BSA-Assisted Synthesis of Au Nanoclusters/MnO2 Nanosheets for Fluorescence "Switch-On" Detection of Alkaline Phosphatase.

A fluorescence probe for "switch-on" detection of alkaline phosphatase (ALP) was developed based on Au nanoclusters anchored MnO₂ nanosheets (Au NCs-MnO₂ NSs), which were synthesized using bovine serum albumin (BSA) as template through a simple one-pot approach. In the sensing system, MnO₂ NSs function as both energy acceptors and target identifiers, effectively quenches the fluorescence of Au NCs via fluorescence resonance energy transfer (FRET). The presence of ALP catalyzes the hydrolysis of L-ascorbic acid-2-phosphate (AAP) to ascorbic acid (AA), reducing MnO₂ NSs to Mn²⁺ and facilitate the fluorescence recovery of Au NCs. The fluorescence assay offers the advantages of facile preparation, cost-effectiveness, good specificity, and high sensitivity. Moreover, the assay exhibits a broad linear range (0.005 U/mL to 8 U/mL) for ALP detection with a remarkable limit of detection of 0.0015 U/mL. Notably, this assay demonstrates promising applicability for detection ALP in human serum samples, thereby providing valuable potential for clinical applications.