SPRi/SERS dual-mode biosensor based on ployA-DNA/ miRNA/AuNPs-enhanced probe sandwich structure for the detection of multiple miRNA biomarkers

MicroRNA (miRNA) has broad application prospects in the early detection of various cancers. In this work, a SPRi/SERS dual-mode biosensor was developed on the same gold chip by AuNPs as the reinforcing medium. High throughput and sensitivity detection of three typical cervical cancer markers miRNA21, miRNA124 and miRNA143 were achieved based on the sandwich structure of polyA blocks-DNA capture probe/target miRNA/AuNPs-assistant probe or SERS nanoprobes. AuNPs greatly improved the SPR response due to mass increase and more sensitive refractive index changes. Meanwhile, due to the LSPR effect of AuNPs, the signal of SERS nanoprobe can be amplified. The miRNAs were detected in serum to verify its practicality. SPRi achieved detection of three miRNAs simultaneously. LODs were 6.3 fM, 5.3 fM and 4.6 fM, respectively, and wide dynamic response range of 500 pM-10 nM. While SERS assay ensured high sensitivity with LODs as low as 1 fM, 0.8 fM and 1.2 fM, respectively, and with the recoveries in the range of 90.0 %-100.2 %. The redundant detection signals of the two modes can provide more reliable data to prevent false positive or false negative detection, and have great application prospects in detection of cancer-related nucleic acids in early stage of disease.