High-performance electrochemical detection for trace minocycline based on boron-doped-diamond/carbon nanowalls biosensor

Highly sensitive electrochemical detection of trace minocycline (MCL), one of the most important antibiotics, presents a challenge due to the lack of suitable substrates and low detection efficiency. In this work, an electrochemical biosensor with an electrode consisting of boron-doped diamond (BDD) and carbon nanowalls (CNWs) (named BDD/CNWs) is designed for the detection of MCL. The electrochemical behavior of MCL at varying scan rates suggests an adsorption-controlled mechanism dominating the process on the BDD/CNWs electrode. The sensor demonstrates good linearity in the range from 0.02 to 100 μM and achieved a limit of detection as low as 9.8 nM, ascribed to the synergistic effect of the combination of BDD with CNWs, which provide a broad potential window (2.63 V), more reaction sites, and low charge transfer resistance (87 Ω) from the electrode. Examinations of trace MCL in citric acid-phosphate buffer, tap water, rat blood, as well as interference tests, reveal high sensitivity, specificity, stability, and repeatability of the BDD/CNWs electrode, which shows promise for practical applications.