Porphyrin structure carbon dots under red light irradiation for bacterial inactivation

Abstract

Herein, novel carbon dots (CDs) with efficient antibacterial activity are prepared by a simple cyclization reaction of 4-formylbenzoic acid and pyrrole and cross-linking with p-phenylenediamine at room temperature. The CDs exhibit the fluorescence property of red emission, greatly reducing the noise interference from bacterial autofluorescence in fluorescence imaging. At the same time, the CDs with the feature of red absorption facilitate the achievement of light excitation of deep tissues in the living body. Owing to the introduction of the porphyrin ring structure as a photosensitizer, the CDs are able to trigger the generation of singlet oxygen. When excited by a 638 nm laser and irradiated for 20 min, 10 μg mL⁻¹ CDs can achieve complete bacterial extinction. Laser confocal microscopy imaging further demonstrates that the CDs act on the outside of bacteria and generate reactive oxygen species under red light irradiation, providing a non-multidrug resistant sterilization method.