Gold Nanocluster-Encapsulated Hyperbranched Polyethyleneimine for Selective and Ratiometric Dopamine Analyses by Enhanced Self-Polymerization

The exploitation of selective and sensitive dopamine (DA) sensors is essential to more deeply understand its biological function and diagnosis of related diseases. In this study, gold nanocluster-encapsulated hyperbranched polyethyleneimine (hPEI-Au NCs) has been explored as the specific and ratiometric DA nanoprobe through hPEI-assisted DA self-polymerization reactions. The Au NCs encapsulation not only provides a fluorescent internal reference but also enhances the DA self-polymerization by weakening the proton sponge effect of the hPEI layer. Rapid and sensitive DA detection is realized through the proposed hPEI-Au NC nanoprobe with a limit of detection of 10 nM. The favorable selectivity over other possible interferents including amino acids, sugars, and salts is due to the specific self-polymerization reaction. The DA analysis in urine samples with small relative standard deviations has been accomplished with an hPEI-Au NC nanoprobe.