Strongly green fluorescent carbon dots (CQDs) have been directly synthesized from 2,4-diaminophenylhydrazine and 2-hydroxy-5-methylisophthalaldehyde through a facile solvothermal method. The novel CQDs exhibit high fluorescence quantum yield and excellent water solubility due to the abundant amino and hydroxy groups on their surface. The use of the as-prepared CQDs combined with Cu(2+) constructed a "turn-on" switch cysteine-responsive nanoprobe. In the CQDs-Cu(2+) assemblies, the binding of Cu(2+) to CQDs results in the fluorescence quenching of CQDs by electron transfer mechanism, while the ...
