Signal-on photoluminescent detection of dopamine with carbon dots-MnO2 nanosheets platform based on inner filter effect

Development of new methods for dopamine (DA) assay has attracted continuous attention because it serves a vital role in clinical treatment of neurological diseases such as depression, schizophrenia, and Parkinson's disease. Herein, we design a carbon dots (CDs)-MnO2 nanosheets platform for rapid and sensitive detection of DA in pharmaceutical products. The photoluminescence of CDs can be quenched by MnO2 nanosheets via inner filter effect (IFE) because the absorption of MnO2 nanosheets fully covered the excitation and emission bands of CDs. However, DA can transform MnO2 nanosheets into Mn2+ ions, resulting in the elimination of the IFE and recovery of the photoluminescent signal. This sensing platform shows a selective and sensitive response to DA in the range of 1–30 μM, with a detection limit of 100 nM. The presented IFE-based strategy gives a new insight on development of label-free, selective and sensitive optical methods for drug assay. [Display omitted] •A turn-on fluorescent sensing method is developed for dopamine based on the mechanism of inner filter effect (IFE).•Carbon dots and MnO2 nanosheets with good spectral overlap are fluorophore and absorber in the IFE, respectively.•Inhibition of IFE and fluorescence restoration can be achieved through the decomposition of MnO2 nanosheets by dopamine.•This simple, rapid and label-free method has been applied for quality control of dopamine in drugs.