Bioinspired Copolymers Based Nose/Tongue-Mimic Chemosensor for Label-Free Fluorescent Pattern Discrimination of Metal Ions in Biofluids

There is a close correlation between body health and the level of biofluid-derived metal ions, which makes it an attractive model analyte for noninvasive health monitoring. The present work has developed a novel nose/tongue-mimic chemosensor array based on bioinspired polydopamine/polyethylenimine copolymers (PDA/PEI_n) for label-free fluorescent determination of metal ions in biofluids. Three types of PDA/PEI_n (PDA/PEI₆, PDA/PEI₁₈, and PDA/PEI₄₈) were prepared by using different concentrations of PEI to construct the proposed sensor array, which would lead to unique fluorescence response patterns upon challenged with metal ions for their pattern discrimination. The results show that as few as 3 PDA/PEI_n sensors can successfully realize the largescale sensitive detection of metal ions in biofluids. Moreover, we have demonstrated that PDA/PEI_n sensors are qualified for lifetime-based pattern discrimination application. Furthermore, the sensors can distinguish between different concentrations of metal ions, as well as a mixture of different metal ions in biofluids, even the mixtures with different valence states. The method promises the simple, rapid, sensitive, and powerful discrimination of metal ions in accessible biofluids, showing the potential applications in the diagnosis of metal ion-involved diseases.