An electrochemical sensor based on immobilized cystathionine β-synthase (CBS) enzymes and Pd@CuO modified covalent organic framework for specific detection of homocysteine

Background Homocysteine (Hcy) has been recognized as an independent risk factor for the development of cardiovascular disease. Many electrochemical detection methods have been developed for analyzing Hcy, however, the specificity of these methods is based on the interaction between the sulfhydryl groups in Hcy and the metallic materials, and thus the specificity of such detection is not satisfactory. Results In this study, an electrochemical sensor based on COFs and Pd@CuO was developed for the specific detection of Hcy. Firstly, COFs material was used as an immobilized carrier for cystathionine β-synthase (CBS), and the immobilized CBS as a recognition unit was able to catalyze the production of H 2 S from the substrates (Hcy and Cys) in a specific manner. Secondly, the Pd@CuO composite material has excellent conductivity and can catalyze H 2 S as a source of electrochemical signal generation. The electrochemical sensor constructed based on the above principles has a good electrochemical response to Hcy within the range of 5 μM to 100 μM, and the limit of detection can reach 0.11 μM (S/N = 3). In addition, the constructed sensor has good reproducibility, stability and specificity, and has good recoveries in the detection of real plasma samples, which provides a potential application for the diagnosis of homocysteinemia. Significance and Novelty The electrochemical sensor significantly increases the specificity of detection by utilizing immobilized Hcy specific catalytic enzymes CBS. In addition, Pd modified CuO@COFs electrode greatly increases the conductivity of the electrode, thereby increasing the sensitivity of detection. These characteristics make the electrochemical sensor have good application prospects for detecting the Hcy in clinic in the future.