PEEK-based implant materials have gained increasing attention as an alternative to titanium due to their biocompatibility and bone-like elasticity. However, PEEK’s surface quality and wear resistance are lower than those of metals. This study aimed to enhance the bioactivity and surface quality of PEEK by coating it with silver and copper nanoparticles synthesized via a green method using Equisetum telmateia Ehrh. extract. PEEK samples (Ø 25 mm, 3 mm thick) were coated with single and double layers using spray (airbrush-spray) and drop-coating methods. Comprehensive analyses including SEM, EDX, FT-IR, UV-Vis, surface roughness, release studies, antioxidant and cytotoxicity activity, and antibacterial tests were conducted on the coated samples. The results demonstrated that AgNPs and CuNPs coatings significantly improved the surface quality of PEEK. SEM analysis revealed particle sizes ranging from 48 to 160 nm for AgNPs and 50–135 nm for CuNPs, with superior dispersion obtained using the airbrush-spray method. Surface roughness measurements showed a reduction of 17–33% for AgNPs-coated samples and 7–15% for CuNPs-coated samples compared to uncoated PEEK, with airbrush-spray coatings providing smoother surfaces. Antioxidant activity tests indicated that AgNPs provided 35% higher antioxidant activity compared to CuNPs. Additionally, antibacterial tests revealed that AgNPs exhibited a higher zone of inhibition (up to 14 mm for S. aureus and 18 mm for E. coli) compared to CuNPs, which exhibited zones of 8 mm and 10 mm, respectively. This study concludes that green-synthesized AgNPs, in particular, enhance the bioactivity and surface properties of PEEK, making it a promising material for biomedical applications such as infection-resistant implants.

In this study, a novel multifunctional copper nanoparticle CuNPs in the organic biomatrix was coated to the surface of Ti6Al4V to create multifunctional features. The synthesis of CuNPs was carried out by plant-mediated green synthesis method obtained from Moringa leaf extract, and the prepared CuNPs were coated on the substrate surfaces as single and double layers with drop casting methods. Characterizations of the synthesized CuNPs were performed by UV–Vis, FTIR, XRD, and SEM methods. Characterization of the modified Ti6Al4V alloy surfaces was performed using SEM-EDS and surface roughness analysis. The electrochemical corrosion, antibacterial behavior, and cytotoxic effects of coated and noncoated Ti6Al4V as a function of biocompatibility properties were also tested. The synthesized CuNPs have a homogeneously dispersed spherical shape. Biocorrosion tests have clearly demonstrated that the coating forms a protective film on the substrate surface, and the resistance increased by 49 %. Antibacterial results show that the single and double-coated Ti6Al4V alloy samples with CuNPs organic nanostructure had improved biocompatibility. However, it was determined that the cytotoxic effect increases proportionally with the coating. The obtained results show the importance of surface modification in the appropriate nanostructure to obtain multifunctional nanoplatforms that show promise in biomedical applications.

Polylactic acid (PLA) is an eco-friendly polymer known for its biodegradability and biocompatibility, yet its properties are sensitive to recycling and sterilization. These processes may cause chain scission and structural irregularities, leading to reduced strength, brittleness, or unpredictable deformation. In this study, PLA and recycled PLA (Re-PLA) specimens were produced by FDM 3D printing with different infill rates (25%, 50%, 75%), layer thicknesses (0.15, 0.20, 0.25 mm), and printing orientations (0°, 45°, 90°). Steam sterilization at 121 °C and 1 bar for 15 min simulated biomedical conditions. Mechanical, surface, degradation, and biocompatibility properties were examined using three-point bending, roughness measurements, SEM, and cell viability tests. Results showed that infill rate was the main parameter affecting flexural strength and surface quality, while orientation increased roughness. Sterilization and recycling made deformation less predictable, particularly in St-Re-PLA. SEM revealed stronger bonding at higher infill, but more brittle fractures in PLA and Re-PLA, while sterilized specimens showed ductile features. No visible degradation occurred at any infill level. Regression analysis confirmed that second-order polynomial models effectively predicted flexural strength, with layer thickness being most influential. These findings provide critical insights into optimizing PLA and Re-PLA processing for biomedical applications, particularly in the production of sterilizable and recyclable implantable devices.