Construction of Co@C Hybrid Nanostructure: Electrochemical Biosensor for Detection of Penicillin Sodium in Milk

Abstract

In this study, a cobalt-based mesoporous carbon material (Co@C) was prepared by self-assembly method and impregnation method, and carboxyl functionalization was carried out to obtain COOH-Co@C. Then, the penicillinase (Pen X) was immobilized on the carrier material by covalent binding. The methylene blue was electropolymerized onto the glassy carbon electrode, and then the immobilized enzyme material was modified onto the modified electrode to prepare a biosensor. After optimization of experimental conditions, the differential pulse method was used to detect penicillin sodium (Pen G) as an antibiotic model. Notably, measurement was performed without any pH redox probe, and a low limit of detection was obtained. The results showed that when the concentration of Pen G was 0.1–10 ng mL−1, the corresponding current and concentration of the sensor showed a good linear relationship. The linear equation is y = 0.3881x + 17.20 (r2 = 0.9974); when the concentration range is 10–100 ng mL−1, the linear equation is y = 0.1170x + 19.73 (r2 = 0.9959). The limit of detection is 0.64 ng mL−1. The sensor is not only simple to prepare but also has high sensitivity and accurate detection. Finally, using the spike method, the actual sample detection was successfully realized.