Semiconductor technology for early detection of DNA methylation for cancer: From concept to practice

The electrical detection of DNA methylation based biomarkers using semiconductor technology shows great promise for early cancer screening. Presented is the very first proof-of-concept example of using CMOS-based technology for real-time DNA methylation detection using Ion-Sensitive Field-Effect Transistors (ISFETs). An electrochemical label-free approach was applied in two gene assays, each one of which incorporated the sequences of DAPK1 and CDKN2A/p16-INK4 (p16) gene promoters at a both methylated and unmethylated state, performing isothermal methylation-specific amplification and detection both in-tube and on-chip (real-time). Good discrimination was shown between the two states, achieving a very good average pH signal change for the methylated state of 1.91 for DAPK1 assay and of 1.58 for p16 assay in the tube test. The real-time on-chip test showed similarly good real-time differential signal change in favour of methylated DNA, reaching 37 mV for DAPK1 assay and 23 mV for p16 assay, validating the results from the proof-of-concept test of pH-LAMP in-tube while confirming the sensitivity of real-time methylation-specific pH-LAMP on-chip.