Surface modification of 316L stainless steel with multifunctional locust gum/polyethylene glycol-silver nanoparticles using different coating methods

316 L stainless steel (SS316L) has attracted significant attention in both implantable and non-implantable medical devices for its biocompatibility. However, bacterial adhesion on the surface of SS316L and corrosion after contact with body fluids challenge its usability as a bioimplant. It is therefore necessary to improve the antibacterial and anticorrosion properties of SS316L. One of the most effective ways to achieve this is to deposit a protective metal nanoparticles-based coating on the surface of SS316L. In this study, organic Locust Gum/ polyethylene glycol-silver nanoparticles (Loc/PEG-Ag NPs) were synthesized with sonochemical method, and characterized to determine their morphology, crystal structure, chemical functional groups, and antioxidant capacity. The synthesized Ag NPs were coated on SS316L with drop casting and airbrush spray coating methods. The morphological characteristics, superficial properties, antibacterial activity, and corrosion resistivity of the surface modified SS316L were evaluated. A multifaceted investigation was performed to understand the surface characteristics and to improve the productivity of the Ag NPs coating on the metallic surface. The antioxidant capacities of the spherical-shaped Loc/PEG-Ag NPs with an average size of 10 to 50 nm were found to be 17.90 +/- 0.50 and 20.47 +/- 0.19 mmol Trolox equivalent (TE)(g-1), respectively. The airbrush spray coating treatment significantly improved the surface properties of the substrate due to the formation of a thin layer (8.47 mu m), affecting interactions between Ag NPs and substrates. The Ag NPs coated SS316L demonstrated high antibacterial activity against E. coli and S. aureus at a diameter of 28 mm and 19 mm, respectively. Compared with the bare substrate, the corrosion resistance of the surface modified SS316L is improved. The results illustrated the importance of surface nano-modification in attaining favorable antibacterial and anticorrosive performance. It is believed that the Loc/PEG-Ag NPs coated SS316L could be a promising multifunctional (i.e., uniform coating +biological activity +corrosion resistance) nanoplatforms in biomedical applications.