LAUSR

Epigenetic alterations hold great promise as biomarkers for early-stage cancer diagnosis. Nevertheless, direct identification of rare methylated DNA in the genome remains challenging. Here we report an ultrasensitive framework nucleic acid-based electrochemical sensor for quantitative and highly selective analysis of DNA methylation. Notably, we can detect 160 fg of methylated DNA in the presence of a million-fold excess of unmethylated DNA samples using this electrochemical methylation-specific polymerase chain reaction (E-MSP) method. The high sensitivity of E-MSP enables one-step detection of low-abundance methylation at two different genes in patient serum samples. By using a combination test with two methylation alterations, we acquire high accuracy and sensitivity for reliable differentiation of prostate cancer and benign prostate hypertrophy (BPH). This new method sheds new light on translational use in early cancer diagnosis, and monitoring patients' responses to therapeutic agents.