Bio-inspired antibacterial polymer coatings with included silver nanoparticles and porphyrin-based photosensitizer

In this work, we have prepared novel bio-inspired photoactive antibacterial polymer coatings on stainless steel (SS), which possess good mechanical and antibacterial properties. The formation of the photoactive antibacterial polymer coatings consists of the sequential deposition of three components on SS substrate (1) a catechol-based cationic glue P(mDOPA)-co-P(DMAEMA+) used as a universal primer, which facilitates the strong anchoring to SS; (2) a silver loaded (Pox(mDOPA)-Ag0/PAH) nanogel decorated with o-quinones applied to enhance the antibacterial properties of the coating and to permit the covalent grafting of the photosensitizer, and (3) an ethylene diamine derivative of protoporphyrin IX (PPIX-ED). Porphyrins are widely recognized for their antibacterial activity by producing reactive oxygen species when exposed to visible light. To estimate the deposition of the components on the SS substrate, SEM-EDX elemental mapping analysis was applied. Scratch test, nanoindentation, and accelerated property mapping (XPM) analysis were used to assess the mechanical properties of the coatings. The established antibacterial activity of the prepared photoactive polymer coatings on SS against Gram-positive B. subtilis and Gram-negative E. coli strains demonstrates their potential applications in medical and biomedical fields.