A novel dsDNA decamer-based electrochemical biosensor for selective determination of irinotecan active metabolite-SN38

This paper presents a novel biosensor for detecting the active metabolite of irinotecan, SN38, with high selectivity and sensitivity. The biosensor utilizes a dsDNA decamer (5 '-GCGTTGTCGC-3 ') that selectively interacts with SN38. The biosensor, consisting of a screen-printed graphite electrode with the dsDNA decamer as the recognition layer, demonstrates stability, sensitivity, and selectivity towards SN38 through electrochemical studies. It offers a wide linear range of 1-200 nM, comparable to the high-performance liquid chromatography (HPLC) method, with a sensitivity of 57 nA/nM and a detection limit of 1.06 nM. Compared to a bare graphite electrode, the biosensor exhibits a significant 31-fold increase in sensitivity and a detection limit three orders of magnitude lower. Selectivity studies were conducted using electrochemically active and inactive interferents, including biologically active compounds. Bioreceptor interactions with chosen interferents were examined using HPLC and nuclear magnetic resonance (NMR). Tests of the biosensor was performed using laboratory samples and artificial urine samples spiked with SN38. This disposable biosensor, based on dsDNA, provides an innovative approach for accurately determining SN38 levels in the therapeutic drug concentration range. It holds promise as an alternative method for clinical diagnosis and monitoring of SN38 levels in cancer patients undergoing irinotecan treatment.