Advancing the\nValidation of the Enrichment-Enhanced\nDetection Strategy with Au Nanoclusters for AChE Detection

High-sensitivity\nfluorescent probes provide a powerful tool for\nunderstanding life processes and functioning mechanisms. Therefore,\nthe development of a universal strategy to optimize probes holds substantial\nimportance. Herein, we developed a novel strategy for common probe\nupgrades: rather than simply pursuing a higher fluorescence intensity\nof the probe itself, we tried to promote the detection sensitivity\nby enhancing the probe–substrate interactions. Fortified with\npolyionic polymers, self-assembled probes could be endowed with enhanced\nattractions to the substrate. In this work, we took the AChE-AuNCs\ndetection system as a typical and important example to verify this\nconcept of the “enrichment-enhanced detection” strategy\n(EED strategy). Two probes, AuNCs@GC and AuNCs@CMCS, with similar\ncomposing polymers (chitosan derivatives), microstructures, fluorescence\nprofiles, and distinct charges were delicately designed and thoroughly\nstudied. CMCS with an abundance of negatively charged carboxy groups\nplays an important role in the enrichment of thiocholine through electrostatic\ninteractions. Thus, despite having similar composing components, structures,\nand almost identical fluorescence profiles, the negatively charged\ncomposite shows superior sensitivity (15.2-fold enhancement) and response\ntime (2-fold faster) compared to the AuNCs@GC, thereby validating\nthe feasibility of the EED strategy. Overall, our work validates the\nEED strategy and applies it to the accurate detection of AChE activity.\nWe believe that this strategy offers substantial insights for the\ngeneralization and enhancement of advanced nanoprobes.