Highly sensitive cholesterol biosensor based on electron mediator thionine and cubic-shaped Cu2O nanomaterials

• Published in: Microchemical journal 2023-02, Vol.185, p.108201, Article 108201
• Main Authors: Yan, Qinghua, Wu, Ruixue, Chen, Hongli, Wang, Haijiao, Nan, Wenbin
• Format: Article
• Language: English
• Subjects: Biosensor; Cholesterol; Cholesterol oxidase; Cuprous oxide; Thionine electrochemical
• ISSN: 0026-265X; 1095-9149
• DOI: 10.1016/j.microc.2022.108201

[Display omitted] •A cholesterol biosensor is prepared based on Cu2O NPs, TH, and ChOx-CS modified electrodes using cubic-shaped Cu2O NPs for the first time.•A high-sensitivity (70.22 µA µM−1 cm−2) cholesterol biosensor, with a wide detection range (10–1000 µM) and low LOD (0.0018 nM) was successfully prepared. The obtained Km low value of 25.359 μM indicated the enhanced affinity of immobilized cholesterol oxidase towards cholesterol and high enzyme kinetics at electrode surface.•Real application analysis demonstrated the present biosensor can be extended for use in clinical testing and food quality control. The preparation of an electrochemical biosensor applicable for the highly sensitive detection of cholesterol content in biological samples in clinical practice is studied in this paper. Commonly used in biosensors, nano-cuprous oxide (Cu2O) contains active electron-hole pairs and a large specific surface area, while thionine (TH) improves the efficiency of electron transfer between the enzyme and the electrode. In this study, a cholesterol biosensor, cholesterol oxidase (ChOx)/thionine/nano-cuprous oxide/ glassy carbon electrode (GCE) (ChOx/TH/Cu2O/GCE), is prepared using cubic-shaped Cu2O as the nanomaterial, TH as an electron mediator, and chitosan (CS) as a cross-linking agent to immobilize cholesterol oxidase. The results show that Cu2O nanoparticles (NPs) are successfully synthesized, and the cholesterol biosensor prepared from synthesized Cu2O NPs exhibits excellent electrochemical characteristics, good linearity (R2 = 0.997) over a substrate concentration range of 10 to 1000 µM, a sensitivity of 70.22 µA µM−1 cm−2, and a low detection limit of 0.0018 µM for the substrate. The ChOx, which immobilizes on the composite electrode, shows a strong affinity for cholesterol due to its low Michaelis–Menten constant (Km) value (25.359 µM). Moreover, with strong anti-interference, good reproducibility, and stability, the cholesterol biosensor can achieve a recovery rate of 99.71 % to 107.75 % according to a recovery test of actual spiked samples. Thus, the prepared nanomaterial-based cholesterol biosensor can be applied to the highly sensitive detection of cholesterol in actual biological samples.