A novel APE1-assisted cycling amplification for rapid and ultrasensitive SERS detection of TK1 mRNA in human serum

Quantitative mRNA expression levels are essential for differential and clinical diagnoses. In this work, we present an apurinic/apyrimidinic endonuclease 1 (APE1)-assisted SERS sensing platform for rapid and ultrasensitive detection of TK1 mRNA. This platform utilizes a hairpin probe that contains a TK1 mRNA capture sequence along with apurinic/apyrimidinic (AP) sites, which is specifically recognized and cleaved by APE1. Upon introduction of the target mRNA, hybridization occurs between the mRNA and the AP probe (HAP) within the hairpin structure, forming a double-stranded complex. APE1 then cleaves the HAP at the specific AP sites within the double-stranded complex, leading to a measurable change in the SERS intensity of the FAM-labeled HAP. Based on this principle, the developed SERS sensing platform demonstrates a highly linear response for TK1 mRNA detection across a wider range from 1 fM to 10 nM, with a detection limit (LOD) of 0.2 fM. Moreover, the SERS sensing platform shows great potential for the precise and quantitative detection of TK1 mRNA in human serum, which could be instrumental for mRNA-related research and the early clinical diagnosis of diseases.