Ligand-engineering multienzyme activity of metal-organic frameworks confined Au for multiple target biosensing.

In this research, a surface ligand engineering strategy is employed to fabricate UiO-66 confined Au nanoclusters (UiO-66@Au) with controllable multienzyme performances. Especially, ligand PSS and PVP can trigger optimized peroxidase (POD) and glucose oxidase (GOx) mimic activity respectively. Mechanistic studies revealed that electron transferring between Au and ligands can be an effective tactic to regulate the multienzyme activity. Theoretical calculations revealed that electron-withdrawing polystyrene sulfonate (PSS) can decrease the key energy barriers of ·OH desorption in POD process and electron-donating polyvinylpyrrolidone (PVP) decreased the key energy barriers of O2 to OOH∗ in GOx catalysis, which confirmed the enhanced POD and GOx activity correspondingly. For practical application, PSS-UiO-66@Au coupled lateral flow assay (LFA) can visually detect HER2-positive breast cancer exosomes as low as 428 exosomes/μL, about 16355-fold higher sensitivity than that of common LFA. PVP-UiO-66@Au with superior GOx-mimic activity can detect salivary glucose as low as 19 μM, meanwhile, due to the effective gluconic acid adsorption repulsion by PVP, PVP-UiO-66@Au displays superior stability even after 10 reuse cycles This work provides a simple route to regulate the multi-enzyme properties of UiO-66@Au and broadens the application in multiple target biosensing.