Enhancing early breast cancer detection with APE1-triggered oligonucleotide probes and graphene oxide: The impact of variable AP site modification on sensitivity and specificity.

There is a critical need for inclusive diagnostic platforms to enhance the accuracy of early breast cancer detection. Dysregulated microRNA-1246 (miR-1246), closely linked to the disease progression and recurrence, has emerged as a promising diagnostic and prognostic biomarker for BC. However, achieving simple, rapid, and ultrasensitive quantification of serum miRNAs remains significant challenge. In this study, we present an innovative detection platform triggered by endogenous DNA repair enzyme apurinic/apyrimidinic endonuclease 1 (APE1). This platform utilizes an oligonucleotide probe with variable modified AP sites (denoted as AOP) coupled with graphene oxide (GO) for quantifying miR-1246. Our in vitro experiments reveal that the proposed method employing the AOP2 probe with two AP sites exhibits exceptional selectivity and sensitivity. The method achieves a detection limit as low as 2.3 pM towards miR-1246, which is approximately 260-fold more sensitive than the enzyme-free system. RT-qPCR experiments further validate the accuracy and practicability of the AOP2-based platform. In clinical trials, our platform has successfully differentiated between BC patients and normal healthy controls. In conclusion, we have established an integrated biosensing technology for PCR-free, non-invasive liquid biopsies of miR-1246, offering a promising approach for BC diagnosis.