A novel highly fluorescent S, N, O co-doped carbon dots for biosensing and bioimaging of copper ions in live cells.In this study, novel highly fluorescent sulfur, nitrogen, and oxygen co-doped carbon dots (S, N, O-CDs) were prepared from m-phenylenediamine and sulfamide by using the hydrothermal method.  Furthermore, on account of strong complexation between Cu2+ and pyrophosphate ion (PPi) as well as specific hydrolysis ability of alkaline phosphatase (ALP) towards PPi, PPi and ALP were further detected with high selectivity based on S, N, O-CDs/Cu2+ system. 
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