Oxidization-driven polyamine probe boosts biosensor selectivity via a proton sponge effect regulation strategy

The multi-role characteristics, including neuron communication and brain disease cure, make the selective recognition of Levodopa (DOPA) significant to the deep understanding of its biological functions. However, the interferences from its analogues are difficult to be eliminated. In this contribution, we have developed a proton sponge effect-regulated reactivity probe for achieving selective DOPA recognition based on oxidized hyperbranched polyethyleneimine (hPEI_ox). It is disclosed that the oxidation-boosted biosensor selectivity is attributed to the fact that oxidation-weakened proton sponge effect inhibits the proton adsorption and increases the electron density of polyamine backbone, which facilitates the DOPA approaching and promotes the subsequent self-polymerization reaction to form fluorescent species. With the proposed hPEI_ox probe, selective DOPA recognition is realized with a limit of detection of 1.3 nM. In addition, the proposed hPEI_ox probe is capable to evaluate DOPA in urine, cerebrospinal fluid, and Mucuna pruriens samples. Moreover, the reaction kinetics of DOPA generation and consumption processes can be monitored with hPEI_ox probe. Furthermore, the hPEI_ox probe is capable to evaluate the DOPA decarboxylase activity.