Ultrathin Cd-3,5-PDC nanosheets enhanced NAP fluorescence probe for visualized detection of peroxynitrite

Abstract

Highly selective and sensitive monitoring of peroxynitrite (ONOO-) in living systems is of significance since it is closely related with the occurrence of multiple diseases. Herein, we successfully constructed ultrathin NAP@Cd-3,5-PDC (NAP@Cd-3,5-PDC-NS, NAP: 2-(6-(4-methylpiperazin-1-yl)− 1,3-dioxo-1 H-benzo[de]isoquinolin-2(3 H)-yl) acetic acid, 3,5-PDC = 3,5-pyridine dicarboxylic acid) fluorescent nanosheets through a simple solution route and subsequent ultrasonication at room temperature. Experiments revealed that the presence of Cd-3,5-PDC-NS significantly enhanced the fluorescence emission of NAP. Under excitation of 398 nm light, the as-obtained NAP@Cd-3,5-PDC-NS could emit about 7-fold stronger photoluminescence than NAP with an equivalent concentration. Also, the as-obtained composite nanosheets could be stably dispersed in phosphate buffer solution (PBS) for 42 days without obvious structure and fluorescence changes. Intriguingly, the strong fluorescence of NAP@Cd-3,5-PDC-NS could be severely quenched by ONOO- without interferences from some other active species, anions/cations, and amino acids. The detection limit of NAP@Cd-3,5-PDC-NS for ONOO- was as low as 61.5 nM, which was 15 times lower than that of the NAP probe alone. Moreover, the as-obtained fluorescent probe could be applied to HepG2 cell imaging, showing its potential application in disease diagnosis.