Enhanced Photocatalytic Activity of Acerola Peel Extract-Coated TiO2 Against Pseudomonas aeruginosa

TiO2 is a widely studied semiconductor with high photocatalytic activity, with various applications across many sectors. TiO2 oxidative reactions are only driven under ultraviolet radiation, and expanding the absorption properties towards to the visible range could enhance the photocatalytic applications, reducing its UV light source reliance. In this context, this study reports the titanium dioxide nanoparticles (TiO2-NPs) coating with Malpighia emarginata (acerola) extract to shift the band gap and be applied against Pseudomonas aeruginosa by photocatalysis. The acerola peel hydroethanolic extract (AcE) was obtained by ultrasound, evaluating its total flavonoid and phenolic compound contents, scavenging free radical ability, and antimicrobial capacity. AcE coating of TiO2-NPs was obtained under magnetic stirring (AcE-TiO2-ms) and ultrasound bath (AcE-TiO2-us) methods. Nanoparticles (NPs) physicochemical properties were characterized by UV-visible DRS spectroscopy, Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopic (TEM), and atomic force microscopy (AFM) techniques. The NPs antimicrobial activity was assessed through photocatalysis under dark, visible, and UV light conditions for 30–180 min. The AcE exhibited high phenolic compound content, antioxidant activity, and antimicrobial potential against P. aeruginosa. The AcE coating TiO2-NPs resulted in an average particle size of 20–35 nm, confirmed by FTIR and TEM analyses. Notably, an enhancement in the photocatalytic performance of AcE-coated TiO2 was observed under the visible light spectrum, particularly in the AcE-TiO2-ms case. This nanoparticle exhibited high antimicrobial activity under visible irradiation at 120 and 180 min, confirming its catalytic performance under visible light.