Regulating the photoelectric properties of porphyrin-based COF nanozymes by pillararene with polyphenol structure for efficient photo-enhanced antibacterial effect

Abstract

Nanozymes show great potential as alternatives to natural enzymes. Covalent organic frameworks (COFs) have attracted huge attention for the design of nanozymes due to their unique structures and intriguing properties. Incorporation of appropriate building blocks into COFs can endow them with specific properties, allowing the possibility to design highly efficient COF-based nanozymes. Herein, a heteroporous COF (COF-P5–OH–Fe) was designed and constructed by introducing pillar[5]arenes with polyphenol structures into the porphyrin-based COFs through post-modification strategies, and subsequently, Fe was further modified on the COFs through coordination. The obtained COF-P5–OH–Fe nanozyme showed outstanding peroxidase-like activity, the catalytic activity of which could be enhanced efficiently under light irradiation. The unique polyphenol motif of pillar[5]arenes endows COF-P5–OH–Fe with a narrow energy band gap and enhanced photocurrent and improves the circulation of Fe³⁺/Fe²⁺. As a result, the activity of COF-P5–OH–Fe nanozyme was enhanced to generate reactive oxygen species, enabling efficient antibacterial action. In particular, the absorption wavelength of the COF-P5–OH–Fe nanozyme, which was around 986 nm, enabled it to exhibit superior photo-enhanced bactericidal activity under near-infrared light irradiation. Furthermore, the antibacterial mechanism was also investigated by genome-wide transcriptome analysis using RNA sequencing.