Perylene-Derived Hydrophilic Carbon Dots with Polychromatic Emissions as Superior Bioimaging and NIR-Responsive Photothermal Bactericidal Agent

Abstract

Little progress has been achieved on the synthesis of hydrophilic carbon dots (CDs), derived from polycyclic aromatic hydrocarbons, as an excellent photothermal agent. In this study, a strategy was developed to synthesize highly photoluminescent greenish-yellow emissive CDs based on nitration followed by hydrothermal carbonization of the polycyclic aromatic hydrocarbon precursor, perylene. The perylene-derived CDs (PY-CDs) exhibited an excellent NIR-light (808 nm) harvesting property toward high photothermal conversion efficiency (PCE = similar to 56.7%) and thus demonstrated remarkable NIR-light responsive photothermal bactericidal performance. Furthermore, these fluorescent PY-CD nanoprobes displayed excitation-dependent polychromatic emissions in the range of 538-600 nm, with the maximum emission at 538 nm. This enables intense multicolor biological imaging of cellular substances with long-term photostability, nontoxicity, and effective subcellular distribution. The bactericidal action of PY-CDs is likely due to the elevated reactive oxygen species amplification in cooperation with the hyperthermia effect. This study offers a potential substitute for multicolor imaging-guided metal-free carbon-based photothermal therapy.