corrosion resistance of the AZ31 Mg alloy, with the BG/PDA nanoparticle-containing coatings demonstrating the lowest degradation rate during long-term immersion. These coatings achieved the highest faradic resistance of ∼ 12 kΩ.cm² after 28 days of immersion. The incorporation of BG and BG/PDA nanoparticles enhanced the bioactivity performance of the coatings, facilitating hydroxyapatite formation on the coating surface. Based on the results, the newly developed BG-coated alloy shows promising potential for biomedical applications. [Display omitted] • BG NPs were inertly entered the craters of PEO coatings in the amorphous structure. • Dopamine treatment of BG NPs enhanced their incorporation esp. at the BP waveform. • BG NPs raised corrosion performance of the coatings at short-term immersion in PBS. • BG/DP NPs improved bioactivity and long-term corrosion performance of the coatings. [ABSTRACT FROM AUTHOR]

• Hydroxyapatite nanoparticles were synthesized utilizing the microemulsion method. • In this synthesis utilized two surfactants with different concentrations of CTAB and a constant amount of DMSO. • Hydroxyapatite coatings in the presence of CTAB were well prepared with smaller particle sizes. • In the presence of surfactants, crack-free and uniform films coated on Ti-6Al-4V with high corrosion resistance. • The coatings prepared with CTAB generated a uniform and ordered array of HAP-NPs with a well-regular spherical shape. Hydroxyapatite nanoparticles (HAP-NPs) were synthesized using a microemulsion (cetyltrimethylammonium bromide (CTAB) and dimethyl sulfoxide (DMSO) as surfactants) method. The influence of the optimum ratios of CTAB concentrations as surfactants in the microemulsion on HAP morphology was investigated. After dispersing the HAP powders, a high-speed spin coating process at 2500 RPM was employed to produce HAP coatings on the Ti-6Al-4V alloy. The HAP-NP properties were characterized using techniques such as XRD, FTIR, FESEM, and AFM. Studies utilizing electrochemical impedance spectroscopy (EIS) in a simulated body fluid (SBF) solution. The corrosion resistance of coated samples compared to bare substrate increased from 67 to 853.34 kΩ cm2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rapid coating of orientation-controlled hydroxyapatite layer on human tooth in 30 s. • Rapid protection and repair of tooth surface in dental practice using hydroxyapatite. • Laser-assisted novel crystallization using viscous light-absorber paste. • The method is applicable to all tissues of tooth using medically approved equipment. • Finding of hydroxyapatite nanofibers as the constituent of enamel, like as bone. Functionalization of teeth surfaces has attracted much attention from the perspective of preventive dentistry. Laser irradiation (30 s) of the viscous light-absorber paste coated on the tooth substrate enabled ultrafast coating of orientation-controlled fluoride-substituted hydroxyapatite (HAP) rod layers, 150–500 nm thick, in a calcium phosphate solution. On enamel, the layers perfectly inherited orientations and structures of the crystals in the substrate, exhibiting two types of hierarchies at different scales. One was a submicron-scale hierarchy, in which an approximately 60-nm-wide rod comprised multiple thinner rods, approximately 20-nm wide, oriented along the c -axis. The 20-nm-wide rods exhibited another type of nanoscale hierarchy comprising incompletely assembled nanofibers < 5-nm wide. In dentin and cementum, c -axis-elongated HAP rods grown on the substrates displayed less arrangement in their elongation direction than those grown on enamel. Most rods on dentin were single crystals, unlike those grown on enamel. On the cementum, each polycrystalline rod (100–150 nm wide) comprised multiple single-crystal rods approximately 60-nm wide, forming a sub-micron hierarchy similar to that observed in enamel. The developed method may be useful in dental practice for protecting teeth surfaces and repairing microdefects in enamel, dentin, and cementum. [ABSTRACT FROM AUTHOR]

Microalgal biomass has shown inspiring potential for the heavy metal removal from wastewater, and forming microalgal biofilm is one of the sustainable methods for the microalgal biomass production. Here we report the formation of microalgal biofilm by accelerated colonization of typical algae Chlorella on thermal sprayed aluminum (Al) coatings with biologically modified surfaces. Micro-patterning surface treatment of the Al coatings promotes the attachment of Chlorella from 6.31 % to 17.51 %. Further enhanced algae attachment is achieved through liquid flame spraying a bioactive crushed oyster shell-hydroxyapatite (CaCO 3 -HA) composite top layer on the micropatterned coating, reaching 46.03–49.62 % of Chlorella attachment ratio after soaking in Chlorella suspension for 5 days. The rapidly formed microalgal biofilm shows an adsorption ratio of 95.43 % and 85.23 % for low concentration Zn2+ and Cu2+ in artificial seawater respectively within 3 days. Quick interaction has been realized between heavy metal ions and the negatively-charged extracellular polymeric substances (EPS) matrix existing in the biofilm. Fourier transform infrared spectroscopy (FTIR) results indicate that both carboxyl and phosphoryl groups of biofilms are crucial in the adsorption of Cu2+ and the adsorption of Zn2+ is due to the hydroxyl and phosphate groups. Meanwhile, the biofilm could act as a barrier to protect Chlorella against the attack of the heavy metal ions with relatively low concentrations in aqueous solution. The route of quick cultivating microalgal biofilm on marine structures through constructing biological layer on their surfaces would give insight into developing new techniques for removing low concentration heavy metal ions from water for environmental bioremediation. • A facile surface coating approach is proposed to promote formation of microalgal biofilm. • Micropatterned Al coating with bioactive top layer greatly promotes Chlorella biofilm formation. • Removal of low concentration Zn2+ and Cu2+ by Chlorella biofilm reaches 95.43 % and 85.23 %. • EPS of Chlorella biofilm is involved in the adsorption of heavy metal ions. • Chlorella biofilm protect the Chlorella within the biofilm against the attack of heavy metal ions. [ABSTRACT FROM AUTHOR]

Ti6Al4V porous scaffolds are designed and fabricated to solve the elastic modulus mismatch between bone and an implant. Bioactive coating is applied on the surface of the implant to improve biocompatibility of titanium implants and form chemical bonds with surrounding bone. Therefore, this study aims to develop a bio-functional coating on Selective Laser Melting (SLM) manufactured porous Ti6Al4V scaffold produced using plasma electrolytic oxidation technique (PEO). Hydroxyapatite (HAp) and fluorapatite (FAp) were formed on the scaffold surface and field emission scanning electron microscopy (FESEM) was used to study the surface morphology and thickness of the coating. The chemical composition of the coatings was investigated by using an energy dispersive spectroscopy (EDS), X-ray diffractometer (XRD), and X-ray photoelectron spectroscopy (XPS). The coating formation was non-homogeneous with Ca/P ratio range of 1.24 to 1.41, approaching ratio of tricalcium phosphate compound. In vitro bioactivity test using a simulated body fluid (SBF) was conducted and the apatite formation on the coating was analyzed. PEO coatings on Ti6Al4V SLM-manufactured porous scaffolds containing fluoride and calcium salt have shown good bioactivity with the apatite formation that can be observed on all coated scaffolds. It was concluded that the combination of bio-functional coating on the surface of the SLM-manufactured porous scaffold provides synergistic effects, which was beneficial in improving the biocompatibility of orthopedic porous metallic implants. Hence, SLM-PEO approach potentially can be adapted to develop a bioactive titanium implant with tunable mechanical properties for orthopedic applications. • The HAp/TiO 2 -based coating was produced on SLM Ti6Al4V porous scaffold by using PEO. • The formation of the PEO coating on the scaffolds is non-homogeneous. • The treatment time and porosity percentage of scaffolds influence the number of pores and their sizes. • The presence of hydroxyapatite enabled apatite formation around the coating. [ABSTRACT FROM AUTHOR]

[Display omitted] The present work reports the adsorption, release, antibacterial properties, and in vitro cytotoxicity of sodium fusidate (SF) associated with a carbonated calcium phosphate bone cement. The adsorption study of SF on cement powder compared to stoichiometric hydroxyapatite and nanocrystalline carbonated apatite was investigated to understand the interaction between this antibiotic and the calcium phosphate phases involved in the cement formulation and setting reaction. The adsorption data revealed a fast kinetic process. However, the evolution of the amount of adsorbed SF was well described by a Freundlich-type isotherm characterized by a low adsorption capacity of the materials toward the SF molecule. The in vitro release results indicated a prolonged and controlled SF release for up to 34 days. The SF amounts eluted daily were at a therapeutic level (0.5–2 mg/L) and close to the antibiotic minimum inhibitory concentration (0.1–0.9 mg/L). Furthermore, the release data fitting and modeling suggested that the drug release occurred mainly by a diffusion mechanism. The antibacterial activity showed the effectiveness of SF released from the formulated cements against Staphylococcus aureus. Furthermore, the biological in vitro study demonstrated that the tested cements didn't show any cytotoxicity towards human peripheral blood mononuclear cells and did not significantly induce inflammation markers like IL-8. [ABSTRACT FROM AUTHOR]