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Hydroxyapatite (HAp), resembling human bone tissue, is a promising biomaterial for dental and hip prosthetics. Incorporating fluorine ions enhances HAp properties, particularly in dental restoration. This new study examines the physicochemical and biological properties of fluorine substituted hydroxyapatite (FHAp) coatings. Structural and morphological properties of the coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The elemental composition of the FHAp coatings was studied using energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy. Fourier Transform Infrared spectroscopy (FTIR) investigations were also conducted. The typical peaks identified in XRD patterns of the FHAp were associated with pure hydroxyapatite with hexagonal structure. The general XPS spectrum of FHAp coatings shows peaks corresponding to the constituent elements of stoichiometric HAp as well as the presence of F that was used as a substituent. Consequently, the FTIR studies results underlined the presence of hydroxyapatite in the FHAp coatings. The SEM images reveal the presence of a uniform and continuous layer of particle conglomerates evenly distributed across the FHAp surface. Valuable information about the FHAp coating's wettability, adhesion and coating thickness were also obtained. Also, the AFM images suggest the absence of the significant irregularities from the surface of the FHAp coatings. Investigations of FHAp coatings reveal promising outcomes for cell viability and proliferation. Detailed analysis of FHAp's 3D surface characteristics and roughness, following ISO 25178–2:2012 standards, highlights their favorable biocompatibility, supporting MG63 cell proliferation. The surface roughness parameters of FHAp coatings were found to vary, with Sa values spanning from 0.029 ± 0.004 μm to 0.778 ± 0.007 μm, while Sq ranged from 0.035 ± 0.005 μm to 0.907 ± 0.011 μm. Furthermore, FHAp exhibits skewness (Ssk) from −0.048 ± 0.006 to 0.195 ± 0.009, kurtosis (Sku) from −0.600 ± 0.011 to −1.050 ± 0.021, and fractal dimension from 2.14 ± 0.01 to 2.19 ± 0.01, indicating consistent surface complexity and favorable properties. The Minkowski Functionals mirror the morphological observations from AFM images, emphasizing their dynamic influence on the samples' surfaces. • Atomic Force Microscopy (AFM) was used to analyze the surface topography of FHAp coatings and MG63 cell adhesion on FHAp coatings surface. • FHAp coatings displayed uniform deposition with evenly distributed particle conglomerates. • MG63 cells maintained normal morphology and adhered consistently to FHAp coatings over 72 h. • AFM imaging revealed a monolayer of well-aligned cells on FHAp coatings, suggesting good biocompatibility. • FHAp coatings offer promising surfaces for MG63 cell adherence and proliferation. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) is an engineered biomaterial that closely resembles the hard tissue composition of humans. Biological HA is commonly non-stoichiometric and features lower crystallinity and higher solubility than stoichiometric HA. The chemical compositions of these biomaterials include calcium (Ca), phosphorus (P), and trace amounts of various ions such as magnesium (Mg2+), zinc (Zn2+), and strontium (Sr2+). Significantly, these ions are essential for the metabolic processes of hard tissues. This study involved the application of Co2+-doped HA coatings at different concentrations (5%, 10%, and 20% by weight) onto Ti-6Al-4V, utilizing the spin-coating method. The FTIR, XRD, FESEM, EDS, and AFM techniques were utilized to analyze the coated substrates. Tetraethyl orthosilicate (TEOS (T)) was employed as a binding agent to enhance adhesion and reduce surface cracks in the coating. The adhesion strength of coatings applied to Ti-6Al-4V was assessed for use in biomedical applications. Polarization and electrochemical impedance spectroscopy (EIS) studies in a simulated body fluid (SBF) solution were conducted to evaluate the corrosion behavior of the coatings. The corrosion behavior of the coated samples increased significantly compared to the substrate. The 10Co/HA/T coating demonstrated the highest charge transfer resistance (Rct) value of 13.40 MΩ × cm2, whereas the uncoated substrate exhibited the lowest Rct of 0.14 MΩ × cm2. A cell viability assay was conducted utilizing MG-63 cells for the Ti-6Al-4V and coatings, which prepared coatings demonstrated outstanding biocompatibility. Based on this study, the 10Co/HA/T coating was identified as the most promising sample. These findings suggest that surface modification of Ti-6Al-4V through Co2+-doped HA coatings offers a viable strategy for enhancing its performance in biomedical applications. [ABSTRACT FROM AUTHOR]

A wireless soil pH sensor is proposed using a sheet‐type perfect absorber metamaterial. The sensor utilizes a high‐impedance surface metamaterial, which functions as a perfect absorber at the resonant frequency. This sensor has a uniform water‐soluble Mg film at the bottom coated with hydroxyapatite that degrades depending on the pH, and a periodic square split ring resonator metamaterial structure made on top of a lossy dielectric plate. The sensor detects the dissolution of the metamaterial due to soil pH conditions through the electromagnetic wave reflection response at GHz frequency. Because of the perfect absorbing characteristics, the influence of soil on the metamaterial's electromagnetic response is blocked, allowing for robust measurement regardless of soil type. By coating the Mg with hydroxyapatite, the difference between acidic (pH = 3.0) and neutral soils can be detected by the time difference by a factor of three in the reflectance change from 40% to 75% reflectance change, indicating a transition from absorptive to reflective of the metamaterial's response, at the resonant frequency of 4.12 GHz. [ABSTRACT FROM AUTHOR]

Tooth loss replacement using dental implants is becoming more frequent. Traditional dental implant materials such as commercially pure titanium and titanium aluminum vanadium alloys have well-proven mechanical and biological properties. New titanium alloying metals such as niobium provide improved mechanical properties such as lower elastic modulus while displaying comparable or even better biocompatibility. Hydroxyapatite coatings are a well-documented and widely used method for enhancing dental implants' surface characteristics and properties and could provide a useful tool for further enhancing titanium–niobium implant properties like osteointegration. Among several coating techniques, physical deposition methods and, in particular, vapour deposition ones are the most used due to their advantages compared to wet deposition techniques for hydroxyapatite coating of metallic surfaces like that of dental implants. Considering the scarcity of data concerning the in vivo evaluation of titanium–niobium biocompatibility and osteointegration and the lack of studies investigating coating these new proposed alloys with hydroxyapatite, this review aims to further knowledge on hydroxyapatite-coated titanium niobium alloys. [ABSTRACT FROM AUTHOR]

Featured Application: Magnesium-doped carbonated hydroxyapatite and tricalcium phosphate anodized coatings are applied in alpha, beta, and duplex titanium alloys to improve osseointegration. The rising demand for dental and orthopedic implants and their frequent aseptic loosening failure mode necessitate the drive to continue modifying implant surfaces to improve osseointegration outcomes. Plasma-sprayed hydroxyapatite coatings are widely used but are prone to delamination. This study involves a single-step anodization process utilizing a novel electrolyte to produce Mg-doped carbonated hydroxyapatite and tricalcium phosphate-containing coatings on four titanium alloy surfaces. XRD confirmed hydroxyapatite and tricalcium phosphate formation, with FTIR examination revealing carbonate substitutions indicative of bone-like apatite formation in each oxide. SEM analyses revealed micro- and nano-scaled surface features on each oxide. SEM and EDS analyses of the oxide coating cross-sections showed each group to be bi-layered with an inner titanium dioxide-rich layer and an outer hydroxyapatite/tricalcium phosphate-rich layer. The oxide layer adhesion quality was shown to be good on CPTi, TAV, and TiMo α + β implant alloy surfaces. Unfortunately, the anodization process also resulted in an undesirable and embrittling omega phase at the substrate–oxide interface due to the migration of molybdenum into the inner oxide. Nonetheless, the anodized coatings on the CPTi and TAV alloy substrates, which are the most widely used titanium alloys for implant applications, show much potential for improving future patient outcomes. [ABSTRACT FROM AUTHOR]

Infections are a common post-operative ailment for patients who have received a dental implant or device and can be attributed to biofilm formation in tissue or on the implant. Many current solutions for oral hygiene have side effects and affect the natural oral microbiome. 2-heptylcyclopropane-1-carboxylic acid (2CP) is a medium-chain fatty acid and synthetic diffusible signaling factor that can prevent and disperse biofilm. The purpose of this work was to evaluate an immersion strategy for coating hydroxyapatite (HAp) with 2CP to prevent biofilm attachment on and around natural teeth and dental implants. The release profile of 2CP-loaded and 2CP+oral rinse-loaded HAp coupons (n = 6) was assessed by a 3-day exposure to phosphate buffered saline (PBS). Antimicrobial properties against Porphyromonas gingivalis and cytocompatibility of 2CP-loaded HAp coupons (n = 4) were also assessed alone and in combination with 0.12% chlorhexidine gluconate oral rinse. The majority of 2CP is released by 12 h. 2CP, oral rinse, and 2CP+oral rinse significantly reduced P. gingivalis viability, though direct contact assay demonstrates a significant reduction in Saos-2 viability for oral rinse and 2CP+oral rinse coupons. Immersion or rinsing hydroxyapatite with 2CP could inhibit biofilm-associated dental infections and prevent further complications including caries, gingivitis, and peri-implantitis. [ABSTRACT FROM AUTHOR]

316L stainless steel (316L SS) is an excellent implant material because of its durability, low modulus, superior corrosion resistance, and biocompatibility. However, 316L SS was bioinert and cannot be combined with living tissue. To cover this weakness, 316L SS needs to be coated with a material that has high bioactivity, such as hydroxyapatite (HA) bioceramic. Flame spray deposition (FSD) is a promising method for applying hydroxyapatite to 316L SS, but the deposition product's low interfacial adhesion makes it brittle. This study recommends preheating the substrate (300, 600, and 900) C to improve the adhesive bond before coating it with hydroxyapatite. The coated 316L SS product was then subjected to mechanical testing and analytical techniques (XRD and SEM/EDX) to evaluate its osseointegration, microstructures, and adhesive strength. After preheating to 900°C, the resulting coated steel showed a significant increase in adhesion strength. The crystallinity index also increased to 99.35%. However, the porosity and layer thickness decreased. The current work can shed light on the coating procedure for stainless steel, which is a promising material for implants, and it can also guide future investigations into the potential uses of HA made from mussel wastes. [ABSTRACT FROM AUTHOR]

Numerous papers have been reported on surface treatment of metallic implant to facilitate positive interaction between the implant and hard tissue interface. In this paper, surface treatment such as chemical etching was done on the biomedical grade cobalt‐based alloy prior to hydroxyapatite coating deposition to enhance its biocompatibility. The objective is to investigate which temperature possesses the positive effect in adhesion strength of hydroxyapatite coating without detrimental the surface hardness. Observation showed that acid etched at the highest temperature (80 °C) has successfully roughen the substrate surface from 0.168 μm ±0.1 μm to 1.383 μm ±0.2 μm. Vickers hardness measurement on surface treated at 80 °C exhibit an increment of surface hardness which is about 39 % compared to surface treated at lower temperature. The highest thickness of hydroxyapatite coating layer (~57 μm) was evidently formed on the substrate etched at 80 °C with minimal cracks and no delamination. This phenomenon happened due to chemical reaction were rigorously attack on the substrate surface have provide more micro‐pits, pores and deeper craters that trap more efficiently of hydroxyapatite particles for thicker and dense coating formation. It is worth to note that too long acid soaking will also detrimental the material properties. [ABSTRACT FROM AUTHOR]

Hydroxyapatite/bone powder composite coatings on ZX504 alloy have been developed using the sol–gel process and their corrosion behavior has been explored. The alloy was anodized in 1 M NaOH + 0.5 M Na2SiO3 solution. An 0.5 P2O5 + z 1.67 Ca(NO3)2.4H2O solution with 10 g/L, 20 g/L, and 30 g/L bone powder concentrations and 50 s, 100 s, and 150 s dip-coating durations, followed by calcination at 400°C, was used to develop the coatings. Microscopic analysis results disclosed the formation of a uniform and highly porous MgO film on the alloy to guarantee the subsequent coating adhesion. The results also confirmed the fruitful formation of smoother hydroxyapatite + bone powder composite coatings on the film. Electrochemical corrosion tests revealed that the alloy exhibited the lowest corrosion resistance, while the hydroxyapatite + 30 g/L bone powder composite-coated alloy possessed the best performance with a significantly low corrosion rate of 0.07 mm/year, suggesting the composite-coated alloy is a desired candidate for implant application. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAp)-coated bone implants are frequently used for orthopaedic or dental implants since they offer high biocompatibility and osteoconductivity. Yet, problems such as infections, e.g. periprosthetic joint infections, occur when implanting foreign material into the body. In this study, HAp coatings were produced via high-velocity suspension flame spraying (HVSFS). This method allows for the production of thin coatings. We investigated the effects of different gas parameters on the coating properties and on the biocompatibility, which was tested on the human osteosarcoma cell line MG63. Furthermore, Copper (Cu) was added to achieve antibacterial properties which were evaluated against standard microorganisms using the airborne assay. Three gas parameter groups (low, medium, and high) with different Cu additions (0 wt.%, 1 wt.% and 1.5 wt.%) were evaluated. Our findings show that porosity as well as hardness can be controlled through gas parameters. Furthermore, we showed that it is possible to add Cu through external injection. The Cu content in the coating as well as the release varies with different gas parameters. Both antibacterial efficacy as well as biocompatibility are affected by the Cu content. We could significantly reduce the amount of colony-forming units (CFU) in all coatings for E. coli, CFU for S. aureus was reduced by adding 1.5 wt.% of Cu to the coating. The biocompatibility testing showed a cytotoxicity threshold at a Cu-release of 14.3 mg/L in 120 hours. Based on our findings, we suggest medium gas parameters for HVSFS and the addition of 1 wt.% Cu to the coating. With these parameters, a reasonable antibacterial effect can be achieved while maintaining sufficient biocompatibility. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) or bioceramic-based coatings on stainless steel (SS) 316L significantly enhance the biofunctionality of the base material's surface. However, HA's low thermal conductivity and brittleness limit its effectiveness as a coating material. This study investigates HA coating on SS 316L using electric discharge machining (EDM) with varying discharge energies and powder concentrations. Surface morphology, elemental composition, and phase analysis of untreated and coated samples were characterised using field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD). The results demonstrate that the HA-assisted EDM process creates a coating comprising biocompatible oxides, phosphates, carbides, and intermetallic compounds. The coating exhibits a thin resolidified layer of 10.74 μm, characterised by redeposited spherical debris, shallow cavities, and a surface texture of 2.688 μm. The layer's hydrophilic nature is confirmed by a minimum contact angle of 47.68°. Taguchi analysis indicates that the machining rate is optimised at an HA powder concentration of 16 g/l, with peak current and HA powder concentration being the most influential parameters affecting resolidified layer thickness, surface texture, and wetting angle. The research intends to motivate SS 316L medical device manufacturers to implement the HA-assisted EDM process for bioimplant's dual machining and coating. [ABSTRACT FROM AUTHOR]

Biomedical coatings were elaborated by pulsed electrodeposition with hydrogen peroxide (H 2 O 2) into electrolytes on Ti 6 Al 4 V substrates, and the effect of H 2 O 2 concentration on the electrolyte and the heat treatment was studied. The experimental procedures employed in this study produce a consistent hydroxyapatite coating. This coating is well-suited for use in bio-implants, as it enhances the integration of the implant with surrounding bone tissue and improves the mechanical performance. The coatings' surface morphology and chemical composition were assessed using scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDXS) for x-ray microanalysis. X-ray diffraction (XRD) was also utilized to identify the phases and composition of the coatings. Nanoindentation and scratch tests were conducted to analyze the nanomechanical properties and adhesion behavior. Potentiodynamic polarization was employed in the Ringer solution to evaluate the corrosion resistance and replicate the conditions of the human body environment. The results of our thorough investigation revealed that employing pulsed electrodeposition with 9 % H 2 O 2 in the electrolyte, combined with subsequent heat treatment, facilitated the creation of coatings comprising two distinct phases: stoichiometric hydroxyapatite (HAP) and β-tricalcium phosphate (β-TCP). Our meticulous research underscores the significance of this process in achieving these specific coating compositions. Under these tests listed above, this composite demonstrated favorable mechanical properties (E = 30.45 GPa and H = 72.2 MPa). It also exhibited superior scratch adhesion and a critical load of 23 MPa and 12 N, respectively. Additionally, an improvement in tribological comportment was observed, and the wear volume decreased from 4.15 106 μm3 to 2.44 106 μm3. The HAP coating heat treated with 9 % H 2 O 2 exhibited the highest corrosion resistance, with E corr at −0.189 V/SCE and i corr at −1.11 μA cm−2 [ABSTRACT FROM AUTHOR]

[Display omitted] Stone-built cultural heritage faces threats from natural forces and anthropogenic pollutants, including local climate, acid rain, and outdoor conditions like temperature fluctuations and wind exposure, all of which impact their structural integrity and lead to their degradation. The development of a water-based, environmentally-friendly protective coatings that meet a combination of requirements posed by the diversity of the substrates, different environmental conditions, and structures with complex geometries remains a formidable challenge, given the numerous obstacles faced by current conservation strategies. Here we report the structural, electrical, and mechanical characterization, along with performance testing, of a nanostructured hydrophilic and self-healing hybrid coating based on hydroxyapatite (HAp) nanocrystals and polyelectrolyte multilayers (PEM), formed in-situ on Greek marble through a simple spray layer-by-layer surface functionalization technique. The polyelectrolyte-hydroxyapatite multilayer (PHM) structure resembled the design of naturally forming trabecular bone, attained at a short procedural time. It exhibited chemical affinity, aesthetical compatibility and resistance to weathering while offering reversibility. The proposed method is able to generate micron-sized coatings with controlled properties, such as adhesion and self-healing, leading to less weathered surfaces. Our results show that the PHM is a highly effective protective material that can be applied for stone protection and other similar applications. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF) is one of ideal reinforcements to hydroxyapatite (HA) owing to its unique structure, excellent biocompatibility and high mechanical properties. However, the mechanical property of CF reinforced HA (CF/HA) composites cannot be effectively improved due to the mismatch in surface properties and thermal expansion coefficients between CF and HA. In order to solve the problems, nano-hydroxyapatite (nHA) coating with different thickness was fabricated on the CF surface. The effect of the coating thickness on mechanical property of nHA-coated CF/HA composites was studied by finite element analysis. The CF with proper nHA coating thickness was subsequently used to reinforce HA. The compressive strength of nHA-coated CF/HA composites was approximately 97.3 % and 164.6 % higher than those of the uncoated CF/HA composites and pure HA ceramics, respectively. The interface properties and crack propagation were analyzed by cohesive element in the finite element analysis. The toughening mechanism of the composites included interfacial debonding, crack deflection, crack branching, and crack bridging. The mechanical properties of nHA-coated CF/HA composites were enhanced due to the strong interfacial bonding strength and reducing cracking in HA matrix. The prepared nHA-coated CF/HA composites satisfy the requirement of the mechanical properties of human load-bearing bone. It can be used to prepare cages, plates, screws, pins and other compact bone substitute parts in bone grafting. The study provided a method for construction of nHA-coated CF/HA composites with the designed properties by adjusting the nHA coating on the fiber and can be used to design other fibers reinforced ceramic matrix composites. [Display omitted] [ABSTRACT FROM AUTHOR]

The purpose of coatings is to protect or enhance the functionality of the substrate material, irrespective of the field in which the material was designed. The use of coatings in medicine is rapidly expanding with the objective of enhancing the osseointegration ability of metallic materials such as titanium. The aim of this study was to obtain biomimetic hydroxyapatite (HAp)-based coatings on titanium by using the pulsed galvanostatic method. The morphology of the HAp-based coatings revealed the presence of very thin and wide plate-like crystals, grown perpendicular to the Ti substrate, while the chemical composition highlighted a Ca/P ratio of 1.66, which is close to that of stoichiometric HAp (1.67). The main phases and chemical bonds identified confirmed the presence of the HAp phase in the developed coatings. A roughness of 228 nm and a contact angle of approx. 17° were obtained for the HAp coatings, highlighting a hydrophilic character. In terms of biomineralization and electrochemical behavior, it was shown that the HAp coatings have significantly enhanced the titanium properties. Finally, the in vitro cell tests carried out with human mesenchymal stem cells showed that the Ti samples coated with HAp have increased cell viability, extracellular matrix, and Ca intracellular deposition when compared with the uncoated Ti, indicating the beneficial effect. [ABSTRACT FROM AUTHOR]

The potential of silver-containing hydroxyapatite (Ag-HA) coatings to prevent orthopaedic implant-associated infection was explored previously; however, the resistance of Ag-HA coatings to late-onset orthopaedic infections is unknown. This study aimed to evaluate the long-term Ag+ elution and antibacterial properties of the Ag-HA coatings through in vitro and in vivo experiments. Ag-HA-coated disc specimens were immersed in fetal bovine serum (FBS) for six months. Ag concentration was measured over time using inductively coupled plasma-mass spectrometry to evaluate Ag release. The hydroxyapatite (HA)- or Ag-HA-coated disc specimens were immersed in FBS for 3 months to elute Ag+ for in vitro experiments. Methicillin-resistant Staphylococcus aureus (MRSA) suspensions were inoculated onto each disc; after 48 h, the number of colonies and the biofilm volume were measured. HA- or Ag-HA-coated disc specimens were inserted under the skin of Sprague-Dawley rats for three months for in vivo experiments. In in vivo experiment 1, specimens were inoculated with MRSA and the number of colonies was counted after 48 h. In in vivo experiment 2, the specimens were inoculated with bioluminescent S. aureus Xen36 cells, and bioluminescence was measured using an in vivo imaging system. The Ag-HA-coated disc specimens continued to elute Ag+ after six months. The biofilm volume in the Ag-HA group was lower than in the HA group. In in vitro and in vivo experiment 1, the bacterial counts in the Ag-HA group were lower than those in the HA group. In in vivo experiment 2, the bioluminescence in the Ag-HA group was lower than that in the HA group on days 1–7 after inoculation. The Ag-HA-coated discs continued to elute Ag+ for a long period and exhibited antibacterial activity and inhibition of biofilm formation against S. aureus. The Ag-HA coatings have the potential to reduce late-onset orthopaedic implant-associated infections. [ABSTRACT FROM AUTHOR]

The process of osteointegration depends significantly on the surface roughness, structure, chemical composition, and mechanical characteristics of the coating. In this regard, an important direction in the development of medical materials is the development of new techniques of surface modification and the creation of bioactive ceramic coatings. Calcium-phosphate materials based on hydroxyapatite have been proposed as bioactive ceramic coatings on titanium implants for the effective acceleration of bone tissue healing. To obtain bioactive ceramic coatings, pulse power sources are best suited, namely detonation spraying, in which the energy of the explosion of gas mixtures is used as a source of pulse action. The pulse mode of operation in the detonation spraying method is preferable for the formation of bioactive ceramic coatings. It provides a high velocity of hydroxyapatite particles, which promotes their effective fixation on the titanium substrate, while minimizing the heating of the material. This approach preserves the substrate structure and improves the coating adhesion. Four different types of coatings with varying O2/C2H2 molar ratios, ranging from 2.6 to 3.7, were obtained using detonation spraying. Powders and obtained coatings of hydroxyapatite were studied by Raman spectroscopy and XRD structural analysis. The results of XRD phase analysis showed the partial conversion of the hydroxyapatite phase to the α-tricalcium phosphate (α-TCP) phase during the detonation spraying process. The results obtained by Raman spectroscopy indicate that hydroxyapatite is the main phase in coatings. All hydroxyapatite-based coatings exhibited hydrophobic properties, which was confirmed by contact-angle values above 90° in wettability tests, characteristic of hydrophobic surfaces. The adhesive strength of the coatings was measured by the scratch test method. Tribological tests were conducted using the ball-on-disk method under both dry conditions and in Ringer's solution. This approach enabled the evaluation of wear resistance and friction coefficient of the coatings in different environments, simulating both lubrication-free conditions and those resembling physiological environments. [ABSTRACT FROM AUTHOR]

BACKGROUND: There are some problems such as bone fusion failure or peri-implant infection after implantation of pure titanium implants. Therefore, surface improvement of titanium implants has become a hot topic in research. Macrophages are an immune defense line of the body in response to external stimuli, and the relevant immune response of any biomaterials implanted in the body is related to macrophages. OBJECTIVE: The graphene oxide/hydroxyapatite composite coating on titanium alloy surface was prepared by electrochemical deposition method. The surface characteristics of the coating and the growth and polarization of macrophage RAW264.7 on the surface were analyzed. METHODS: The graphene oxide coating and graphene oxide/hydroxyapatite composite coating on titanium alloy surface was prepared by electrochemical deposition method. The physical properties of the coating were characterized. Pure titanium sheets (blank group), titanium sheets deposited with pure GO coating (control group) and titanium sheets deposited with graphene oxide/hydroxyapatite composite coating (experimental group) were co-cultured with macrophages RAW264.7, respectively. Cell proliferation was detected by CCK-8 assay and DAPI staining. Cell adhesion on the surface of titanium was observed by scanning electron microscopy, and cell polarization phenotype was detected by flow cytometry. RESULTS AND CONCLUSION: (1) Under scanning electron microscope, the pure titanium sheet showed directional scratches and a few punctate pits. After the pure graphene oxide coating was deposited, the surface of titanium sheet showed more cracks, gullies and particles of uneven size, and the wrinkle-like structure characterized by graphene oxide. After the composite coating was deposited, the surface of the titanium sheet was smooth, and the pellet size was more uniform. The water contact angle of composite coated titanium sheet was lower than that of pure titanium sheet and pure graphene oxide coated titanium sheet (P < 0.05). (2) CCK-8 assay and DAPI staining showed that compared with the blank group and the control group, the cell proliferation in the experimental group was faster. Scanning electron microscopy showed that RAW264.7 cells all adhered to the surface of the three groups of titanium sheets. With the extension of culture time, cell morphology changed from round to spindle shape. After 7 days of culture, cells in the blank group extended short and few pseudopods; cells in the control group extended long and more pseudopods, and cells in the experimental group extended short and more pseudopods, and the overall cell fullness in the experimental group was the best. Flow cytometry results showed that the cells in the experimental group showed a higher proportion of M2 polarization in the anti-inflammatory direction. (3) These findings conclude that graphene oxide/hydroxyapatite composite coating has good physical, chemical, and biological properties. [ABSTRACT FROM AUTHOR]

Objectives: The primary objective of this study is using an anodizing intermediate layer to improve corrosion resistance and adhesion of hydroxyapatite coated AZ31 alloy for applications in biodegradable implants. Methods: An anodizing intermediate layer was formed on the surface of AZ31 substrate at various anodizing voltage of 10, 20, 30, and 40 V respectively by anodizing process. HAp was grow on the surface of AZ31 substrate at 90°C and pH solution of 7.5 by chemical solution treatment method for 2 h. The coated samples were evaluated their corrosion behavior by Electrochemical measurements and biodegradation behavior by immersion test in Hank's balanced salts solution (HBSS) for 28 days via amount of Mg2+ ion released. While, their adhesion strength were evaluated by pull-off method. The amount of Mg2+ ions released of the samples was quantified by the Inductively coupled plasma mass spectrometry. Results: An anodizing intermediate layer was successfully synthesized at various voltages by anodizing process and HAp coatings were prepared by chemical solution treatment method. The corrosion rate of hydroxyapatite coated AZ31 alloy with an anodizing intermediate layer decreased 4.4 times, while adhesion strength increased about two times compared to the HAp coated AZ31 specimen without an anodizing layer and achieved ~14.70, ~6.92 MPa, respectively. After immersion test in HBSS, the adhesion strength of HAp/AZ31-HBSS-specimen decrease to 45% because of large corroded areas with depth holes of hundreds of micrometers. The slighter decrease in adhesion strength of HAp/30V/AZ31-HBSS-specimen to 22% is due to the contribution of the anodizing intermediate layer. Conclusion: HAp coated AZ31 alloy specimen with the existence of a porous structure with an elliptical shape, uniform and high density of MgO on the surface at anodizing voltage of 30 V resulted in a significant increase in corrosion resistance and the adhesion strength of HAp coatings. [ABSTRACT FROM AUTHOR]

The fabrication of hydroxyapatite (HAP)/MgO composite coatings on Mg alloy is crucial for enhancing the corrosion resistance and biocompatibility of biomedical implants. In this study, we aimed to investigate the effects of two different surface modification methods, i.e., electrochemical (electrodeposition, ED) and chemical (solution treatment, ST), on the phase structure, degradation properties, and biocompatibility of the composite coatings in comparison to the anodized coating. The surface morphologies and crystalline structures of the coatings were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Subsequently, the degradation rate of the coatings in simulated body fluid were comprehensively evaluated by using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electrochemical microscopy (SECM) tests. Additionally, in-vitro cell proliferation assays were employed to quantitatively assess the biocompatibilities of the coatings. The results showed that both ED and ST methods were effective in depositing HAP on anodized Mg alloy, resulting in different surface morphologies with hydroxyapatite layer thicknesses of 2.71 μm and 3.56 μm, respectively. In this way, the HAP-deposited coatings exhibited improved corrosion resistances and biocompatibilities compared with those of the anodized coating. Specifically, the ST-deposited composite film displayed superior degradability and biocompatibility which was attributed to its filiform surface morphology and thicker HAP layer. Overall, the present study demonstrates the potential of HAP/MgO composite coatings for biomedical applications, with implications for the development of advanced implant materials with improved performance and biocompatibility. [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]

Due to its similar Young's modulus to bone, polyetheretherketone (PEEK) shows potential as an alternative to metallic implants, avoiding the stress-shielding effect. Hydroxyapatite (HAp) coatings promote bone growth on the implant surface, while zinc oxide acts as an antibacterial agent. This study aims to develop functional coatings on PEEK that simultaneously stimulate bone growth and exhibit antibacterial properties. ZnO-doped HAp coatings were applied to PEEK using a powder mixture of ZnO/HAp and hybrid process (atmospheric plasma spraying and solution precursor plasma spraying). With powder mixtures, the ZnO content in the coatings could be determined without phase change, with nearly half of the initial ZnO powder lost. Meanwhile, using hybrid methods, the aerosol precursor zinc nitrate couldn't fully convert into zinc oxide, resulting in the presence of intermediate zinc hydroxynitrate (up to 39.38%) in the as-sprayed coatings. Subsequently, the zinc hydroxynitrate could be converted to zinc oxide after heat treatment. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) coatings on titanium substrates are widely investigated for biomedical applications due to their biocompatibility and osteoconductivity. This study explores the impact of HA powder particle size on the mechanical and electrochemical properties of flame-sprayed coatings. HA powders were synthesized via a wet chemistry method and characterized using x-ray diffraction, FTIR, and scanning electron microscopy. Flame spraying was employed to deposit HA coatings of varying particle sizes (0-37 µm, 37-63 µm, 63-104 µm, and 104-125 µm) onto titanium substrates. Mechanical properties such as surface roughness, adhesion strength, wear resistance, and Vickers hardness were evaluated, revealing that coatings with smaller particle sizes exhibited smoother surfaces, higher adhesion strengths, superior wear resistance, and greater hardness. Electrochemical properties were assessed through potentiodynamic polarization and electrochemical impedance spectroscopy in simulated body fluid, demonstrating that coatings with finer particle sizes displayed enhanced corrosion resistance compared to those with larger particles. Overall, this study underscores the critical role of HA powder particle size in optimizing the performance of flame-sprayed HA coatings for biomedical applications. [ABSTRACT FROM AUTHOR]

Additive manufacturing has revolutionized implantology by enabling the fabrication of customized, highly porous implants. Surface modifications using electrochemical methods can significantly enhance the bioactivity and biocompatibility of biomaterials, including 3D-printed implants. This study investigates novel coatings on 3D titanium (Ti) samples. Mesh Ti samples were designed and subjected to plasma electrolytic oxidation (PEO) to form a calcium phosphate coating. Subsequently, a layer of polydopamine (PDA) was applied. The electrochemical properties and morphology of the coatings were analyzed. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) revealed well-developed coatings containing calcium phosphates (including hydroxyapatite), titanium dioxide, and polymerized dopamine, suggesting promising bioactive potential. Composite layers incorporating PDA exhibited superior protective properties compared to base PEO coatings. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA, Ca10(PO4)6(OH)2) composite coatings added in the second phase could improve the mechanical properties and bonding strength. The cold spraying technique, as a technology for the deposition of solid particles at low temperatures, is employed to deposit HA ceramic composite coatings. The nano HA material possesses characteristics that enhance properties and promote interface bonding. Due to the exceptional mechanical properties of Ti material, adding Ti particles could improve the mechanical properties of nano HA/Ti composite coatings. In order to explore the deposition deformation mechanism of composite particles under different cold spraying conditions, numerical simulation and experimental testing of deposition behaviors of dual nano HA/Ti composite particles were analyzed. As the particle velocity increased from 400 m/s to 800 m/s in the numerical simulation analysis, the more serious the deposition deformation. Meanwhile, more cracking and splashing phenomena occurred on the surface of the particle. By analyzing the stress value curve of Ti and HA units under different particle velocities, it was found that the adiabatic shear instability phenomenon occurred during the particle deposition on the substrate. In addition, the degree of particle deformation increased with the decrease in the particle size. The results of the experimental investigation were consistent with that of the numerical simulation. [ABSTRACT FROM AUTHOR]

The deposition of agglomerated hydroxyapatite (HAp) powders by low-pressure cold spray has been a topic of interest in recent years. Key parameters influencing the deposition of HAp powders include particle morphology and impact kinetic energy. This work examines the deposition of HAp powders on various metal surfaces to assess the impact of substrate properties on the formation of HAp deposits via cold spray. The substrates studied here encompass metals with varying hardness and thermal conductivities, including Al6061, Inconel alloy 625, AISI 316 stainless steel, H13 tool steel, Ti6Al4V, and AZ31 alloy. Single-track experiments offer insights into the initial interactions between HAp particles and different substrate surfaces. In this study, the results indicate that the ductility of the substrate may enhance HAp particle deposition only at the first deposition stages where substrate/particle interaction is the most critical factor for deposition. Features on the substrate associated with the first deposition sprayed layer include localized substrate deformation and the formation of clusters of HAp agglomerates, which aid in HAp deposition. Furthermore, after multiple spraying passes on the various metallic surfaces, deposition efficiency was significantly reduced when the build-up process of HAp coatings shifted from ceramic/metal to ceramic/ceramic interactions. Overall, this study achieved agglomerated HAp deposits with high deposition efficiencies (30–60%) through single-track experiments and resulted in the preparation of HAp coatings on various substrates with thickness values ranging from 24 to 53 µm. These coatings exhibited bioactive behavior in simulated body fluid. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) has been widely used for coating metal bone implants. However, HA coating may separate from the metal substrates, resulting in poor performance such as inflammatory reactions which may finally lead to implant failure. Dispersing HA into metal substrate may be a viable solution but such a composite may suffer from inferior mechanical strength. Therefore, a functionally graded material (FGM) with HA dispersing in metal substrate in gradients is introduced to increase surface osteogenic capability and simultaneously maintain a good mechanical strength of the bone implant. In this study, Ti6Al4V(Ti64)-HA composite with different component of HA and their corresponding FGMs were fabricated by selective laser melting (SLM). It was demonstrated that compared with the pure Ti64 and Ti64-2.5%HA composite, Ti64-1%HA composite seemed to have a better osteogenic promoting property in vitro. Both the FGMs significantly promoted the osteogenic activities of the pure Ti64 in vivo. Moreover, functionally graded structure improved the anti-compression properties of composites. [ABSTRACT FROM AUTHOR]

This paper introduced the temperature-controlled thermal decomposition method to provide unique nanostructured TeO2-SeO2-HAp coatings on Ti substrates. The mechanical and biological studies, including anti-bacterial and non-cytotoxic properties, are established under various simulated scenarios. In vitro, results indicated that the TeO2-SeO2-HAp coating has excellent adhesion strength and bioactivity. In addition, introducing nano TeO2-SeO2-HAp coatings inhibits the growth of gram-positive bacteria (Staphylococcus aureus) and gramnegative bacteria (Escherichia coli), without resorting to antibiotics. TeO2-SeO2 samples have only 75.99 % inflammation at 200 µg/mL and show excellent anti-inflammatory properties. The TeO2-SeO2-HAp coating reasonably showed good in vitro anti-bacterial as well as antiinflammatory properties with no significant reduction in cell viability, i.e., at lower dosages of up to 83.09 g/mL. This shows a proof-of-concept for a TeO2-SeO2-HAp coating as a potential non-toxic anti-infective barrier for orthopedic implants with enhanced bio-mechanofunctionalities. [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. [ABSTRACT FROM AUTHOR]

The increasing need for advanced orthopaedic implants necessitates improved materials that offer better biocompatibility and mechanical properties, addressing issues such as implant failure due to poor integration and corrosion. A 3″ diameter, 5-mm-thick pellet of hydroxyapatite (HAP) was prepared and was used as the cathode for the radio frequency (RF) magnetron sputtering system. One hundred nm nanocoating on alumina substrates (HAP/Al2O3) was done using RF magnetron sputtering. The hexagonal (HCP) HAP structure was chosen to deposit on hexagonal α-alumina for better growth and adhesion of the HAP film. The microstructure was analysed using field emission scanning electron microscopy, atomic force microscopy, and glancing angle X-ray diffraction. Elemental analysis was carried out using energy-dispersive X-ray spectroscopy. Mechanical and film adhesion properties were studied using Vicker's hardness and scratch test, respectively. The hardness of the coated sample increases 2.5 times. The optical contact angle increased from 82.88° for pure alumina to 113.53° for HAP/Al2O3 due to the decreased roughness, indicating enhanced hydrophobicity. Pore size, area, and volume were studied using the Brunauer–Emmett–Teller technique. Corrosion resistance in Ringer's solution and dielectric properties were investigated. The antimicrobial investigation was carried out against two different bacteria, namely gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus). Improved adhesion, hardness, corrosion resistance, and biocompatibility properties are correlated with the surface and structural properties. [ABSTRACT FROM AUTHOR]

In this study, intending to control the corrosion of magnesium and its clinical application, a double-layer coating of Hydroxyapatite- Poly lactic-co-glycolic acid was applied on Mg by means of the electrodeposition and the dip method, respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to characterize the phase and morphology of the coatings. The results show a homogeneous coating with a thickness of 20-30 µm. Potentiodynamic polarization of the samples revealed that the double-layer coating exhibited a significant increase in corrosion potential, ranging from -1.82 to -1.4 V, and a decrease in corrosion current, ranging from 2.3 to 0.37 µA/cm2. Moreover, the MTT assay of the samples revealed that the amount of cell proliferation in the vicinity of the 48-hour extract of magnesium samples with double-layer coating had increased, indicating a decrease in the amount of ions released from the surface of magnesium by applying this coating. [ABSTRACT FROM AUTHOR]

A novel ultra-sound assisted method was used to grow zinc-metal organic framework (Zn-MOF) film on magnesium oxide/hydroxyapatite (MgO/HA) composite layer developed using plasma electrolytic oxidation (PEO) on Mg-5Sn-0.2Mn-0.2Ca alloy. The microstructure surface roughness and microhardness tests were performed on the samples to evaluate the mechanical properties of the coatings. The electrochemical corrosion test was performed to evaluate the corrosion resistance of the coated Mg alloy. Further, an in-vitro bioactivity test was performed to study the biocompatibility and bioactivity of the coated alloy, which is an essential aspect of biomedical applications. Results showed that the MgO/HA composite coating was helpful in the in-situ growth of the Zn-MOF particles by mechanically interlocking them. Further, incorporating hydroxyapatite in the coating could also increase the bioactivity. The study also confirmed that the bi-layer coating of Zn-MOF on the MgO/HA composite layer improved the surface roughness, hardness, biocorrosion resistance, and bioactivity making it more likely to be used for orthopedic internal fixation devices. [ABSTRACT FROM AUTHOR]

To improve the corrosion resistance and antibacterial adhesion properties of AZ31 magnesium alloy as an orthopedic implant material, superhydrophobic hydroxyapatite/lauric acid composite coatings (HA/LA) were successfully fabricated on AZ31 magnesium alloy utilizing the hydrothermal method and followed by immersion treatment in lauric acid solution. The underlying HA coating synthesized by hydrothermal technique presents a micro-/nanohierarchical structure, appearing superhydrophilic, while the composite coatings (HA/LA) obtained by subsequent treatment with lauric acid exhibited excellent superhydrophobic properties with a contact angle of 152.5 ± 1.2° and a rolling angle of 1.5 ± 0.3°. Electrochemical measurements and long-term corrosion resistance test conducted in simulated body fluid (SBF) indicate a significant enhancement in the corrosion resistance of the HA/LA composite coating. Meanwhile, in vitro bacterial experiments demonstrated that the superhydrophobic composite coating surface was able to reduce the adhesion of adherent Escherichia coli and Staphylococcus aureus by more than 98%, showing excellent antibacterial adhesion properties, indicating that the superhydrophobic HA/LA composite coating in this work grants magnesium alloy with excellent corrosion resistance and antibacterial properties. [ABSTRACT FROM AUTHOR]

To functionalize the NiTi alloy, multifunctional innovative nanocoatings of Ag-TiO2 and Ag-TiO2 doped with hydroxyapatite were engineered on its surface. The coatings were thoroughly characterized, focusing on surface topography and key functional properties, including adhesion, surface wettability, biocompatibility, antibacterial activity, and corrosion resistance. The electrochemical corrosion kinetics in a simulated body fluid and the mechanisms were analyzed. The coatings exhibited hydrophilic properties and were biocompatible with fibroblast and osteoblast cells while also demonstrating antibacterial activity against E. coli and S. epidermidis. The coatings adhered strongly to the NiTi substrate, with superior adhesion observed in the hydroxyapatite-doped layers. Conversely, the Ag-TiO2 layers showed enhanced corrosion resistance. [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]

Polymer 3D printing has is used in a wide range of applications in the medical field. Polyamide 12 (PA12) is a versatile synthetic polymer that has been used to reconstruct bony defects. Coating its surface with calcium phosphate compounds, such as hydroxyapatite (HA), could enhance its bonding with bone. The aim of this study was to coat 3D-printed polyamide 12 specimens with hydroxyapatite by a simple innovative surface treatment using light-cured resin cement. Polyamide 12 powder was printed by selective laser sintering to produce 80 disc-shaped specimens (15 mm diameter × 1.5 mm thickness). The specimens were divided randomly into two main groups: (1) control group (untreated), where the surface of the specimens was left without any modifications; (2) treated group, where the surface of the specimens was coated with hydroxyapatite by a new method using a light-cured dental cement. The coated specimens were characterised by both Fourier transform infrared spectroscopy (FTIR) and Transmission Electron Microscopy (TEM), (n = 10/test). The control and treated groups were further randomly subdivided into two subgroups according to the immersion in phosphate-buffered saline (PBS). The first subgroup was not immersed in PBS and was left as 3D-printed, while the second subgroup was immersed in PBS for 15 days (n = 10/subgroup). The surfaces of the control and treated specimens were examined using an environmental scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDXA) before and after immersion in PBS. Following the standard American Society for Testing and Materials (ASTM D3359), a cross-cut adhesion test was performed. The results of the FTIR spectroscopy of the coated specimens were confirmed the HA bands. The TEM micrograph revealed agglomerated particles in the coat. The SEM micrographs of the control 3D-printed polyamide 12 specimens illustrated the sintered 3D-printed particles with minimal porosity. Their EDXA revealed the presence of carbon, nitrogen, and oxygen as atomic%: 52.1, 23.8, 24.1 respectively. After immersion in PBS, there were no major changes in the control specimens as detected by SEM and EDXA. The microstructure of the coated specimens showed deposited clusters of calcium and phosphorus on the surface, in addition to carbon, nitrogen, and oxygen, with atomic%: 9.5, 5.9, 7.2, 30.9, and 46.5, respectively. This coat was stable after immersion, as observed by SEM and EDXA. The coat adhesion test demonstrated a stable coat with just a few loose coating flakes (area removed <5%) on the surface of the HA-coated specimens. It could be concluded that the 3D-printed polyamide 12 could be coated with hydroxyapatite using light-cured resin cement. [ABSTRACT FROM AUTHOR]

AbstractIn this manuscript, the application of hydroxyapatite coatings to total ossicular reconstruction prostheses (TORPs) using finite element modeling simulations was investigated to enhance the biocompatibility and mechanical performance of these prosthetic devices for middle ear implants. We focused on evaluating biocompatible materials, particularly polyetheretherketone (PEEK) and titanium, by analyzing their mechanical behavior under simulated conditions. The results revealed that PEEK demonstrates mechanical performance almost on par with titanium, exhibiting excellent stability and resilience within the middle ear environment. PEEK offers several key advantages over titanium, including easier fabrication, greater availability, and a simplified application process for hydroxyapatite coatings. These benefits suggest that PEEK could be a highly effective alternative to titanium for use in middle ear prostheses. The findings of this study highlight the potential of PEEK to improve the design and functionality of middle ear implants, providing a promising direction for future research and development in this field. By leveraging the advantages of PEEK, we can advance the effectiveness and accessibility of middle ear prosthetic devices, ultimately benefiting patients requiring such interventions. [ABSTRACT FROM AUTHOR]

In recent years, many different biomedical implants have been created for prolonged usage within the human body. The number of these implants has been steadily expanding. It is a common practice to use metallic bioimplants as substitutes when attempting to replace human body components in an anatomically acceptable manner. But the metallic bioimplant was mostly made biocompatible by putting a biocompatible coating on its surface and then using the right surface modification techniques. This was the primary method by which the biocompatibility of the bioimplant was achieved. Thermal spraying is a method that is frequently employed in surface modification treatments to modify metallic bioimplants. These methods can be found in the medical field. This is due to the adaptability of the thermal spraying method. Because of their capacity to respond and adapt to physiochemical circumstances, coatings that are based on hydroxyapatite (HAp) are the most popular type to be used in thermal spraying. This is due to the fact that HAp is a naturally occurring mineral. On the other hand, the majority of the HAp coatings are unsuccessful as a result of the coating’s weak mechanical qualities and insufficient adhesive strength. Supplying the coating in question with reinforcement in the form of hard particles and doing so in the appropriate proportions makes it feasible to alter the qualities of HAp-based coatings to fulfill a variety of requirements. This can be accomplished by providing the coating with reinforcement. The purpose of this inquiry was to deconstruct and analyze a variety of thermally sprayed (TS) coatings. These coatings were used to adhere HAp-based coatings on bioimplants. In addition, a detailed discussion is offered on how the reinforcements have an effect on the mechanical and biocompatible qualities of the coatings. In addition, we have discussed the difficulties associated with TS HAp coatings and their potential uses in the manufacturing of 3D biomedical implants through the utilization of cold spray (CS). [ABSTRACT FROM AUTHOR]

In this research, Sr-doped hydroxyapatite, HAp and NiO nanoparticles were used to produce a novel nanocomposite, Sr-doped HAp/NiO. Various analytical and instrumentation techniques such as FTIR, PXRD, UV-DRS, SEM, TEM, and XPS were used to characterize the as synthesized composite material. The nanocomposite acts as an efficient photocatalyst and is able to degrade Congo red (CR) dye up to 95.6% within 40 min under solar light irradiation without any kind of external additive. The HR LC–MS spectrum was recorded to determine the degradation products of the chosen organic dye. Furthermore, the as prepared nanocatalyst also effectively reduced 98.7% of carcinogenic Cr(VI) to Cr(III) within just 10 min. In order to propose the photocatalytic mechanism and to detect the active radicals present, a radical trapping experiment was conducted. As an appealing photocatalyst for wastewater treatment and reduction of toxic chemicals, the research concluded with a methodical and cost-effective process for producing the Sr-doped HAp/NiO nanocomposite. [ABSTRACT FROM AUTHOR]

Titanium alloy Ti6Al4V is widely used in the production of bone implants due to its favorable mechanical properties and biocompatibility. However, implant failures still occur due to lack of osseointegration, tissue infection, and fatigue. Laser shock peening (LSP) is a surface treatment method that can improve the physical, mechanical, and biological properties of Ti6Al4V implants. This method enhances the fatigue life of implants by inducing compressive residual stress on their surface region. In this study, Ti6Al4V samples were subjected to LSP treatment using different laser power densities (9.6 and 14.9 GW / cm 2 ) and with (vinyl tape and commercial black color) and without a protective layer. LSP-treated samples with higher power density exhibited maximum compressive residual stresses. Furthermore, hydrophobicity increased in all samples with increasing laser power density. Notably, the surface roughness results demonstrated significant improvement where the roughness increased with increasing the laser power density. The sample without a protective layer exhibited the highest surface roughness, followed by the black color coated and vinyl tape surface protected samples. The residual stress, surface roughness, and hydrophilicity of the samples were evaluated to determine the optimal LSP parameters. Fatigue tests revealed a remarkable enhancement in the fatigue life of the LSPed samples compared to untreated samples (3 and 2.9 times longer life for black-color coated and without coating samples, respectively). Moreover, the microstructure of laser peening samples and the fracture surface of the fatigue samples were characterized using field emission scanning electron microscopy (FE-SEM). To evaluate the biological characteristics of the optimal LSP-treated samples, a hydroxyapatite coating was applied, and their biological characteristics, including cell viability and adhesion, were investigated. Furthermore, the combination of LSP with hydroxyapatite coating offers a potential solution to promote osseointegration and reduce implant failures. [ABSTRACT FROM AUTHOR]

The hydroxyapatite and copper-doped hydroxyapatite coatings (Ca10−xCux(PO4)6(OH)2; xCu = 0, 0.03; HAp and 3CuHAp) were obtained by the vacuum deposition technique. Then, both coatings were analyzed by the X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and water contact angle techniques. Information regarding the in vitro antibacterial activity and biological evaluation were obtained. The XRD studies confirmed that the obtained thin films consist of a single phase associated with hydroxyapatite (HAp). The obtained 2D and 3D SEM images did not show cracks or other types of surface defects. The FTIR studies' results proved the presence of vibrational bands characteristic of the hydroxyapatite structure in the studied coating. Moreover, information regarding the HAp and 3CuHAp surface wettability was obtained by water contact angle measurements. The biocompatibility of the HAp and 3CuHAp coatings was evaluated using the HeLa and MG63 cell lines. The cytotoxicity evaluation of the coatings was performed by assessing the cell viability through the MTT assay after incubation with the HAp and 3CuHAp coatings for 24, 48, and 72 h. The results proved that the 3CuHAp coatings exhibited good biocompatible activity for all the tested intervals. The ability of Pseudomonas aeruginosa 27853 ATCC (P. aeruginosa) cells to adhere to and develop on the surface of the HAp and 3CuHAp coatings was investigated using AFM studies. The AFM studies revealed that the 3CuHAp coatings inhibited the formation of P. aeruginosa biofilms. The AFM data indicated that P. aeruginosa's attachment and development on the 3CuHAp coatings were significantly inhibited within the first 24 h. Both the 2D and 3D topographies showed a rapid decrease in attached bacterial cells over time, with a significant reduction observed after 72 h of exposure. Our studies suggest that 3CuHAp coatings could be suitable candidates for biomedical uses such as the development of new antimicrobial agents. [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]

The present work aimed to produce HAp nanoparticles doped with Zn and Ni in order to analyze the incorporation of these elements in the catalytic and antimicrobial properties of HAp. The samples were obtained by the microwave-assisted hydrothermal method in 30 min at 150 °C. XRD and FTIR results showed that HAp was formed without the presence of secondary phases, and Rietveld refinement indicated a reduction in crystallite size after doping. Nanorod-like morphologies were observed by SEM-FEG with reduction in particle size and increase in specific surface area. Furthermore, the hidden gap at 3.26 eV, photoluminescence indicated that there was a predominance of deep defects and XPS showed the presence of dopants on the HAp surface. The catalytic results in the degradation of methylene blue dye indicated that the zinc-doped sample removed 97.85 % under sunlight, 66.81 % under UV light and 70.64 % under ultrasound. After four cycles of reuse under sunlight, good photocatalytic performance was maintained, and inhibition tests indicated that holes and hydroxyls are the active radicals. Antimicrobial activity tests showed that zinc-doped and co-doped samples were efficient in inhibiting Gram-negative bacteria (Escherichia coli). This work brings a promising alternative application for hydroxyapatite in environmental and microbial remediation. [ABSTRACT FROM AUTHOR]

NiTi alloys are actively used in medicine as implants because of their mechanical properties. At the same time, however, the NiTi surface is not biologically active, which has a negative effect on osteogenesis. In addition, Ni is capable of causing various toxic reactions in the human body. It is therefore necessary to create a composite coating that is both bioactive and prevents the release of Ni ions. It has been shown that by changing the modes of plasma assisted RF sputtering of a calcium phosphate target, it is possible to obtain coatings with different contents of the amorphous phase. The coatings formed consist of hydroxyapatite and amorphous calcium phosphate. On the surface of a sample not treated with argon plasma, there are no phases containing calcium or phosphorus, although these elements are present on the surface. The different ways in which the CaP coatings were applied also affected their structure. It was found that the CaP coatings of samples M2 and M3 have mediocre corrosion resistance, dissolving quickly. This has a positive effect on the ability to osteogenesis, which was discovered as a result of in vitro tests. These tests have shown that the sample obtained at I discharge = 30 A and U bias = 30 V has the highest bioactivity and produces the lowest percentage of dead cells. [ABSTRACT FROM AUTHOR]

Calcium strontium phosphate was electro-crystallized on Ti along with hydroxyapatite (HA). Stock solutions of 167 mM CaCl2, 167 mM SrCl2, and 100 mM NH4H2PO4 were initially prepared. Two different electrolyte formulations of equi-amounts of (CaCl2 + SrCl2) and NH4H2PO4 were used. The Ca:Sr ratios were maintained as 9:1 and 3:1, respectively, in these two formulations. Using these solutions, a cathodic deposit was obtained on Ti using ultrasonic agitation of the electrolyte at the current density of 10 mA/cm2 for 60 min. The electrolytes were heated at 50°C. X-ray diffraction (XRD) and field-emission scanning electron microscope (FE-SEM) analysis were utilized to characterize the phase compositions and surface morphology of the coatings. A surface roughness tester, an universal testing machine, and contact angle measurements were used to estimate the coating roughness, pull-off tensile adhesion strength, and wettability, respectively. The coatings were composed of hydroxyapatite (HA) and calcium strontium phosphate. The strontium (Sr) substitution was nearly 0.5% and 1% in the coatings obtained from the 9:1 and 3:1 Ca:Sr ratios, respectively. The coatings contained predominantly spherical crystals and occasional plate-like crystals attached to the substrate. Both the coatings displayed a similar surface roughness of about 450 nm. The coating obtained from the first electrolyte (Ca:Sr = 9:1) had a higher contact angle in simulated body fluid, but a lower pull-off adhesion strength than the coating obtained from the second (Ca:Sr = 3:1) electrolyte. [ABSTRACT FROM AUTHOR]

Aims: This study aims to achieve an electrochemical deposition of Sr- and Zn-doped hydroxyapatite coating on stainless steel mini-implants and verify it by Fourier transform infrared spectroscopy (FTIR). Materials and methods: Synthesis of the powder: Zinc-Sr hydroxyapatite nanoparticles were synthesised in this work using a sonochemical-mediated hydrothermal technique. Electrochemical deposition of the coating: The coating was applied electrochemically onto commercially available stainless steel miniplates measuring 2 mm in thickness and screws measuring 2 x 8 mm. The coated implants were analysed for their functional groups using Fourier transform infrared spectroscopy (FTIR) covering a frequency range of 4000-400 cm-1. Results: The chemical nature and functional groups involved in the successful production of Zn-Sr/HAP were predominantly elucidated by FT-IR spectroscopy investigations. In FTIR, the coated stainless-steel plates showed 3 peaks at 1024.85, 601.02, and 561.26. The coated stainless-steel screws showed 2 peaks at 1028.43 and 563.23. Conclusion: Zinc and strontiumdoped hydroxyapatite coating can be done on stainless steel miniplates using electrochemical deposition. [ABSTRACT FROM AUTHOR]

Controlling blood loss is crucial for saving lives during trauma. Based on the current application of solid waste in hemostatic materials, this study reports the synthesis of a hydroxyapatite/tourmaline composite material (referred to as ST) and a hemostatic sponge (referred to as STS). These materials were synthesized through hydrothermal processes and lyophilization techniques using seashells, tourmaline, and chitosan as precursors. The phase analysis and microstructure characterization were performed using XRD, SEM, TEM, and HRTEM. Owing to the spontaneous polarization of tourmaline attracting free ions in the system, the shells were deposited on the surface of tourmaline particles in the form of hydroxyapatite (HA) through dissolution and recrystallization during the hydrothermal process. HA can release free Ca2+, an important component in the coagulation system, while tourmaline can enhance cell metabolism by reducing water molecular clusters, thereby altering the permeability of cell membranes. ST particles were incorporated into the chitosan sponge matrix to prevent particle shedding. Through orthogonal design experiments on the preparation process of ST, the optimal preparation conditions were determined as follows: a hydrothermal temperature of 180 °C, a hydrothermal time of 12 h, a pH value of 8, and a shell-to-tourmaline ratio of 8 : 1. The composite materials were evaluated for their adsorption capacity, clotting time, hemolysis rate, antibacterial rate, and cytotoxicity. The results demonstrated a higher liquid adsorption rate, significantly reduced clotting time, a hemolysis rate of <5.0%, an antibacterial capacity of 88.5%, and lower cytotoxicity. These findings suggest that STS has the potential to be a safe, effective, and cost-efficient hemostatic agent. [ABSTRACT FROM AUTHOR]

In this study, hydroxyl apatite (HA) as a bio-ceramic is coated on the TiNi shape memory. In this approach, Tri-ethanolamine and butanol were used as suspensions. To set up Electrophoretic Deposition (EPD) process, voltages of 20, 30 and 40 volts were applied on the cathode for 1-5 minutes. The sintering process was done in the Ar atmosphere for two hours at 800°C. SEM and XRD were used to investigate surface morphologies and phases. Obtained results showed that higher electrical currents led to generation of thicker coatings registering 105% and 12.3% improvement for weight and thickness after 6 minutes, respectively. Moreover, Transformation of HA to other calcium phosphate phases doesn’t happen at a sintering temperature of 800°C. Moreover, a uniform, homogeneous and crackles coating can be reached in the voltage of 30 volts at low sintering temperatures. This process can be utilized an alternative technique for bioactive coatings. [ABSTRACT FROM AUTHOR]