N,S,P Co-Doped Carbon Nanodot Fabricated from Waste Microorganism and Its Application for Label-Free Recognition of Manganese(VII) and l-Ascorbic Acid and AND Logic Gate Operation.

A novel fluorescent probe based on N,S,P codoped carbon nanodots (N,S,P-CNDSac) is very simple and quickly fabricated by a one-step hydrothermal pyrolysis of Saccharomyces cerevisiae and utilized for label-free and "on-off-on" sequential detection of manganese(VII) and l-ascorbic acid (l-AA). The fluorescence of N,S,P-CNDSac can be effectively quenched by Mn(VII) based on an inner filter effect (IFE) and recovered upon the addition of l-AA due to the easy conversion of Mn(VII) to reduced states (i.e., Mn(IV), Mn(II), and Mn(0)) by l-AA. This probe exhibited favorable selectivity and sensitivity toward Mn(VII) and l-AA with detection limits of 50 nmol/L and 1.2 μmol/L, respectively. Simultaneously, an "AND" logic gate based on the as-fabricated N,S,P-CNDSac has been constructed. Also, the as-proposed fluorescent probe was extended to detect Mn(VII) and l-AA in biosystems. Furthermore, the as-constructed fluorescent probe system was successfully applied to the analyses of Mn(VII) in tap water, Fenhe River water, and medicinal herb samples with satisfactory results. The proposed method is simple and easily accessible, demonstrating the great potential of N,S,P-CNDSac in biosensing, disease diagnosis, cellular labeling, and environmental monitoring.