Smartphone-Assisted Point of Care Testing for Colorectal Cancer Screening: Application of Split Light-Up Aptamer for DNA Methylation Detection

Aberrant DNA methylation plays a crucial role in carcinogenesis and serves as a valuable biomarker for the early detection of colorectal cancer. However, most current DNA methylation detection methods still rely on fluorescent probes labeled with both a fluorophore and a quencher, which are costly and require time-consuming synthesis procedures. Therefore, there is an urgent need for convenient, visual, and rapid diagnostic platforms utilizing label-free probes for DNA methylation analysis. Herein, we present a low-cost and portable smartphone-based point-of-care testing (POCT) platform for rapid and visual detection of DNA methylation by utilizing split light-up DNA aptamers as label-free signal transducers in conjunction with the assistance smartphone camera. Compared to conventional fluorescent probes, the split light-up aptamers offer simplified synthesis and eliminate the need for labeling. Based on the RGB values of the images, a linear relationship was established between fluorescence intensity and the logarithm of DNA methylation concentration over the range of 10 to 5000 nM, with a detection limit of 0.769 nM. Furthermore, the platform performed well in real samples within 20 min. We believe that the POCT platform has great potential for biomedical applications and public health surveillance in the face of emerging infectious diseases.