Ultrasensitive and label-free detection of piR-54265 biomarker by solution-gated graphene transistors with poly-adenine DNA assembled probe for accurate diagnosis of colorectal cancer

Colorectal cancer (CRC) is one of the malignant tumors with high morbidity and mortality rates worldwide. Conventional screening methods, such as endoscopy and fecal testing, are invasive and have low compliance, highlighting the urgent need for efficient, non-invasive diagnostics. Circulating small RNAs, including the sequence annotated as PIWI-interacting RNA-54265 (piR-54265), have been reported to be closely associated with CRC and represent promising serum biomarkers in liquid biopsy research. This study aims to develop an ultrasensitive, label-free solution-gated graphene transistor (SGGT) based biosensor to detect piR-54265 in serum samples, addressing limitations of current CRC biomarker detection. The Polyadenine 15 -thymine 5 (PolyA 15 T 5 -DNA) probe was designed with an L-shaped configuration, constructing a sensing interface. This configuration is proposed to facilitate a favorable probe conformation for nucleic acid recognition at the gate interface, thereby contributing to the overall sensing performance of the biosensor. The biosensor achieves a remarkable limit of detection (LOD) of 8.56 × 10 −19  M, with a linear detection range from 1 aM to 10 nM, and excellent selectivity for piR-54265. Clinical serum samples analyzed under diluted conditions demonstrate clear differentiation between CRC patients and non-cancer controls, with receiver operating characteristic (ROC) analysis further confirming its exceptional diagnostic performance and achieving an area under the curve (AUC) of 1.0. These results establish a SGGT-based sensing platform for CRC-associated RNA detection and highlight its potential for non-invasive biomarker detection and future diagnostic applications.