The development of new antibacterial coating (against Escherichia coli and Staphylococcus aureus) with the use of a natural dye (curcumin) and epoxidized soybean oil, according to a photochemistry process has been investigated. Curcumin has been used both as a photosensitizer and an antibacterial agent under visible light illumination. The photoinduced coatings show good adherence properties on an inox substrate and a high thermal stability to 375 °C. Under visible light activation, singlet oxygen (¹O₂) could be generated from the curcumin derivative-coatings, thus inhibiting by 99% and 95% the growth of Staphylococcus aureus and Escherichia coli, respectively, even after 48 h of incubation.

A performing photoinitiating system based on paprika spice was developed (i) to efficiently initiate, according to a green photoinduced process, the cationic polymerization of a biosourced and renewable monomer, e.g., gallic acid, and (ii) to synthesize environmentally friendly antibacterial coatings in a reduced time. A decrease of 100% of the adhered bacteria was demonstrated upon visible light illumination without any remaining live bacteria.

The development of new antibacterial coatings (against Escherichia coli and Staphylococcus aureus) using a natural dye, quercetin, according to a green chemistry process was investigated. Quercetin was used as both a photosensitizer and antibacterial agent. The synthesized material was developed according to a cationic photopolymerization process under light irradiation. The photosensitizing mechanism involving quercetin and an iodonium-based cationic photoinitiator was described for the first time according to steady state photolysis and fluorescence experiments. The resulting coatings showed excellent adhesion on a stainless steel plate as demonstrated by nanoindentation and scratch tests, with a high thermal stability up to 375 °C. Finally, a primary investigation was conducted to assess the antibacterial properties of the glycerol-derived coatings against Escherichia coli and Staphylococcus aureus under light illumination. Electron paramagnetic resonance spectroscopy confirmed the generation of reactive oxygen species, such as singlet oxygen, which is responsible for inhibiting bacteria proliferation.

Phthalocyanines present excellent photochemical properties for use as photoinitiators under visible or IR light exposure.