Fluorescent sensor based on CdTe-QDs @ N-CDs complexes for visual identification of goji berries origin

The price and quality of goji berries (GB) are closely linked to their origins. Therefore, identifying the geographical origins of GB produced in specific origin is important. In this work, a fluorescent sensor based on a glutathione modified quantum dots and nitrogen-doped carbon quantum dots complexes (CdTe-QDs @ N-CDs) with an internal filtration effect (IFE) was constructed to visual identify the origin of GB. The phenolic acid compounds in GB could quench the fluorescence of QDs and CDs through the photoinduced electron transfer (PET) and the aggregation-induced quenching (ACQ), respectively. Due to the different contents of phenolic acid in GB from different origins, the fluorescent sensor based on CdTe-QDs @ N-CDs complexes could produce distinct and different fluorescent colors, from orange to blue under the dual reaction. Finally, partial least squares discriminant analysis (PLS-DA) model was applied to establish classification models for identifying the geographical origin of GB based on the fluorescent colors. The results showed that the accuracy of GB visual recognition could be increased from 68.9% to 93.3%. This proven that the proposed strategy has excellent potentials for identification of the geographical origins of GB.