Site-specific cleavage-based chemiluminescent optical fiber biosensor for highly sensitive assay of myeloperoxidase activity and inhibitor screening

Nucleic acid site-specific cleavage (NSC) has been an attractive theme for detecting various disease markers. In this study, for the first time, we introduce NSC as the recognition mechanism for developing chemiluminescent optical fiber biosensor (CFOS). The NSC-CFOS is constructed by modifying the hairpin probe containing phosphorothioate site on the surface of an optical fiber, which acts as a specific cleavage site to recognize HOCl catalyzed by myeloperoxidase (MPO). An isothermal enzyme-free hybridization chain reaction amplification is introduced to the proposed NSC-CFOS, which can significantly improve the detection sensitivity. With the MPO-induced NSC as the sensing model, the sensor is employed for the ultrasensitive detection of circulating MPO activity and inhibitors screening. An extremely low detection limit of 0.0017 mU/mL and a wide detection range of 0.005–1 mU/mL have been achieved for MPO detection. Our study shows that combining the site-specific recognition-based sensing mechanism to the optical fiber sensor provides a very promising approach for the point-of-care testing of disease markers in biological samples.