Screening and diagnosis of colorectal cancer using nucleic acid aptamers targeting Solobacterium moorei: Development of electrochemical sensors for clinical application

Colorectal cancer (CRC) represents a significant global health issue, necessitating innovative approaches for early screening and diagnosis. Recent advances in molecular diagnostics have highlighted the potential of aptamers for use as highly specific and sensitive probes for detecting cancer biomarkers. In this study, we focus on the identification of aptamers that selectively bind to Solobacterium moorei (S. moorei) , a bacterium associated with CRC. By integrating these aptamers into electrochemical sensor platforms, a reliable diagnostic tool is created for facile implementation in the clinical setting. More specifically, nucleic acid aptamers for S. moorei were obtained through whole-cell SELEX, and the affinity and specificity of these aptamers were validated. Subsequently, two types of electrochemical sensors were developed. Firstly, an electrochemical impedance spectroscopy sensor was developed to detect impedance changes on the electrode surface, which were caused by the binding of S. moorei to the aptamer. Secondly, a CRISPR/Cas12a-based electrochemical aptasensor was developed based on the ability of the Cas12a enzyme to be activated by specific single-stranded DNA, triggering its trans-cleavage activity. The limits of detection of these sensors for S. moorei were 30 and 6 CFU/mL, respectively. Clinical validation was performed using patient samples to assess the sensor efficacy in a real-world setting. The obtained results suggested that the abundance of S. moorei in the feces of CRC patients was significantly greater compared to that of healthy individuals. This integration of S. moorei aptamers into electrochemical sensors offers a non-invasive and cost-effective alternative to current screening methods available for CRC.