Early-onset colorectal cancer detection through a non-invasive label-free electrochemical immunosensor probe

Early-onset colorectal cancer (CRC; <50 years) is rapidly increasing in the United States and disproportionately affects Hispanic and African American patients. Since survival rates are positively associated with early detection, the absence of reliable and accessible screening tools for younger adults remains a significant unmet need. Liquid-biopsy diagnostics offer a practical alternative to invasive tests; however, the risk of false negatives is too high. Using gene-expression datasets, cDNA arrays, tissue-microarrays, and tissues from CRC patients, we have identified and validated the elevated expressions of CCNB1 and MCM10, at the transcript and protein levels, in Hispanic early-onset CRC patients when compared to their Non-Hispanic White counterparts. We are developing a label-free electrochemical immunosensor for point-of-care (POC) detection of these early-onset CRC biomarkers. As a prototype, we designed a sensor targeting the early CRC biomarker CCSP-2. A gold working electrode (Au) was functionalized with cysteine-modified recombinant Protein G, which selectively binds the Fc region of hIgG to achieve controlled orientation of CCSP-2 antibodies (Ab) on the Au surface. After Ab immobilization, bovine serum albumin (BSA) was used as a blocker, and each modification step was characterized by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). EIS quantified CCSP-2 antigen (Ag) through changes in relative charge-transfer resistance (ΔR ct /R cti ). The resulting calibration curve (ΔR ct /R cti vs Ag) demonstrated strong linearity (R 2 = 0.95) from 10-100 ng/µL, with a detection limit of 0.71 ng/µL. To further enhance stability and antifouling performance in complex biofluids, we are integrating a porous BSA-glutaraldehyde-gold nanowire (BSA-GA-AuNW) hydrogel onto Au interdigitated microelectrodes, followed by antibody immobilization and testing of early-onset CRC biomarkers. This conductive, hydrophilic matrix is expected to improve sensitivity and specificity while enabling reliable blood-based measurements. This non-invasive, low-cost electrochemical probe has strong potential to expand screening and improve early detection of CRC, especially among younger and underserved populations, thereby improving the survival rates.