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This study develops an environmentally friendly novel thermochemical surface modification process of Ti64 alloy by utilizing citric acid and hydrogen peroxide to improve the mechanical properties, biocompatibility, and bioactivity for biomedical applications. The novel process was developed thermochemically, followed by simulated mineralization in Hanks Balanced Salt Solution (HBSS). The study investigates the effects of thermochemicals on surface characteristics by evaluating the influence of eco-friendly chemicals on modifying surfaces and finding the optimal pH value. The findings demonstrated that the modification effectively enhanced the Ti64 alloy mechanical properties with a significant increase in average microhardness by approximately 71 % and a reduction in wear rate by approximately 64.29 %, compared to untreated Ti64 alloy. The surface modification with pH (5,7, and 9) revealed absorptive properties as evidenced by a contact angle below 90°, indicating a hydrophilic surface, enhancing cells' attachment to biomaterials. After soaking Ti64 alloy in HBSS, a uniform coating layer of around 20.5 μm formed, leading to increased bioactivity, as evidenced by a Ca/P ratio of 1.67, comparable to hydroxyapatite in human bone. The hemolysis ratio of 0.027 % at pH 7 indicates little red blood cell (RBC) lysis, indicating increased biocompatibility. The corrosion rate was enhanced with pH (5,7, and 9) approximately (1.975 × 10−2, 1.078 × 10−2, and 1.615 × 10−2) mm/year, respectively. These findings indicate that the novel process with neutral pH (7) is optimal for surface modification as it is the most effective in enhancing the biocompatibility and bioactivity of the Ti64 alloy, making it suitable for biomedical implants. [Display omitted] • Developed a novel eco-friendly thermochemical process using citric acid and hydrogen peroxide to enhance Ti64 alloy surfaces. • The novel process improves the average microhardness by approximately 71 %. • The novel process improves biocompatibility with a hemolysis ratio of 0.027 % with a neutral pH level (7). • The novel process improved the Ti64 alloy wear rate by 64.29 % compared to untreated alloy. [ABSTRACT FROM AUTHOR]

[Display omitted] Recently we have proposed the electropolymerized coating for steel 316L obtained via our patented experimental set and here we provide the study concerning further functionalization of the coating with: 1) COOH groups resulting from acrylic acid in situ electropolymerization, and 2) grafting polymeric coating functionalized with COOH with adhesive peptide including REDV (arginine-glutamic acid-aspartic acid-valine) sequence. Bare steel and the materials with polymeric coating variants with and without REDV were then subjected to HMEC-1 (human dermal microvascular endothelial cells) culture. Surface of the materials were analysed in terms of roughness, wettability, and chemical composition with XPS. It was indicated that COOH content expectedly varied with concentration of acrylic acid used to the functionalization and that REDV grafting for each concentration was successful. We drawn correlations between adhered cells number and surface roughness parameters and contact angle values for each variant. Low contact angle representing hydrophilic character of the surface is beneficial for this type of materials. However, there is a synergistic effect of roughness, wettability, and chemical composition of the material on cells adhesion and one cannot be considered with omission of others. With increasing peptide concentration, wettability first decreases then increases so that optimal peptide content has to be determined. [ABSTRACT FROM AUTHOR]

In this article, we present graphene oxide (produced by a modified Hummers' method) coatings obtained using two different methods: electrophoretic deposition on 316L stainless steel and chemical modification of the surface of gold applied to the steel. The coating properties were characterized by microscopic and spectrometric techniques. The contact angle was also determined, ranging from 50° to 70°. Our results indicated that GO coatings on steel and gold were not toxic towards L929 cells in a direct cell adhesion test—on all tested materials, it was possible to observe the growth of L929 cells during 48 h of culture. The lack of toxic effect on cells was also confirmed in two viability tests, XTT and MTT. For most of the tested materials, the cell viability was above 70%. They showed that the stability of the coating is the crucial factor for such GO coatings, and prove that GO in the form of coating is non-toxic; however, it can show toxicity if detached from the surface. The obtained materials also did not show any hemolytic properties, as the percentage of hemolysis was on the level of the negative control, which is very promising in the light of future potential applications. [ABSTRACT FROM AUTHOR]

Bioactive coatings on VT1-0 commercially pure titanium were formed by the plasma electrolytic oxidation (PEO). A study of the morphological features of coatings was carried out using scanning electron microscopy. A composition of formed coatings was investigated using energy-dispersive spectroscopy and X-ray diffractometry analysis. It was shown that PEO-coatings have calcium phosphate in their composition, which increases the bioactivity of the surface layer. Electrochemical properties of the samples were studied by potentiondynamic polarization and electrochemical impedance spectroscopy in different physiological media: simulated body fluid and minimum essential medium. The data of electrochemical studies indicate more than 15 times decrease in the corrosion current density for the sample with coating (5.0 × 10−9 A/cm2) as compared to the bare titanium (7.7 × 10−8 A/cm2). The formed PEO-layers have elastoplastic properties close to human bone (12–30 GPa) and a lower friction coefficient in comparison with bare metal. The wettability of PEO-layers increased. The contact angle for formed coatings reduced by more than 60° in comparison with bare metal (from 73° for titanium to 8° for PEO-coating). Such an increase in surface hydrophilicity contributes to the greater biocompatibility of the formed coating in comparison with commercially pure titanium. PEO can be prospective as a method for improving titanium surface bioactivity. [ABSTRACT FROM AUTHOR]