Molecularly imprinted polymers enhanced peroxidase-like activity of AuNPs for determination of glutathione

An elaborate composite of molecularly imprinted polymer (MIP)-modified gold nanoparticles (AuNPs)@silica dioxide (SiO₂) was designed and prepared for real-time colorimetric determination of glutathione (GSH) in serum. Firstly, the MIPs were synthesized on the surface of SiO₂ utilizing GSH as template molecules. Then, AuNPs were synthesized on the surface of MIPs@SiO₂ to produce a composite of MIPs modified by AuNPs@SiO₂. Compared with plain AuNPs, the composite possessed better peroxidase catalysis activity due to stabilization and protection from hydrophilic SiO₂, which can catalyze H₂O₂ to·OH oxidizing 3,3,5,5-tetramethylbenzidine (TMB) to the colored product. In addition, its selectivity was enhanced by MIP modification with special recognition cavities. With the composite as the sensor, GSH was precisely and sensitively detected in the range 5 ~ 40 μM with a limit of determination of 1.16 μM according to the principle of inhibitive peroxidase catalysis activity by GSH. The proposed colorimetric detection was successfully utilized for selective, convenient, and rapid determination of GSH in serum. It provided a new strategy for drug real-time monitoring and has high potential in clinical drug analysis.