SERS and colorimetric dual-mode detection of cholesterol during drug treatment of atherosclerosis.

Abstract

Foam cell formation caused by cholesterol accumulation in macrophages is an early warning of atherosclerosis. Therefore, in situ and accurate determination of intracellular and extracellular cholesterol in macrophages is of great significance for the early diagnosis of atherosclerosis and the evaluation of its therapeutic effect. Herein, a surface-enhanced Raman spectroscopy (SERS) and colorimetric dual-response plasmonic nano-sensing system was established based on a double-enzyme cascade catalytic reaction to accurately monitor the changes in cholesterol levels during the occurrence and development of atherosclerosis. Cholesterol oxidase modified on gold nanoparticles can catalyze the oxidation of cholesterol to hydrogen peroxide, which oxidizes 3,3,5,5-tetramethylbenzidine (TMB) to oxidation state TMB (oxTMB) under the catalysis of horseradish peroxidase (HRP). The oxTMB showed a very strong SERS signal under the effect of plasmonic enhancement of gold nanoparticles, and the solution of oxTMB is bright blue compared to colorless TMB. Therefore, the dual-response sensing of cholesterol was realized by monitoring SERS and UV absorption signals of the final product oxTMB. Our results suggest that the free cholesterol in macrophages increases after the treatment of avasimibe, which ultimately leads to apoptosis of macrophages. Another drug, high-density lipoprotein, promoted the efflux of intracellular cholesterol and inhibited the foaming of macrophages, thus delaying the development of atherosclerosis. The colorimetric and SERS double-response plasmonic nanosensor realized highly sensitive, specific, and accurate monitoring of intracellular and extracellular cholesterol levels during drug treatment of atherosclerosis. It is expected to provide an effective tool and methodological reference for the prevention and diagnosis of atherosclerosis and a series of cardiovascular diseases related to cholesterol.