Regulating the properties of carbon dots via a solvent-involved molecule fusion strategy for improved sensing selectivity

Highlights: • A solvent-involved molecular fusion strategy is adopted for the CDs preparation. • The CDs exhibits prominent detection selectivity toward Ag⁺. • The obtained CDs can be used as an effective photoluminescence probe for intercellular Ag⁺ and Cys imaging. -- Abstract: Carbon dots (CDs) were prepared by a solvent-involved molecular fusion strategy using o-phenylenediamine (OPD) as the carbon source and formamide as the reaction solvent. The CDs possessed not only the functional groups inherited from the carbon source and the reaction solvent, but also numerous C=N groups in the structure, resulting from the Schiff base reaction between –NH₂ of OPD and C=O of formamide. These functional groups endowed the final CDs with a favorable soft-base property, leading to the high tolerance level toward hard-acid type metal ions and prominent detection selectivity toward Ag⁺. Moreover, the obtained CDs displayed outstanding biocompatibility and low cytotoxicity, and demonstrated potential as an effective photoluminescence probe for intercellular Ag⁺ and Cys imaging, preventing the interference of autofluorescence from living tissues. This study focused on the solvent-involved molecular fusion strategy could provide new insights into the design of novel carbon-based nanostructures and optimization of the structure-property relationship of CDs.