A dual-channel sensor array for discrimination of biothiols based on manganese dioxide nanosheets

A dual-signal sensor array for highly sensitive identification of biothiols is reported based on different optical responses of MnO₂/curcumin (CUR) system to different biothiols. The addition of MnO₂ nanosheets (MnO₂ NSs) quenches the fluorescence of CUR, and the color of the mixture changes from yellow to brown. In the presence of reductive biothiols, MnO₂ NSs are etched and lose their fluorescence quenching ability, resulting in an increase in the fluorescence intensity of CUR at 540 nm and a decrease in the absorbance at 430 nm. The sensor array generates specific response modes based on the varying reduction abilities of different biothiols, which can be distinguished by linear discriminant analysis (LDA). The sensor array successfully distinguished five biothiols (glutathione (GSH), dithiothreitol (DTT), cysteine (Cys), mercaptoethanol (ME), and homocysteine (Hcy)) across a wide concentration range (1 μM-100 μM) and biothiol mixtures with varing molar ratios.