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Background: Mesenchymal stem cells (MSCs) are multipotent stromal cells and could exert hepatoprotective effects against acute liver injury, steatohepatitis, and fibrogenesis. Here, we evaluated the effects of human adipose derived stem cells (hADSCs) to attenuate experimentally induced hepatic fibrosis and early cirrhosis in rats. Methods: Hepatic fibrosis was induced by intraperitoneal injections of CCl4 (0.1 ml/100 g body weight) twice a week for 8 weeks. hADSCs were isolated and cultured on polyethylene discs coated with hydroxyapatite and 2 cm diameter disc was surgically implanted on the right lateral lobe of the liver. Discs implanted without hADSCs served as control. The animals were injected again with CCl4 once a week for another 8 weeks. All the animals were sacrificed at the end of 16th week. Results: Serial administrations of CCl4 resulted in well developed fibrosis and early cirrhosis at 8th week which maintained until the 16th week. Animals treated with hADSC discs depicted over 50% decrease of collagen with significant increase in serum albumin and total protein levels. Immunohistochemical staining for TGF-β1, α-smooth muscle actin, and collagen type I and type III demonstrated marked decrease compared to the animals without hADSC treatment. Conclusions: Treatment with hADSCs improved liver functions, markedly reduced hepatic fibrosis and early cirrhosis. Various pleiotropic and paracrine factors secreted from the hADSCs seem to serve as reparative functions in the attenuation of liver cirrhosis. The data demonstrated that treatment with hADSCs can be successfully used as a potent therapeutic method to prevent progression of hepatic fibrosis and related adverse events. [ABSTRACT FROM AUTHOR]

The surface physico-chemistry of metallic implants governs their successful long-term functionality for orthopedic and dentistry applications. Here, we investigated the feasibility of harmoniously combining two of the star materials currently employed in bone treatment/restoration, namely, calcium-phosphate-based bioceramics (in the form of coatings that have the capacity to enhance osseointegration) and titanium alloys (used as bulk implant materials due to their mechanical performance and lack of systemic toxicity). For the first time, bovine-bone-derived hydroxyapatite (BHA) was layered on top of Ti6Al4V substrates using powder injection laser cladding technology, and then subjected, in this first stage of the research, to an array of physical-chemical analyses. The laser processing set-up involved the conjoined modulation of the BHA-to-Ti ratio (100 wt.% and 50 wt.%) and beam power range (500–1000 W). As such, on each metallic substrate, several overlapped strips were produced and the external surface of the cladded coatings was further investigated. The morphological and compositional (SEM/EDS) evaluations exposed fully covered metallic surfaces with ceramic-based materials, without any fragmentation and with a strong metallurgical bond. The structural (XRD, micro-Raman) analyses showed the formation of calcium titanate as the main phase up to maximum 800 W, accompanied by partial BHA decomposition and the consequential advent of tetracalcium phosphate (markedly above 600 W), independent of the BHA ratio. In addition, the hydrophilic behavior of the coatings was outlined, being linked to the varied surface textures and phase dynamism that emerged due to laser power increment for both of the employed BHA ratios. Hence, this research delineates a series of optimal laser cladding technological parameters for the adequate deposition of bioceramic layers with customized functionality. [ABSTRACT FROM AUTHOR]

The coating of hydroxyapatite (HAP) on the surface of bio-inert metallic implants to augment their bioactivity is in use for the last two decades. Substitution of various materials in HAP further improves the functionality of these coatings. We demonstrate coating of Ti6Al4V alloy sheets with strontium and niobium reinforced HAP using microwave (MW) irradiation technique. Physical characterization revealed, uniform semicrystalline hydroxyapatite coating with enhanced surface roughness and microhardness. The increased surface roughness was accompanied by higher wettability and more protein adsorption. Electrochemical corrosion assessment showed a dramatic increase in corrosion potential and a noticeable decline in corrosion current density suggesting an enhanced anticorrosive behaviour. These implants also exhibited improved hemocompatibility and bacteriostatic properties. Cell viability and confocal microscopy studies of the coated samples showed enhanced cell attachment on the surface. We propose microwave irradiation as a fast and hassle-free alternative for one-pot synthesis and deposition of ionic substituted HAP on metallic implants. [ABSTRACT FROM AUTHOR]

The presence of F− ions in water is either a helpful or harmful outcome, contingent upon the concentration level of the pollutant. In this work, hydroxyapatite/chitosan (HAp/CS) nanocomposites were prepared incorporating varying weight percentages of chitosan with HAp, using co-precipitation followed by lyophilization without employing any cross-linking agents for the adsorption of F− ions. An increase in the concentration of chitosan in the HAp matrix significantly enhanced the colloidal stability, F− ion adsorption capacity, and reduced the particle size (length 38% and width 86%) when compared to HAp. The respective maximum F− adsorption capacity of HAp/CS1, HAp/CS2, HAp/CS3, and HAp/CS4 nanocomposites were 56 mg/g, 80 mg/g, 82 mg/g, and 100 mg/g at pH 7, which was considerably higher (10 times) than HAp when compared to other existing reports. The adsorption isotherm and kinetics of HAp and HAp/CS nanocomposite adsorbent confirmed the monolayer and strong chemisorption mechanisms. The surface morphology of the adsorbent after adsorption of F− ions changed from rod to sphere along with an increase in particle size, as confirmed by HR-TEM. Moreover, FTIR and XPS analysis revealed the surface interaction between the adsorbent and F− ions through ion exchange and electrostatic interaction, which lead to the formation of fluorapatite. HAp/CS4 showed 2.5 times higher sustainable regeneration efficiency (90% in 30 min) up to 7th cycle than HAp. Furthermore, the solution pH (5–7) of treated water was maintained at neutral pH after fluoride adsorption, rendering the water potable. Hence, these results demonstrate that chitosan plays a significant role in the removal of F− ions and this composite is ideal for F− ion adsorption applications. [ABSTRACT FROM AUTHOR]

Active alginate-based coatings with quercetin glycoside and complexes of hydroxyapatite/quercetin-glycoside were used to study the shelf life of fresh cut papaya stored at 6 °C. Hydroxyapatite was used as a carrier for the release of the bioactive compound. The parameters considered affecting the quality of the fruit during storage were weight loss, color, texture, sugars and volatile compounds. Active coatings with hydroxyapatite and quercetin glycoside proved a higher capacity to slow down the degradation phenomena studied, showing less weight loss, a lower reduction in glucose and fructose, as well as better firmness, than the other samples after 14 days of cold storage. Benzyl isothiocyanate, the characteristic odor compound of papaya fruit, ranged from approximately 10.0 μg/kg in fresh cut fruit to approximately 7.50 μg/kg in samples coated by alginate with hydroxyapatite/quercetin and 3.6 μg/kg in the fresh cut papaya without coating after 14 days of cold storage. The trials also indicated greater effectiveness of alginate coatings alone and with quercetin-glucoside in preserving the color of freshly cut papaya. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) and its alloys are promising materials for temporary biomedical implants such as bone fracture fixation devices. Unfortunately, rapid degradation in the physiological environment and cytotoxicity have impeded their clinical use. Hydroxyapatite (HA) coatings synthesized via ethylenediaminetetraacetic acid calcium disodium salt hydrate (EDTA-Ca) and potassium dihydrogen phosphate (KH2PO4) have emerged as one effective strategy to enhance the corrosion resistance and biocompatibility of Mg and its alloys. However, effects of the concentrations of EDTA-Ca and KH2PO4 on the morphology, corrosion protection, and biocompatibility of HA coatings remain unclear. In this study, the morphology, thickness, corrosion protection, and cytocompatibility of the HA coatings fabricated on high-purity Mg with different concentrations of the synthetic solution are investigated. Our results show that the fabricated coatings are composed of a dome-shaped outer HA layer and an inner Mg(OH)2 layer. With decreasing the concentrations of the synthetic solution, the HA and Mg(OH)2 layers become thinner and thicker, respectively, and the corrosion resistance and cytocompatibility of the coated Mg become better. The formation mechanism of the prepared coatings and relationships between the concentrations of the synthetic solution and the corrosion and biological characteristics are also discussed. [ABSTRACT FROM AUTHOR]

Membranes of guided bone regeneration (GBR) are widely used in oral implant surgeries. This study successfully developed a new GBR membrane, hydroxyapatite (HA) coating, on Mg–2Zn–Mn–Ca–Ce alloy substrates via a hydrothermal technique. The features of the HA coatings were investigated by complementary characterization methods (SEM, XRD, EDS, and static contact angle). The in-vitro degradation behavior and biocompatibility of HA-coated and bare Mg–2Zn–Mn–Ca–Ce alloys were analyzed in detail. The HA coatings exhibited porous outer surface and compact inner layer, outstanding hydrophilicity, and thus significantly improved the anticorrosion/biodegradability of the Mg alloy substrate in Hank's solution. Moreover, the results of CCK-8 assays and cell adhesion tests suggested that HA-coated samples could further promote cell adhesion and proliferation. HA-coated Mg–2Zn–Mn–Ca–Ce alloys have good biodegradation behavior and biocompatibility, indicating great potential as a GBR membrane material.

This study aims to evaluate the corrosion behavior of WE43 alloy with plasma electrolytic oxidation (PEO)/hydroxyapatite (HA)-polydopamine (PDA) duplex coating. HA-PDA is co-deposited as the top layer using an electrodeposition process by varied dopamine hydrochloride concentration and deposition time following the PEO process. The findings show the development of a corrosion-resistant coating by regulating the surface morphology. Furthermore, long-term electrochemical impedance spectroscopy reveals that the total impedance of the optimized PEO/HA-PDA coating (deposition time = 10 min and dopamine hydrochloride concentration = 1 mg/mL) increased from 1720 Ω on day 1 to 14,600 Ω following 21 days of immersion. Co-deposited HA-PDA shows less hydrogen release and higher adhesion strength than PEO/HA samples. Finally, the PEO/HA-PDA coating is desirable for magnesium bone implants by considering the bioactivity of the coating resulting in improved cell-surface interaction. [Display omitted] • A duplex PEO/HA-PDA coating was developed on WE43 for bone implants. • Duplex coating morphology was controlled by dopamine content and coating time. • Hydrogen release decreased in PEO/HA-PDA compared to PEO during 7 days • Long-term corrosion resistance of duplex coatings was studied in body fluids. • PEO/HA-PDA promoted MG63 cell proliferation over PEO/HA. [ABSTRACT FROM AUTHOR]

Titanium has proven to be a game-changing biomaterial in biomedical engineering. Titanium and its alloys offer superior properties such as machinability, mechanical strength, biocompatibility, and corrosion resistance, making them indispensable for safer and more efficient biomedical treatments. While commercially pure titanium (Cp-Ti) is an exceptional material for medical applications, it has some limitations. Allergic reactions can manifest as localized inflammation around the implant, and corrosion compromises implant stability. Corrosion starts with cracking from the surface and disrupts the protective passive oxide layer when touching body fluids, and failure occurs. This study utilized a combination of techniques including grain refinement of Cp-Ti via equal channel angular pressing (ECAP), two-step anodization (for creating titanium oxide nanotubes coatings), annealing at 450°C and 570°C, and immersion in simulated body fluid (SBF) to create a Hydroxyapatite (HA) film coating. These methods addressed various challenges and provided a positive approach to improving corrosion behavior. The microstructure of Nano-Ti was evaluated by Transmission Electron Microscopy (TEM). The morphology of the as-anodized samples and corroded areas were investigated using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The crystalline phases of titanium nanotubes (TNTs) were evaluated through X-ray diffraction (XRD). The presence of hydroxyapatite particles was analyzed and characterized by FESEM coupled with Energy Dispersive Spectroscopy (EDS) and Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR). The corrosion behavior was evaluated using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). Results indicated that grain refinement and successive surface modifications significantly impact corrosion performance. The nanostructured (Nano-Ti) sample, after the final modification stage, exhibited an approximately 11-fold decrease in corrosion rate and over a 450-fold rise in polarization resistance (7.4 MΩ) compared to as-anodized Cp-Ti sample and a 7-fold increase in its Cp-Ti counterpart, and showed excellent adhesion strength compared to other samples. [Display omitted] • The Nano-Ti samples reduce localized corrosion and prevent pit corrosion. • Surface modification in Nano-Ti increases the Rp and decreases the CR. • A defect-free HA-layer in Nano-Ti increases considerably overall resistance. • Hydroxyapatite coating increases total resistance in low frequencies. • The adhesion strength of the metal/TNT interface in Nano-Ti is significantly more than Cp-Ti. [ABSTRACT FROM AUTHOR]

The coatings of co-substituted bioactives play an important role in stimulating biological and physical properties for biomedical applications. Hydroxyapatite (HAP), a mineral compound possessing a hexagonal structure, exhibits high thermodynamic stability under typical physiological conditions. In this experimental study, Si4+-doped HAP coatings with varying concentrations (2.5 %, 5 %, and 10 % wt) were prepared on a Ti-6Al-4V substrate using the spin-coating technique and extreme centrifugal force (2500 rpm). The coated samples were characterized by XRD, FTIR, AFM, FESEM, and EDS techniques. The presence of cracks and voids in the HAP coatings detrimentally affected the performance of the implants. Tetraethyl orthosilicate (TEOS) was used in the coatings to mitigate the cracks and voids. Polarization and EIS studies in the simulated body fluid (SBF) were used to assess the corrosion resistance of the coatings. The decrease in current density and the improved resistance to corrosion observed in the coated samples, as compared to the uncoated Ti-6Al-4V, demonstrate the corrosion-inhibiting effects of anodizing. The integration of Si4+ ions in the structure of HAP caused the size of nanoparticles to decrease from 16.23 nm to 11.67 nm, and the surface roughness of the produced coatings exhibited a decrease from 29.18 to 5.65 nm. In the Nyquist plots, the 5 % Si4+-doped HAP coating displayed the highest R ct value of 17.99 MΩ.cm2 compared to the bare Ti-6Al-4V with a resistance of 0.13 MΩ.cm2. The 5 % Si4+-doped HAP coating was chosen as the optimal sample based on the study results. The results of this work show that surface modification with Si4+-doped HAP coatings is a promising approach for improving the functionality of the Ti-6Al-4 V alloy for biomedical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Aseptic loosening and inadequate osseointegration are significant issues associated with titanium alloy implants in complex body fluid environments. Surface coatings techniques are often employed to enhance the bioactivity and osseointegration capabilities. In this research, biocomposite coatings were fabricated on Ti-6Al-4V alloy employing micro-arc oxidation (MAO) and the integration of micro-arc oxidation/electrophoretic deposition (MAO/EPD) technology. Microstructure, bioactivity, and corrosion resistance of the coatings were studied. To investigate the effect of the coatings on the stress corrosion cracking (SCC) behavior of Ti-6Al-4V alloy, slow strain rate tension (SSRT) tests were conducted in simulated body fluid (SBF). Results show that the adhesive strength of the MAO/EPD composite coatings is around 28.41N, with an average contact angle of 19.05 °, indicating excellent wettability and biocompatibility. The corrosion rate of biocomposite coatings is 3.43 μm·a−1 and the biocomposite coatings exhibit excellent SCC resistance, with a SCC sensitivity of 9.21%, which is significantly lower than the 18.39% of Ti-6Al-4V alloy. This can be attributed to the lower porosity of the coatings, which can provide excellent protection for the alloy. [ABSTRACT FROM AUTHOR]

Ti-6Al-4V-ELI titanium alloy is useful in biomedical applications due to its mechanical characteristics. To improve properties, alloy surfaces was coated with various methods. In this work, titanium–hydroxyapatite(Ti-HA) composite coatings were deposited on Ti-6Al-4V-ELI through mechanical milling(MM). Coatings’ phase analysis, surface morphology, wear, corrosion, and in vitro performance were examined. The results show that average coating thickness varied between 190 and 305 µm. The substrate has a specific wear rate of 7.22×10−4 mm3/Nm, while Ti5HA has the lowest rate among composite coatings at 2.7×10−4 mm3/Nm. Coated surfaces demonstrated better corrosion resistance than bare substrate in electrochemical tests conducted in Ringer's and phosphate buffered saline (PBS) physiological solutions. Ti5HA has the lowest Icorr (0.119 μA/cm2) in Ringer's solution, while Ti10HA has the lowest Icorr (0.245 μA/cm2) in PBS solution. Apatite layer development was seen on all coated surfaces following 7 and 14 days of in vitro experiments. [ABSTRACT FROM AUTHOR]

• We proposed post-SC-CO 2 electrodeposition approach of the preparation of Ni/HAP coating. • The post-SC-CO 2 process demonstrates a novel function surpassing both SC-CO 2 and conventional electrodeposition methods. • Post-SC-CO 2 method prepared Ni/HAP coating exhibits 70.86% higher corrosion resistance than conventional methods. The corrosion resistance of brass materials, commonly used in PCBs, MEMS, and the automobile industry, is significantly compromised in chlorine-containing environments prevalent in marine, chemical, and petroleum industries. To address this issue, we proposed the development of a nickel/hydroxyapatite (Ni/HAP) composite coating using a post-supercritical carbon dioxide (post-SC-CO 2) approach, aiming to enhance corrosion resistance compared to conventional methods. The study evaluates the effectiveness of the post-SC-CO 2 process against SC-CO 2 and conventional electrodeposition techniques. The fabricated Ni/HAP coatings are examined through various physico-chemical characterizations to elucidate their surface morphology, phase purity, and chemical compositions. The surface morphology of Ni/HAP coating from post-SC-CO 2 method features micro-cones, indicating SC-CO 2 phenomena at atmospheric pressure. The electrochemical impedance spectroscopy analysis demonstrates that the conventionally electrodeposited Ni/HAP coating attains a corrosion resistance of 4.331 × 104 Ω cm2, 31.59 % enhancement in protection efficiency compared to a standalone Ni coating. In contrast, coatings fabricated using SC-CO 2 and post-SC-CO 2 methods exhibit corrosion protection efficiencies that are 92.97 % and 70.84 % higher, respectively, compared to the conventional electrodeposition technique. These findings highlight the superior performance of the post-SC-CO 2 electrodeposition method in improving corrosion resistance, indicating its significant potential for industrial applications. [ABSTRACT FROM AUTHOR]

To reduce infections caused by orthopedic implant surgeries, coatings consisting of cefazolin, hydroxyapatite (HA), and chitosan with sustained drug release were deposited on a Ti6Al4V surface by electrophoretic deposition. The effects of incorporating micro- and nano-HA into the coatings on drug adsorption, release, and antimicrobial activity were investigated. The results indicated that the addition of HA particles greatly increased drug adsorption and that the nano-HA particles adsorbed more drug than the micro-HA particles. Furthermore, cefazolin/chitosan coatings had higher drug release rates in the initial stage. After 45 days, approximately 80.2 ± 2.0, 75.4 ± 1.9, and 67.9 ± 2.6 % drug released from cefazolin/chitosan, cefazolin/micro-HA/chitosan, and cefazolin/nano-HA/chitosan coatings, respectively. The release rate of the cefazolin/HA/chitosan coatings increased significantly after 3 days. Nano-HA provided a steadily increasing release, whereas micro-HA resulted in a burst release from the coating. All three coatings showed >90 % antibacterial activity and >10 mm inhibition zone against Staphylococcus aureus. [Display omitted] • Laser-treated Ti6Al4V provided good coating adhesion. • Micro-HA resulted in a burst release from the coating. • Nano-HA provided the coating a steadily increasing release. • Drug-containing coatings had good antibacterial activity against S. aureus. [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]

Biodegradable materials, especially Magnesium (Mg) and its alloys, are preferred for bone implants due to their compatibility with host tissue and biomechanical support. However, their rapid corrosion and vulnerability to structural failure, compounded by infections from antibiotic-resistant bacteria, pose significant challenges. Addressing these issues, we developed silicate-based composite coatings with varying CuO concentrations (1, 5, and 7 wt%) on Mg using plasma electrolytic oxidation (PEO). This study evaluated the coatings' surface characteristics, degradation behavior, and optimum composition. Our analyses, including XPS and EDX, confirmed the presence and influence of CuO on the coatings. We observed enhanced hydroxyapatite crystallization in CuO-doped coatings, which is critical for implant biocompatibility. These coatings also showed improved corrosion resistance and controlled ion release, likely due to silicate composition and CuO's sealing effects. Antimicrobial assays revealed that CuO concentration influenced bacterial and fungal adhesion, varying with microorganism type. Our findings demonstrate that incorporating inert copper particles into PEO coatings alters their chemical and elemental properties, enhancing bioactivity, corrosion resistance, and antimicrobial efficacy. These multifaceted improvements position our CuO-doped silicate coatings as a pioneering solution in bone implant technology, potentially setting new standards for safety, efficacy, and longevity in orthopedic and dental implants. [Display omitted] [ABSTRACT FROM AUTHOR]

• Laser treatment can modulate the morphology, thickness and density of HA coating. • Microstructures and thin oxide layers promote nucleation and deposition of HA. • Adhesion strength of HA coating to Mg alloy substrate is 31.86 ± 1.71 MPa. • Coating effectively reduces the corrosion rate of magnesium alloys to 0.146 mm/y. • Coating with good biological activity can promotes osteoblasts proliferation. Magnesium and its alloys have attracted attention as medical bone implant materials due to their excellent biocompatibility, bone-like mechanical properties, and degradability. However, the clinical application of magnesium is limited by the fact that it corrodes too quickly in body fluids, leading to premature mechanical failure. Surface hydroxyapatite coatings can significantly reduce the initial corrosion of magnesium alloys, but suffer from the problems of non-dense coatings, many defects and poor adhesion strength to the substrate. In this study, we propose femtosecond laser construction of microemulsion cone structures on the surface of magnesium alloys to significantly enhance the densities and thicknesses of the coatings, as well as to improve the bonding strength of the coatings to the substrate, which ultimately reduces the corrosion rate. The corrosion rate of modified hydroxyapatite coating in simulated body fluid is only 0.146 mm/y, and it has the ability to rapidly induce hydroxyapatite mineralization and promote osteoblast proliferation. Furthermore, the surface morphology, chemical composition, and wettability of the laser-modified Mg alloy were analyzed. It was demonstrated that the microstructure and thin oxide layer formed on the surface of the magnesium alloy could provide more sites for HA nucleation, which promotes the deposition and growth of HA and the existence of a mechanical interlocking effect with the substrate. The application of femtosecond laser surface modification represents a rapid and efficacious approach to enhance the quality of hydroxyapatite coatings. This method has successfully controlled the corrosion rate of magnesium alloys with excellent biocompatibility, thereby overcoming potential obstacles to the use of magnesium alloys in clinical applications. [ABSTRACT FROM AUTHOR]

The integration of poly (lactic acid) (PLA) in 3D printing has revolutionized the biomaterial engineering. This synergy between PLA and 3D printing holds immense potential for advancing tissue engineering and human health. The purpose of this study is to evaluate nucleated hydroxyapatite (HA) on polydopamine (PDA)-coated 3D printed PLA scaffolds, focusing on chemical composition, morphology, crystallinity, wettability, porosity, and biocompatibility via MTT assay. 3D printed PLA scaffolds were designed using computer-aided software (CAD). These scaffolds were immersed in a dopamine salt solution for 24 h to create a thin PDA layer and then placed in Simulated Body Fluid (SBF) for 5 days to stimulate apatite layer formation, observed through FE-SEM. PLA scaffolds had smooth surfaces, while PLA–PDA surfaces were different, and PLA–PDA–HA scaffolds revealed more homogeneous distribution of HA. PLA scaffolds had higher porosity (88%) and hydrophobic, whereas PLA–PDA scaffolds became hydrophilic due to the introduced amine and hydroxyl groups from the PDA coating. PLA–PDA scaffolds were amorphous, indicating reduced crystallinity, while PLA–PDA–HA displayed crystalline structure. The PLA–PDA–HA scaffolds declined most in weight loss (0.7%) due to the hydrolytic degradation of HA. In contrast the PLA–PDA scaffolds were the least degraded, with steady degradation trend lasting up to the 21st day of immersion. The PLA–PDA–HA scaffolds, with HA nucleation, exhibited the highest cell viability (145%) on day 7, emphasizing the crucial role of robust cell viability in tissue engineering. In conclusion, the PLA–PDA–HA scaffold was the most robust option due to its enhanced adhesion, biocompatibility, and potential protection against degradation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydroxyapatite (HA) coating was fabricated by flame spray technique (FS). • Synthesized nanohydroxyapatite powder was used directly without any granulation. • Hydroxyapatite and tricalcium phosphate (TCP) were present in the coatings. • Nano-sized hydroxyapatite formed after simulated body fluid (SBF) test for 7 days. • Porous structure enhanced bioactivity as resorption and nucleation rate increased. This research involves fabrication and characterization of flame sprayed hydroxyapatite (HA) coatings on 316 stainless steel substrates where the desirable structure with high porosity can be obtained. Nano-sized HA powder was synthesized and calcined at 600 °C. The subsequent powder was used as feedstock powder for flame spray technique (FS). In-flight particles of HA were spherical with the range of particle size between 3–37 µm. The average coating thickness was 128 µm and the crystalline phases were a mixture of HA and tricalcium phosphate (TCP). Simulated body fluid (SBF) test showed that HA layer was formed after 7 days. Highly bioactive properties were due to high surface area from rough coating and porous structure, which would be beneficial from the flame spray technique. The coating is promising for applications in biomedical field. [ABSTRACT FROM AUTHOR]

• Hydroxyapatite (HAP) composite paper with biocompatibility and hygroscopicity was prepared. • HAP composite paper has better hygroscopic and triboelectric properties than pure paper, making it more suitable for wearable sensing applications. • The HAP composite paper-based triboelectric nanogenerator can detect and distinguish different joint movements. • Hemostatic and disposable HAP composite paper can be degraded in the natural environment without harm. Wearable triboelectric nanogenerators (TENGs) have attracted considerable attention in the field of self-powered sensors that can be worn on the skin directly without packaging because of their breathability, conformability, and sensitivity to collect biomechanical energy. However, high humidity on the skin can affect the wearable TENG output performance, substantially affecting the sensor performance and stability. When worn for a long time, humidity can even cause skin inflammation. Thus, for a wearable TENG, moisture control and biocompatibility are also key factors that need to be addressed. Herein, we report a hygroscopic and biocompatible paper-based TENG using a hydroxyapatite (HAP) mineral coating to enhance the paper fiber. The mineral coating can maintain the surface of the paper fiber, which will not cause large external deformation of the paper fiber under a force, avoid squeezing out excess water, and keep the friction surface dry, avoiding humidity affecting the output performance. Without interfering with the performance of the TENG, the maximum water absorption of the HAP composite paper is ∼8 μL. The HAP composite paper–based TENG (4 cm2) has an open-circuit voltage and short-circuit current 5.8 times and 4.2 times that of pure paper, respectively, and can obtain 80.4 mW/m2 output and directly light 117 LEDs. At relative humidity values of 25.7 %, 43.1 %, and 58.8 %, the performance retained the peak values of 80.2 %, 68 %, and 63.7 %, respectively. Even at a high relative humidity of 71.7 %, the triboelectric performance of HAP composite paper is retained 59.3 %, and the stability under humidity is better than that of pure paper (45.6 %). In addition, the mineral paper can even work with tissue fluid and output performance decreases by 43.8 %. The mineral-enhanced paper TENG with high power generation performance, hygroscopicity, biocompatibility, and degradability provides a new perspective for disposable wearable sensors, even in medical treatment. [ABSTRACT FROM AUTHOR]

To evaluate the adhesion of mono and duospecies biofilm on a commercially available dental implant surface coated with hydroxyapatite nanoparticles (nanoHA). Titanium discs were divided into two groups: double acid-etched (AE) and AE coated with nanoHA (NanoHA). Surface characteristics evaluated were morphology, topography, and wettability. Mono and duospecies biofilms of Streptococcus sanguinis (S. sanguinis) and Candida albicans (C. albicans) were formed. Discs were exposed to fetal bovine serum (FBS) to form the pellicle. Biofilm was growth in RPMI1640 medium with 10% FBS and 10% BHI medium for 6 h. Microbial viability was evaluated using colony-forming unit and metabolic activity by a colorimetric assay of the tetrazolium salt XTT. Biofilm architecture and organization were evaluated by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). AE surface had more pores, while NanoHA had even nanoHA crystals distribution. Roughness was similar (AE: 0.59 ± 0.07 µm, NanoHA: 0.69 ± 0.18 µm), but wettability was different (AE: Θw= 81.79 ± 8.55°, NanoHA: Θw= 53.26 ± 11.86°; P = 0.01). NanoHA had lower S. sanguinis viability in monospecies biofilm (P = 0.007). Metabolic activity was similar among all biofilms. In SEM both surfaces on C. albicans biofilm show a similar distribution of hyphae in mono and duospecies biofilms. AE surface has more S. sanguinis than the NanoHA surface in the duospecies biofilm. CLSM showed a large proportion of live cells in all groups. The nanoHA surface reduced the adhesion of S. sanguinis biofilm but did not alter the adhesion of C. albicans or the biofilm formed by both species. • Commercially available implant surface with hydroxyapatite nanoparticles reduce the adhesion of Streptococcus sanguinis. • This commercially available surface shows potential in diminishing Streptococcus infections. • A commercially available implant surface coated with hydroxyapatite nanoparticles does not alter C. albicans adhesion. [ABSTRACT FROM AUTHOR]

Amniotic membrane (AM) is an attractive source for bone tissue engineering because of its low immunogenicity, contains biomolecules and proteins, and osteogenic differentiation properties. Hydroxyapatite is widely used as bone scaffolds due to its biocompatibility and bioactivity properties. The aim of this study is to design and fabricate scaffold based on hydroxyapatite-coated decellularized amniotic membrane (DAM-HA) for bone tissue engineering purpose. So human amniotic membranes were collected from healthy donors and decellularized (DAM). Then a hydroxyapatite-coating was created by immersion in 10X SBF, under variable parameters of pH and incubation time. Hydroxyapatite-coating was characterized and the optimal sample was selected. Human adipose-derived mesenchymal stem cell behaviors were assessed on control, amniotic membrane, and coated amniotic membrane. The results of the SEM, MTT assay, and Live-Dead staining showed that DAM and DAM-HA support cell adhesion, viability and proliferation. Osteogenic differentiation was evaluated by assessment of alkaline phosphatase activity and expression of osteogenic markers. Maximum gene expression values compared to control occurred in 14 days for alkalin phosphatase, while the highest values for osteocalcin and osteopontin in 21 days. These gene expression values in DAM and DAM-HA for alkalin phosphatase is 6.41 and 8.47, for osteocalcin is 3.95 and 5.94 and for osteopontin is 5.59 and 9.9 respectively. The results of this study indicated DAM supports the survival and growth of stem cells. Also, addition of hydroxyapatite component to DAM promotes osteogenic differentiation while maintaining viability. Therefore, hydroxyapatite-coated decellularized amniotic membrane can be a promising choice for bone tissue engineering applications. [Display omitted] • Amniotic membrane is a suitable source for bone tissue engineering application. • Prepared a homogeneous hydroxyapatite coating through immersion in 10X SBF. • Hydroxyapatite coated amniotic membrane promoted the viability of the cells. • Hydroxyapatite coated amniotic membrane promotes osteogenic differentiation. [ABSTRACT FROM AUTHOR]

The aim of the present systematic review was to evaluate reported survival rate and marginal bone (MBL) loss of implants with different surface roughness and followed up for 10 years or longer. For the majority of the 62 included clinical studies, no direct comparison between different surfaces was made, thus our report is mainly based on reported survival rates and marginal bone loss for individual implant brands with known surface roughness. The survival rate was 82.9 to 100% for all implants after 10 or more years in function and the marginal bone loss was, on average, less than 2.0 mm for all implant surfaces included, i.e. turned, titanium plasma sprayed (TPS), blasted, anodised, blasted and acid-etched but the turned surface in general demonstrated the smallest MBL. However, the survival rates were in general higher for moderately rough surfaces. The roughest TPS surface demonstrated the highest probability for failure, while the anodised showed the lowest probability. In conclusion, the present systematic review demonstrates that it is possible to achieve very good long- term results with all types of included surfaces. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAp) is an important component of mammal bones and teeth, being widely used in prosthetic implants. Despite the importance of HAp in medicine, several promising applications involving this material (e.g., in photo-catalysis) depend on how well we understand its fundamental properties. Among the ones that are either unknown or not known accurately, we have the electronic band structure and all that relates to it, including the bandgap width. We employ state-of-the-art methodologies, including density hybrid-functional theory and many-body perturbation theory within the dynamically screened single-particle Green’s function approximation, to look at the optoelectronic properties of HAp. These methods are also applied to the calculation of defect levels. We find that the use of a mix of (semi-)local and exact exchange in the exchange-correlation functional brings a drastic improvement to the band structure. Important side effects include improvements in the description of dielectric and optical properties not only involving conduction band (excited) states but also the valence. We find that the highly dispersive conduction band bottom of HAp originates from anti-bonding σ* states along the ⋯OH–OH–⋯ infinite chain, suggesting the formation of a conductive 1D-ice phase. The choice of the exchange-correlation treatment to the calculation of defect levels was also investigated by using the OH-vacancy as a testing model. We find that donor and acceptor transitions obtained within semi-local density functional theory (DFT) differ from those of hybrid-DFT by almost 2 eV. Such a large discrepancy emphasizes the importance of using a high-quality description of the electron-electron interactions in the calculation of electronic and optical transitions of defects in HAp. [ABSTRACT FROM AUTHOR]

A hydroxyapatite (HA) nano-coated polyetheretherketone (PEEK) bone tissue scaffold modified with amoxicillin (AMX) was developed by 3D printing, modified hydrothermal method and impregnation. The morphology of the HA coating and the effect of the coating on mechanical properties, cytocompatibility and antibacterial properties were then investigated. Results found that the morphology of HA coating on the PEEK scaffold could be controlled by adjusting reaction temperature or/and time. Moreover, the HA coatings obtained by reacting at 120 °C, pH 12 for 12 h, were the ordered arrangement of nanorods, similar to the ordered arrangement of HA in natural bone tissue. Mechanical testing results demonstrated no adverse effect of coating and modified process on the inherent mechanical properties of PEEK. Moreover, the compressive yield strength and Young's modulus of the scaffolds were 11.23 ± 0.88 and 129.18 ± 8.10 Mpa, which could meet the mechanical requirements of native bone tissue. The cytocompatibility experiment with rabbit adipose-derived stem cells performed that the fabricated process and scaffolds were non-toxic, and cellular adhesion ability was enhanced after modification. The antibacterial properties of the AMX-modified scaffold were evaluated, and results confirmed that AMX could be loaded on the scaffold and released during cultivation to show excellent antibacterial properties. In conclusion, the fabricated modified HA-coated PEEK scaffold with AMX has great potential as a bone substitute in clinical application. [ABSTRACT FROM AUTHOR]

Porous coatings play a critical role in osseointegration between the artificial joint implant and host bone. Herein, a previously developed hydroxyapatite–silver (HA-Ag) gradient bioactive ceramic coating with a three-layer structure is further improved. Through laser cladding, a bioactive porous ceramic coating was prepared by adding carboxyl multi-walled carbon nanotubes (CMWCNTs) to HA powder. In this study, the effects of the added amount of CMWCNTs on the pore size, porosity, and active substance content were investigated. The results showed that the porous structure of the bioactive surface layer was gradually changed from the round hole shape to the reticular porous shape when the addition amount of CMWCNTs was increased from 5 wt % to 20 wt %, and the most appropriate amount of CMWCNTs was 10 wt %. In addition, the biocompatibility of the porous ceramic coating, as well as its effect on the alkaline phosphatase (ALP) activity of osteoblasts, were evaluated in vitro. Simulated body fluid (SBF) soaking tests were applied to determine the changes in ion concentration and calculate the concentration quotient and transfer free energy of Ca2+ and PO 4 3 − during the soaking period in SBF. The effects of the porous ceramic coating on the nucleation and growth of HA were also validated. The results showed that the preparation of the gradient porous ceramic coating was beneficial to the nucleation and growth of apatite, further improving the bioactivity of the coating to achieve osseointegration between the artificial joint implant and host bone. [ABSTRACT FROM AUTHOR]

Titanium alloys have good biocompatibility and good mechanical properties, making them particularly suitable for dental and orthopedic implants. Improving their osseointegration with human bones is one of the most essential tasks. This can be achieved by developing hydroxyapatite (HA) on the treating surface using the plasma electrolytic oxidation (PEO) method in molten salt. In this study, a coating of titanium oxide-containing HA nanoparticles was formed on Ti-6Al-7Nb alloy by PEO in molten salt. Then, samples were subjected to hydrothermal treatment (HTT) to form HA crystals sized 0.5 to 1 μm. The effect of the current and voltage frequency for the creation of the coating on the morphology, chemical, and phase composition was studied. The anti-corrosion properties of the samples were studied using the potentiodynamic polarization test (PPT) and electrochemical impedance spectroscopy (EIS). An assessment of the morphology of the sample formed at a frequency of 100 Hz shows that the structure of this coating has a uniform submicron porosity, and its surface shows high hydrophilicity and anti-corrosion properties (4.90 × 106 Ohm·cm2). In this work, for the first time, the process of formation of a bioactive coating consisting of titanium oxides and HA was studied by the PEO method in molten salts. [ABSTRACT FROM AUTHOR]

In this study, we attempted to develop a dental caries prevention method using a bioapatite (BioHap), an eggshell-derived apatite with nanoparticle size and biocompatibility, with a high-concentration fluoride tooth surface application method. The enamel acid resistance after the application of the proposed method was compared with that of a conventional topical application of fluoride using bovine tooth enamel as an example. The tooth samples were divided into three groups based on the preventive treatment applied, and an acid challenge was performed. The samples were evaluated for acid resistance using qualitative and quantitative analytical methods. The BioHap group demonstrated reduced enamel loss and improved micro-Vickers hardness, along with a thick coating layer, decreased reaction area depth, and decreased mineral loss value and lesion depth. The combination of BioHap with high-concentration fluoride led to the formation of a thick coating layer on the enamel surface and better suppression of demineralization than the conventional method, both qualitatively and quantitatively. The proposed biocompatible nano-hydroxyapatite coating method is expected to become a new standard for providing professional care to prevent dental caries. [ABSTRACT FROM AUTHOR]

The industrial by-product cadmium can pollute the environment and be harmful to humans after being discharged from wastewater. In this study, a low-cost adsorbent deriving from kitchen waste eggshells (BC), was modified by magnesium-doped hydroxyapatite in order to form a new adsorbent (MHBC) capable of removing Cd2+ from water. When compared to BC, the adsorption capacity of MHBC was found to be greatly improved, while their equilibrium adsorption capacities were 4.82 and 49.41 mg·g–1, respectively. Kinetic, isothermal, and environmental factors’ analyses suggested that chemisorption played a major role in the Cd2+ adsorption process delivered by MHBC. Particularly, chemical complexation, ion exchange, and electrostatic interaction could be the main mechanisms involved. Both the pseudo-second-order kinetics equation and the Sips isotherm model were found to fit the adsorption process well. Sips model revealed that the maximum adsorption capacity of MHBC at 25°C was 68.898 mg·g–1. Acidic conditions and the presence of Mg2+, Pb2+, Cu2+, and Zn2+ were found to reduce the adsorption capacity of MHBC for Cd2+. After three cycles, the removal percentage of Cd2+ by MHBC was still able to reach 78.75%. Therefore, our study suggests that MHBC is a highly efficient, green, and sustainable Cd2+-removing adsorbent. [ABSTRACT FROM AUTHOR]

Background/Aim. The materials used nowadays for bone replacement do not fully meet the requirements for complete regeneration, which is why new ones are being tested. Despite numerous attempts to improve bone tissue regeneration, no fulfilling material has been found yet. This study investigated the influence of poly-lactide-co-glycolide (PLGA) and polyethyleneimine (PEI) as coatings for hydroxyapatite (HAP) bone carriers on bone tissue regenerative potential in rabbits' calvarial defect. Methods. Calvarial defects measuring 6 mm in diameter were made in 19 skeletally mature rabbits. Defects were filled with one of the following materials: PLGA coated HAP (HAP + PLGA), PEI coated HAP (HAP + PEI), and bovine HAP - Bio-Oss® (positive control). Unfilled defects represented negative control. Histological analysis was performed in order to determine the inflammatory response of the host tissue. The formation of the new bone was evaluated using histomorphometric analysis. All analyses have been conducted in samples obtained 3, 6, and 9 weeks after implantation. Results. Three weeks post-implantation, a trend toward increased healing in the HAP + PLGA group compared to other investigated materials was noticed, with no statistically significant difference between the study groups (p > 0.05). However, after 6 and 9 weeks, significant healing was observed in favor of the HAP coated with PLGA compared to other groups (p < 0.05). Within this group, greater bone healing was observed compared to the HAP + PEI and Bio-Oss® groups. Conclusion. PLGA demonstrated greater coating potential compared to PEI with respect to osteogenesis improvement in bone reconstructive surgery. [ABSTRACT FROM AUTHOR]

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

Background: Bioceramic nanometer coatings have been regarded as potential substitutes for plasma-sprayed hydroxyapatite coatings, and the association with bone morphogenetic protein (BMP) is an attempt to achieve faster osseointegration to hasten oral rehabilitation. Objective: This study aimed to investigate the effect of recombinant human bone morphogenetic protein-7 (rhBMP-7) on the osseointegration of titanium implants coated with a thin film surface of hydroxyapatite (HA). Methods: Two implants (n = 24) were placed in each white New Zealand rabbits' femur (n = 6). Implants were placed in the right femur after standard instrumentation (A and B) and in the left femur after an over-instrumentation (C and D), preventing bone-implant contact. The distal implants were installed associated with rhBMP-7 (groups B [regular instrumentation] and D [over-instrumentation]) and, also, in the absence of without BMP (control groups A [regular instrumentation] and C [over-instrumentation]). After 4 weeks, the animals were euthanized. The bone blocks containing the implants were embedded in methyl methacrylate and sectioned parallel to the long axis of the implant, which were analyzed by image segmentation. The data were analyzed using a nonparametric statistical method. Results: We observed that Group A had a mean bone formation of 35.6% compared to Group B, which had 48.6% (p > 0.05). Moreover, this group showed 28.3% of connective tissue compared to Group A, with 39.3%. In the over-instrumented groups, rhBMP-7 (Group D) showed an enhanced and significant increase in bone formation when compared with the group without rhBMP-7 (Group C). Conclusion: We concluded that the association of rhBMP-7 to thin nanostructure HA-coated implants promoted greater new bone area than the same implants in the absence of rhBMP-7, mainly in cases of over-instrumented implant sites. [ABSTRACT FROM AUTHOR]

Percutaneous implants are frequently affected by bacterial growth at the skin-implant interface. Integration between implant and surrounding skin is important to prevent bacteria from spreading to the underlying tissue. The standard method to evaluate skin-implant integration is by histomorphometry on samples which have been placed in tissue grown in vivo or ex vivo. In this study, a biomechanical method was developed and evaluated. The integration of implants into porcine skin was studied in an ex vivo model, where pig skin samples were cultivated in a nutrient solution. Cylindrical shaped implants, consisting of polyether ether ketone (PEEK) and titanium (Ti) with different surface treatments, were implanted in the skin tissue and the skin was grown in nutrient solution for 2 weeks. The implants were then extracted from the implantation site and the mechanical force during extraction was measured as a quantitative assessment of skin-implant integration. Implants from each group were also processed for histomorphometry and the degree of epidermal downgrowth (ED) and tissue to implant contact (TIC) was measured. A higher mean pullout force was observed for the PEEK implants compared to the Ti implants. Applying nanosized hydroxyapatite (HA) on Ti and PEEK increased the pullout force compared to uncoated controls, 24% for machined and 70% for blasted Ti, and 51% for machined PEEK. Treatment of Ti and PEEK with nanosized zirconium phosphate (ZrP) did not increase the pullout force. The histomorphometry analysis showed correlation between ED and pullout force, where the pullout force was inversely proportional to ED. For TIC, no significant differences were observed between the groups of same material (i.e. Ti, Ti+HA, Ti+ZrP, and PEEK, PEEK + HA, PEEK + ZrP), but it was significantly higher for PEEK compared to Ti. Scanning electron microscopy analysis was done on samples before and after the pullout tests, showing that the ZrP coating was unaffected by the 2 week ex vivo implantation and pullout procedure, no dissolution or detachment of the coating was observed. For the HA coating, a loss of coating was seen on approximately 5% of the total surface area of the implant. [ABSTRACT FROM AUTHOR]

In the present paper, the effects of various calcination temperatures of 675, 775, 875, and 975 °C on the structural properties of 0.8 at.% Co-containing hydroxyapatites (HAps) were investigated by using X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis (DTA), and scanning electron microscopy (SEM). A density functional theory (DFT) has been applied to find out the energy band gap and density of states (DOS). It was found that the crystallite size and lattice strain gradually increased with increasing temperature. For each sample, biphasic structure was observed. The phase distribution was affected by the temperature. The significant changes, dependent on the calcination temperature, in the crystallinity percent, stress, and anisotropic energy density values were detected. The functional groups of phosphate and hydroxyl associated with the formation of the HAp phase were detected for each sample. It was observed that the calcination temperature affected the morphology. [ABSTRACT FROM AUTHOR]

A robust superhydrophobic brass mesh was fabricated based on a low-energy surface and a roughness on the nano/micro-meter scale. It was carried out by the forming of hydroxyapatite (HP) coatings on its surface through a constant current electro-deposition process, followed by immersion in fluoroalkylsilane solution. Surface morphology, composition and wetting behavior were investigated by field-emission scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high speed camera, and contact angle goniometer. Under optimal conditions, the resulting brass mesh exhibited superhydrophobicity, excellent anti-corrosion (η = 91.2%), and anti-scaling properties. While the surfactant liquid droplets of tetradecyl trimethyl ammonium bromide (TTAB) with different concentration were dropped on the superhydrophobic surface, maximum droplet rebounding heights and different contact angles (CAs) were observed and measured from side-view imaging. The plots of surfactant-concentration−maximum bounding height/CA were constructed to determine its critical-micelle-concentration (CMC) value. Close CMC results of 1.91 and 2.32 mM based on the determination of maximum rebounding height and CAs were obtained. Compared with its theoretical value of 2.1 mM, the relative errors are 9% and 10%, respectively. This indicated that the novel application based on the maximum rebounding height could be an alternative approach for the CMC determination of other surfactants. [ABSTRACT FROM AUTHOR]

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

Understanding interactions between bone morphogenetic proteins (BMPs) and biomaterials is of great significance in preserving the structure and bioactivity of BMPs when utilized in clinical applications. Currently, bone morphogenetic protein-2 (BMP-2) is one of the most important growth factors in bone tissue engineering; however, atomistic interactions between BMP-2 and zinc-substituted hydroxyapatite (Zn-HAP, commonly used in artificial bone implants) have not been well clarified until now. Thus, in this work, the interaction energies, binding/debinding states, and molecular structures of BMP-2 upon a series of Zn-HAP surfaces (Zn-HAPs, 1 at%, 2.5 at%, 5 at%, and 10 at% substitution) were investigated by hybrid molecular dynamics (MD) and steered molecular dynamics (SMD) simulations. Meanwhile, cellular studies including alkaline phosphatase (ALP) activity and reverse transcription-polymerase chain reaction (RT-PCR) assay were performed to verify the theoretical modeling findings. It was found that, compared to pure HAP, Zn-HAPs exhibited a higher binding affinity of BMP-2 at the adsorption process; meanwhile, the detachment of BMP-2 upon Zn-HAPs was more difficult at the desorption process. In addition, molecular structures of BMP-2 could be well stabilized upon Zn-HAPs, especially for Zn10-HAP (with a 10 at% substitution), which showed both the higher stability of cystine-knots and less change in the secondary structures of BMP-2 than those upon HAP. Cellular studies confirmed that higher ALP activity and osteogenic marker gene expression were achieved upon BMP-2/Zn-HAPs than those upon BMP-2/HAP. These findings verified that Zn-HAPs favor the adsorption of BMP-2 and leverage the bioactivity of BMP-2. Together, this work clarified the interaction mechanisms between BMP-2 and Zn-HAPs at the atom level, which could provide new molecular-level insights into the design of BMP-2-loaded biomaterials for bone tissue engineering. [ABSTRACT FROM AUTHOR]

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

In order to merge high-mechanical properties and suitable bioactivity in a single scaffold, zirconia porous structures are here coated with a hydroxyapatite layer. The digital light processing (DLP) technique is used to fabricate two types of scaffolds: simple lattice structures, with different sizes between struts (750, 900 and 1050 µm), and more complex trabecular ones, these latter designed to better mimic the bone structure. Mechanical tests performed on samples sintered at 1400 °C provided a linear trend with a decrease in the compressive strength by increasing the porosity amount, achieving compressive strengths ranging between 128–177 MPa for lattice scaffolds and 34 MPa for trabecular ones. Scaffolds were successfully coated by dipping the sintered samples in a hydroxyapatite (HA) alcoholic suspension, after optimizing the HA solid loading at 20 wt%. After calcination at 1300 °C, the coating layer, composed of a mixture of HA and β-TCP (β-TriCalcium Phospate) adhered well to the zirconia substrate. The coated samples showed a proper bioactivity, well pronounced after 14 days of immersion into simulated body fluid (SBF), with a more homogeneous apatite layer formation into the trabecular samples compared to the lattice ones. [ABSTRACT FROM AUTHOR]

The hydroxyapatite coating on the metallic implant is preferred to improve biocompatibility and faster bone integration. The reliability of the coating during fixation and after surgery is important to achieve the expected bone growth. The micromotion between the implant and bone due to patient movement causes fretting and deteriorates the coating. New coating techniques are attempted to improve the strength of the HAp coating. The suspension plasma spray (SPS) process is a new process where fine grain-structured coating with controlled porosity can be developed. The fretting wear behavior of titanium (Ti) substrate and SPS-coated HAp on Ti substrate fretted against alumina are discussed in this paper. The relative displacement expected in the bone and stem interface is estimated using numerical studies, and fretting wear experiments are carried out with the maximum relative displacement estimated. Fretting wear tests are performed using the ball-on-flat configuration at different contact stresses. The fretting friction coefficient variation in the coated samples during the initial contact period is different compared to the uncoated samples. A high friction coefficient during the early stages of fretting influences the reliability of the coating, although the steady-state friction coefficient is nearly the same as that of the uncoated titanium. The friction force vs. displacement loops obtained from the tests revealed 'gross-slip' conditions. The wear scar observations using a scanning electron microscope and 3D-profilometer revealed significant damage in coated samples compared to the uncoated titanium samples. The porous nature of the SPS coating and fine wear particles facilitates a smooth layer formation in longer run. [ABSTRACT FROM AUTHOR]

Air plasma spraying (APS) is a common method of producing hydroxyapatite (HA) coatings for alloprosthetic implants. Modification of HA spraying potentially may diminish the risk of inflammation and local infection during bone implantation. Titanium implants were HA coated with different deposition process parameters. HA powder was deposited using APS with axial powder injection at three different distances (100, 120, and 140 mm). The surface morphology of each implant was examined and the direct contact cytotoxicity of each HA coating was evaluated according to norm ISO 10993 5:2009. The response of monocytes to HA was assessed via the activation of transcription nuclear factor. All coatings had a lamellar structure. HA sprayed at a distance of 120 mm showed the highest roughness and little phase change. The analysis of the results of the conducted research showed that plasma-spraying distance during the HA coating process had a negligible impact on biocompatibility. The results obtained for a distance of 120 mm showed a slight increase in the biological properties tested. Moreover, HA coatings sprayed at different distances were not cytotoxic and did not stimulate the NF-kB. Bare titanium was less susceptible to colonization by Staphylococcus aureus than HA-coated surfaces. HA constitutes a potentially good, low-cost, non-cytotoxic material for joint prostheses. [ABSTRACT FROM AUTHOR]

In current medicine, joint revision surgery plays an important role in the treatment of degenerative joint diseases. Infections of the artificial joints are an iatrogenic, accompanying symptom after joint replacement procedures. A new approach is to functionalize the bioactive coatings of the implants by infiltrating them with anti-inflammatory drugs. This work aims at a one-step approach in manufacturing drug-doped, porous hydroxyapatite coatings by high-velocity suspension flame spraying (HVSFS). Thermal exposure of the temperature-sensitive drugs is critical. Therefore, a new process setup, combining one axial and one radial suspension line, is used for coating deposition. The lower dwell time of the suspension in the flame through radial injection helps in controlling the temperature exposition of the contained drug to the flame. Additionally, the influence of the powder morphology, used as a carrier for the drug in the suspension, is investigated by carrying out spray experiments with suspensions from three different granule types. To analyze the temperature exposition within the coating process, fluoresceine was used as a model drug, as the decomposition of the organic, fluorescing molecules can be easily controlled by fluorescence intensity measurements. It could be shown that the deposition of temperature-sensitive organic molecules is possible without degrading the molecular structure by a modified HVSFS process. This knowledge offers new possibilities in the cost-effective one-step manufacturing of functionalized, anti-inflammatory bioceramic coatings on orthopaedic implants. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the role of Silibinin (SIL)-modified Hydroxyapatite coating on osseointegration in diabetes in vivo and in vitro and explore the mechanism of osteogenic differentiation of MC3T3-E1. RT-qPCR, Immunofluorescence, and Western blot were used to measure the expression level of oxidative Stress Indicators and osteogenic markers proteins. Moreover, CCK-8 assay was conducted to detect cell viability in hyperglycemia. Alizarin red staining and alkaline phosphatase staining were used to examine osteogenic function and calcium deposits. The diabetic rat model receive titanium rod implantation was set up successfully and Von-Gieson staining was used to examine femoral bone tissue around titanium rod. Our results showed that intracellular oxidative stress in hyperglycemia was overexpressed, while FoxO1, SIRT1, GPX1, and SOD2 were downregulated. SIL suppressed oxidative stress to promote osteogenic differentiation. Additionally, it was confirmed that SIL promoted osteogenic differentiation of MC3T3-E1 and obviously restored the osseointegration ability of diabetic rats. Further study indicated that SIL exerted its beneficial function through activation SIRT1/SOD2 signaling pathway to restore osteoblast function, and improved the osseointegration and stability of titanium rods in vivo. Our research suggested that the SIL-modulated oxidative Stress inhibition is responsible for the activation of the process of osteogenic differentiation through activation SIRT1/SOD2 signaling pathway in hyperglycemia, providing a novel insight into improving prosthetic osseointegration in diabetic patients. [ABSTRACT FROM AUTHOR]

Composite scaffolds obtained by the combination of biodegradable porous scaffolds and hydroxyapatite with bone regeneration potential are feasible materials for bone tissue engineering. However, most composite scaffolds have been fabricated by complicated procedures or under thermally harsh conditions. We have previously demonstrated that hydroxyapatite coating onto various substrates under a thermally mild condition was achieved by erbium-doped yttrium aluminum garnet (Er: YAG) pulsed laser deposition (PLD). The purpose of this study was to prepare a polycaprolactone (PCL) porous scaffold coated with the hydroxyapatite by the Er: YAG-PLD method. Hydroxyapatite coating by the Er: YAG-PLD method was confirmed by morphology, crystallographic analysis, and surface chemical characterization studies. When cultured on PCL porous scaffold coated with hydroxyapatite, rat bone marrow-derived mesenchymal stem cells adhered, spread, and proliferated well. The micro-CT and staining analyses after the implantation of scaffold into the critical-sized calvaria bone defect in rats indicate that PCL porous scaffold coated with hydroxyapatite demonstrates accelerated and widespread bone formation. In conclusion, PCL porous scaffold coated with hydroxyapatite obtained by the Er: YAG-PLD method is a promising material in bone tissue engineering. [ABSTRACT FROM AUTHOR]

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

An anatase TiO2 coating doped with trace silver and paracetamol components was manufactured via the impregnation method combined with the potentiostatic reduction approach. The surface morphologies, microstructures and components were characterized via many surface analytical technologies. In addition, an electrochemical evaluation approach was developed to assess degradation behaviors of the beneficial chemicals in the phosphate buffer solution (PBS). The results demonstrated that the TiO2 coating was loaded with silver and paracetamol successfully. The Ag-oxy-carbide complex, coming from the reaction of silver ions and with hydroxyl groups in paracetamol, was helpful for the beneficial species sustainedly releasing from the coating during the 18-day immersion and remaining in the coating even after 18-day immersion in the PBS. [ABSTRACT FROM AUTHOR]

With the objective of enhancing the stability of scorodite, its encapsulation with hydroxyapatite (Ca5(PO4)3OH) (HAP) and fluorapatite (Ca5(PO4)3F) (FAP) surface coatings, the two most stable of the calcium phosphates, inert to pH and redox potential variations, are presented in this work. The experimental work includes: (1) determination of the metastable zone for HAP and FAP precipitation, (2) the synthesis of crystalline scorodite under atmospheric conditions using hydrothermal scorodite seed and its characterization, (3) the coating of scorodite with hydroxyapatite and fluorapatite with supersaturation-controlled heterogeneous crystallization, and (4) the long-term stability of the encapsulated scorodite solids. Hydroxyapatite and fluorapatite were prepared with homogeneous precipitation from a metastable solution to which reagents were added at a controlled flow rate. Crystalline scorodite was produced with seeding precipitation and encapsulated with a direct apatite (HAP or FAP) deposition that was controlled by adjusting the pH and reagent addition. The stability tests in oxic and anoxic environments over the pH range of 5–9 showed the release of arsenic from the apatite-coated scorodite to be much lower than from naked scorodite, thereby demonstrating that apatite-based encapsulation of hazardous materials is technically feasible and merits further consideration for development into an arsenic stabilizing technology. [ABSTRACT FROM AUTHOR]