A silicon-doped carbon dot-based multivariate fluorometric and colorimetric probe for the simultaneous detection of heavy metal ions and dopamine

The effective and accurate determination of heavy metals and significant biomolecules is crucial for environmental protection and human health. A novel carbon dot (Si-CDs)-based multivariate sensing method was established for monitoring Cu2+, Mn2+, Co2+ and dopamine (DA) concomitantly. The Si-doped CDs were favorably synthesized using p-phenylenediamine (PPD) and (3-aminopropyl) trimethoxysilane (APTMS) as precursors with a quantum yield of 23.3% and a lifetime of 23.4 mu s. The optimal emission of Si-CDs was determined at 500 nm with an excitation at 390 nm with an excellent aqueous dispersibility and environmental tolerance. Moreover, the proposed Si-CDs exhibited sensitive FL quenching toward Cu2+, Mn2+ and DA, and a colorimetric response towards Co2+, thus a multiple dual-mode sensing platform was constructed. The similar FL responses for Cu2+, Mn2+ and DA could be distinguished by different colorimetric variations, which enabled the multivariate detection of these three analytes via dual-mode FL and colorimetric integration. Also, the colorimetric mode that solely recognized Co2+ also realized an excellent linearity correlation between absorption and concentration. Furthermore, the heavy metals in real water samples and DA in serum could be quickly and directly analyzed by visual detection with reliable accuracy. To the best of our knowledge, this is the first report based on CDs for the simultaneous detection of three heavy metal ions and DA by a dual-mode method, opening a new avenue for the ultrasensitive sensing of multiple metal ions and biomolecules in environment protection and biomedical fields. A schematic illustration of the synthesis of Si-CDs and the fluorometric and colorimetric multivariate sensing of Cu2+, Mn2+, Co2+, and DA.