In situ synthesis of fluorescent polydopamine polymer dots based on Fenton reaction for a multi-sensing platform

The development of fluorescent nanosensors has attracted extensive research interest owing to their superior optoelectronic properties. However, current fluorescent nanoprobes generally involve complicated synthesis processes, background signal disturbance, and limited analyte detection. In this work, a facile and time-saving synthetic strategy for the preparation of green emitting polydopamine polymer dots (PDA-PDs) from dopamine via Fenton reaction at room temperature was proposed for the first time. The obtained PDA-PDs possessed excellent luminescence properties, with a long-wavelength emission of 522 nm, a large Stokes shift of 142 nm, and good photostability against ionic strength and UV irradiation. The formation mechanism of fluorescent PDA-PDs is as follows: in the presence of Fe2+ and H2O2, dopamine could rapidly undergo oxidation to its quinone derivatives and further polymerize to synthesize the fluorescent PDA-PDs with the acceleration of hydroxyl radicals produced from the Fenton reaction. Thus, a versatile turn-on fluorescence sensing method was developed for the detection of multi-analytes (including Fe2+, dopamine, H2O2, and glucose) based on monitoring the intrinsic fluorescence signal of the in situ formation of PDA-PDs. This sensing method could be efficiently applied for the detection of Fe2+, dopamine, and glucose in real human serum samples. Moreover, a three-input AND molecular logic gate based on this sensing platform was designed with the fluorescence signal of PDA-PDs as the gate. Finally, the proposed PDA-PDs could have immense broad prospects in nanomaterials and biosensors.