A microdroplet SERS-RCA biosensor with enhanced specificity and reproducibility for profiling dual miRNAs in idiopathic pulmonary fibrosis diagnosis and monitoring

Accurate detection of low-abundance, highly homologous miRNAs is crucial for the precise diagnosis and monitoring of idiopathic pulmonary fibrosis (IPF). In this study, a fully integrated microdroplet analysis platform based on rolling circle amplification (RCA) technology and surface-enhanced Raman spectroscopy (SERS) has been developed to precisely detect miRNA-21 and miRNA-155 in the serum of IPF patients. By utilizing the RCA strategy, the constructed sensor is able to realize single nucleotide variation detection with prominent specificity. The integration of microfluidics provides satisfactory directions to the reproducibility issue in SERS, thereby improving detecting sensitivity. With this sophisticated biosensing platform, low detection limits of 0.398 fM and 0.215 fM have been achieved for miRNA-21 and miRNA-155, respectively. Moreover, the combined determination of these two miRNAs demonstrates a more substantial diagnostic potential, with an AUC value of 0.884, higher than their evaluations. When used in conjunction with high-resolution chest computed tomography, this innovative SERS-RCA microfluidic biosensor can serve as an auxiliary diagnostic tool for IPF risk assessment, particularly for real-time monitoring of miRNA levels in patients undergoing chemotherapy. This sensing technique holds promise to extend into versatile platforms for diverse miRNA detection in the rapid and accurate diagnosis of various diseases beyond IPF.