Development of a QCM-based biosensor for the detection of non-small cell lung cancer biomarkers in liquid biopsies

Lung cancer is the main malignant cancer reported worldwide, with one of the lowest survival rates. Deletions in the Epidermal Growth Factor Receptor (EGFR) gene are often associated with non-small cell lung cancer (NSCLC), a common subtype of lung cancer. The detection of such mutations provides key information for the diagnosis and treatment of the disease; therefore, the early screening of such biomarkers is of vital importance. The need for fast, reliable, and early detection means applied to NSCLC has led to the development of highly sensitive devices that can detect cancer-associated mutations. Such devices, known as biosensors, are a promising alternative to more conventional detection methods and can potentially alter the way cancer is diagnosed and treated. In this study, we report the development of a DNA-based biosensor, namely a quartz crystal microbalance (QCM), applied to the detection of NSCLC, from liquid biopsies samples. The detection, as is the case of most DNA biosensors, is based on the hybridization between the NSCLC-specific probe and the sample DNA (containing specific mutations associated with NSCLC). The surface functionalization was performed with a blocking agent (dithiothreitol) and thiolated-ssDNA strands. The biosensor was able to detect specific DNA sequences in both synthetic and real samples. Aspects such as reutilization and regeneration of the QCM electrode were also studied.