Improved SERS Biosensor Constructed by PolyA-Assisted Plasmonic Au Networks and Mg²⁺-Mediated Amplification

Circulating tumor DNA (ctDNA) acts as a vital biomarker for cancer treatment and monitoring. However, its detection is often hindered by the scarcity of concentration; thus, the conversion and amplification of ctDNA and a highly sensitive detection method designed are crucial. PolyA, rich in adenines, selectively binds to Au nanoparticles (Au NPs), which is a potential candidate for the formation of DNA nanonetworks with ordered gaps. In this study, polyA-assisted plasmonic Au (PPA) networks were constructed by combining a Mg²⁺-mediated amplification strategy. By utilizing the surface-enhanced Raman scattering (SERS) technique, a highly sensitive SERS biosensor was fabricated for the detection of ctDNA, with a detection limit of 10.8 fmol/L. This research introduces a robust platform for fabricating precision-engineered PPA networks and represents a significant advancement in SERS analysis. This advancement enables accurate and reliable ctDNA detection in the complex environment of biological fluids, paving the way for more effective cancer monitoring and treatment strategies.