An innovative PCR-free approach for DNA methylation measure: An application for early colorectal cancer detection by means of an organic biosensor

Colorectal cancer (CRC) is one of the most treatable cancers, but high mortality levels have been reported as a result of its asymptomatic nature in the very early stages of the disease. This justifies the importance of mass screening programs to fight colorectal cancer, and thus the interest in the development of minimally invasive, cost-effective tests. In this paper, a novel approach for the detection of CRC biomarkers in DNA stool samples is reported. The strategy is based on the detection of DNA methylation alterations as highly sensitive and selective epigenetic biomarkers by means of an organic transistor-based sensor, particularly suited for the integration in portable, low-cost and easy-to-use sensing system. A clear demonstration of the detection strategy effectiveness is provided using a standard CRC biomarker, namely SEPT9 (encoding for septin9), and further deepened using an innovative biomarker, GRIA4 (encoding for glutamate ionotropic receptor AMPA type subunit 4), in several samples coming from CRC patients. The correct detection of biomarkers, as confirmed by independent optical analysis, is demonstrated both on amplicons and unamplified genomic DNA derived from stool samples, thus making the proposed approach particularly attractive for the future development of non-invasive, PCR-free and low-cost mass screening tests.