Detection of KRAS G12D point mutation level by anchor-like DNA electrochemical biosensor.

KRAS G12D point mutation plays an important role in the incidence of non-small-cell lung cancer (NSCLC) as well as colorectal cancer, pancreatic cancer and breast cancer. Here, we developed a novel anchor-like DNA (alDNA) electrochemical sensor for the detection of KRAS point mutation level (the concentration ratio of the specific KRAS point mutant DNA (M-DNA) to the total DNA (t-DNA) of both mutant and wild-type DNAs carrying the same allele). Compared to those conventional ligation-based DNA sensors, the proposed alDNA sensor achieved the one-step capture of both wild-type and mutant DNA, and the subsequent detection on one chip, which effectively decreased systematic errors from the uncertain differences on the interfacial structural and microenvironmental changes, improved the detection accuracy. Also, with the usage of formamide-NaCl solution, the whole detection process including the denaturation of double-stranded DNA was performed under mild temperature conditions (~40 °C). It greatly decreased the cost and improved the reproducibility and feasibility of the method. Based on it, the linear correlations with the logarithm of concentration in wide range from 0.1 pM to 10 nM for t-DNA and from 100 pM to 10 nM for M-DNA were achieved, respectively. The analysis of t-DNA- and M-DNA-spiked human serum samples revealed the high accuracy of the method. This alDNA sensor is convenient, low-cost and time-saving, with broad dynamic range, high sensitivity and selectivity. It can meet the demands of the clinical detection on the KRAS point mutation level in blood samples, which means significant for the earlier NSCLC diagnosis, individualized treatment, and therapeutic efficacy evaluation.