Applying Carbon Dots-Metal Ions Ensembles as a Multichannel Fluorescent Sensor Array: Detection and Discrimination of Phosphate Anions

Fluorescent carbon dots (CDs) are attracting much attention in sensing recently thanks to their superior optical properties and abundant surface functional groups. To take further advantages of these unique features, CDs are considered to be possible for facilely fabricating multichannel sensor arrays. As a proof-of-concept research, CDs-metal ions ensembles are screened and designed as a triple-channel fluorescent sensor array in this study for the identification of various phosphate anions (e.g., ATP, ADP, AMP, PPi, and Pi) for the first time. Further studies reveal that the selected three metal ions (i.e., Ce3+, Fe3+, and Cu2+) could induce aggregation of the CDs, resulting in quenching of their fluorescence. However, disaggregation or further aggregation of the CDs-metal ions ensembles occurs with the addition of phosphate anions. Consequently, fluorescence of the CDs is recovering or further quenching. On account of various numbers of phosphate group and steric hindrance effects of phosphate anions, their affinities to the sensor array can be distinguished through fluorescence changes of the CDs-metal ions ensembles. By means of statistical analysis methods, the as-developed array is shown excellent capabilities in the detection and discrimination of phosphate anions. Furthermore, practicability of the sensor array is validated by the successful identification of phosphates in serum and blind samples. Compared to previous reports, the as-developed multichannel sensor array manifests numerous advantages, such as simple fabrication process, flexible adjusting detection ranges, and possible extension to other analytes having similar chemical structures or properties.