Advances in circulating tumor DNA detection from traditional methods to diversified signal amplification biosensing strategies

Circulating tumor DNA (ctDNA), as the core biomarker of liquid biopsy, carries many tumor-specific molecular characteristics and is a key carrier for non-invasive early screening and dynamic monitoring of cancer. However, the low abundance and the interference of ctDNA in peripheral blood have long constrained the development and application. Signal amplification biosensing strategies have become the core technical path to break through the bottleneck of ctDNA detection due to their high sensitivity, rapid response, and miniaturization potential. Based on the technical characteristics of various diversified biosensing schemes, this paper provides a systematic review of four mainstream high-sensitivity amplification systems for ctDNA: intrinsic signal amplification at the nanointerface, isothermal DNA molecular cascade amplification system, CRISPR/Cas specific amplification, and target magnetic pre-enrichment, which categorizes the signal amplification mechanisms, analytical performance, and differences in practical sample applications of each system. This review summarizes current research progress in ctDNA detection technology, providing theoretical support for promoting the clinical implementation of ctDNA detection technology and the construction of a precise diagnosis and treatment system.