Surface-enhanced Raman spectroscopy biosensor based on silver nanoparticles@metal-organic frameworks with peroxidase-mimicking activities for ultrasensitive monitoring of blood cholesterol

Abstract

Nanozymes have received much attention due to their advantages of lower cost, higher stability, and simple preparation when compared to conventional enzymes. Herein, we prepared a peroxidase-mimicking nanozyme by the growth of silver nanoparticles (AgNPs) on the surface of a metal-organic framework (MOF) called MIL-101 (Fe), obtaining the AgNPs@MOF. The AgNPs@MOF was applied as surface-enhanced Raman spectroscopy (SERS) substrate and simultaneously served as peroxidase mimics to oxidize the without Raman-active leucomalachite green into the Raman-active malachite green. Based on the excellent peroxidase-mimicking activity and high SERS enhancement of AgNPs@MOF, a highly sensitive and specific SERS sensing platform was proposed to monitor cholesterol. Under the optimized conditions, the established biosensor achieved a broad dynamic detection range of 1.0–100 μM and a relatively low limit of detection down to 0.36 μM. More importantly, this reported sensing platform was employed to detect cholesterol in human serum with excellent accuracy and precision, providing great potential in health management and clinical diagnosis.