SERS Sensor Based on CHA Reaction for EGFR Mutation Typing in Advanced Lung Cancer

With the continuous development of medical technology, especially molecular biology technology, targeted therapy for lung cancer has made rapid progress, and the prognosis of targeted therapy has been significantly improved compared with chemotherapy. In clinical practice, molecular typing of EGFR mutations is conducive to timely and optimal tumor treatment. At present, common detection methods include Sanger sequencing, next-generation sequencing (NGS) and RT-PCR, and most of their samples are from tumor tissues. However, the defects of tissue samples such as small quantity, long detection cycle, heterogeneity and invasiveness have brought challenges to the application of these methods. Therefore, in order to overcome the many limitations faced in detecting gene mutations in tumor tissues, it is of great significance to seek feasible alternatives that are easy to obtain and low intrusiveness for EGFR mutation screening. Previous reports have shown that clinical serum circulating tumor DNA (ctDNA) retains relatively complete genetic information, and EGFR mutations in tumor cells can be reflected in ctDNA in real time. In blood, the detection of ctDNA has unique advantages, such as high timeliness, low false positives and high specificity. Therefore, with blood as an ideal substitute, low-invasive ctDNA detection can become an effective tool for liquid biopsy. Unfortunately, there is no standardized method to detect EGFR mutations in blood samples. Common methods for detecting ctDNA include NGS, mutation amplification retardation system (ARMS) and digital PCR. However, these methods have disadvantages such as complex operation, long time, high cost, low sensitivity and poor specificity. Therefore, a new method for rapid and sensitive ctDNA typing detection is urgently needed.

SERS has become one of the most promising tools in biomedical analysis due to its excellent optical properties. However, since the copy number of mutant ctDNA in blood is only 1% of wild-type DNA, traditional SERS technology cannot meet the strict conditions for ultrasensitive detection. Catalytic hairpin assembly (CHA) is a typical isothermal enzyme-free signal amplification strategy. In order to further improve the analytical ability of the detection platform for low-abundance ctDNA, we combined CHA and SERS as a biosensor constructed as a dual signal amplification strategy to improve the analytical performance of the detection platform for EGFR in serum. In our previous study, we successfully constructed a CHA reaction-mediated self-calibrated SERS biosensor for EGFR mutation typing (Del-19, T790M, L858R) in lung cancer patients, and verified the accuracy, sensitivity, and specificity of the SERS biosensor in a small sample of 32 patients to be over 95%. In order to obtain the highest level of clinical evidence and truly achieve clinical transformation, this prospective, multicenter clinical study aims to verify the analytical efficiency of the SERS biosensor for EGFR mutation typing in advanced lung cancer patients.