A dual-signal optical sensing platform of CDs–MnO2 NS composites for facile detection of ascorbic acid based on a combination of Tyndall effect scattering and fluorescence

Abstract

A dual-signal optical sensing platform was successfully developed for the determination of ascorbic acid (AA) based on blue fluorescent carbon dots (CDs) and manganese dioxide nanosheets (MnO₂ NSs) with strong Tyndall effect (TE) scattering and fluorescence quenching capabilities. In this nanosystem, CDs–MnO₂ NS composites were employed as probes to evaluate the AA concentration. Owing to the strong reduction, the presence of the target AA could reduce the MnO₂ NSs to Mn²⁺ and induce the degradation of the MnO₂ NSs, resulting in a significant decrease in the TE scattering intensity of the MnO₂ NSs and the fluorescence recovery of the CDs. Therefore, a novel optical sensor based on TE scattering and fluorescence dual detectors was developed for the sensitive determination of AA. Under optimized conditions, the limits of detection (LODs) of the two modes were 113 and 3 nM, respectively. Furthermore, the dual-signal optical sensing platform was successfully applied for the detection of AA in human serum.