Preparation and characterization of carboxyl functional mesoporous ZnO-SiO2 composites and in vitro sensing of glucose and vancomycin

Abstract

Here, carboxyl functional mesoporous ZnO-SiO2/poly(methyl methacrylate-methacrylic acid) composite polymer particles, named as ZnO-SiO2/P(MMA-MAA), with different inorganic core against copolymer (w/w) ratios are prepared by a two-step reaction protocol and electrochemically evaluated their suitability for in vitro sensing of glucose and vancomycin (VC). Firstly, simple hydrothermal method is used to synthesize ZnO-SiO2 composite core particles and secondly, carboxyl functional composite polymers are prepared via seeded copolymerization. Before the seeded copolymerization, one part of prepared ZnO-SiO2 composite core particles is calcined (450 °C) for 1 h to generate porosity. The ultimate composite polymer particles with core/copolymer weight ratios of 1/0.7 and 1/1 are named as Non-cal:ZnO-SiO2/P(MMA-MAA)−1, Non-cal:ZnO-SiO2/P(MMA-MAA)−2, Cal:ZnO-SiO2/P(MMA-MAA)−1 and Cal:ZnO-SiO2/P(MMA-MAA)−2, respectively. The glucose oxidase (GOD) immobilized Cal:ZnO-SiO2/P(MMA-MAA)−2/Pt electrode exhibited the best glucose-sensing ability. This particular biosensor possessed a sensitivity of 13.77 µAcm−2 mM−1 alongside a detection threshold of 0.43 µM and 89.2% current response retention after 1100 cycles. The Michaelis-Menten constant (Km) is very low (0.031 mM) as well. The Cal:ZnO-SiO2/P(MMA-MAA)−2 modified Pt electrode is further tested for the in vitro sensing of VC. Overall analyses indicated that the Cal:ZnO-SiO2/P(MMA-MAA)−2 composite polymer can be beneficial for in vitro sensing of both glucose and VC.