Self-assembled photosensitive carbon nanocrystals with broad-spectrum antibacterial bioactivity

Abstract

Self-assembled nanocrystals are promising organic nanomaterials because of their degradability, low toxicity, and environmental friendliness. This work reported a new type of self-assembled photosensitive carbon nanocrystals (SPCNs) synthesized from o-phenylenediamine and L-cysteine. The macromolecules aggregated through carbonization to form carbon dots and then formed stable spiral nanorings through π–π stacking and disulfide bonds. Intriguingly, these nanorings further assembled into tetragonal SPCNs through hydrogen bonding. The aggregation-enhanced photoluminescence (PL) and variable fluorescence spectra reveal that hydrogen bonds are the crucial force for the self-assembly of sprial nanorings to tetragonal SPCNs. In addition, SPCNs can generate ¹O₂, O₂˙⁻, and ˙OH via proton and electron transfer under visible light irradiation, which endows SPCNs with potent and broad-spectrum antibacterial bioactivity. Taking R. solanacearum as a research model, we found that SPCNs can effectively inhibit R. solanacearum bioactivity. Transcriptome analysis revealed that SPCNs suppressed the bioactivity of R. solanacearum by disrupting membrane structure, redox, histidine, and chemotaxis metabolism pathway.