A lateral flow strip biosensor platform based on cascade nucleic acid amplification technology for ultrasensitive detection of OSCC-associated salivary MicroRNA

Oral squamous cell carcinoma (OSCC) is the well-known malignancy and poses a serious threat to human health with high morbidity and mortality. Early detection and treatment can improve the recovery rate and reduce complications of OSCC. Therefore, we designed a lateral flow strip biosensor platform (HRCA-strip) based on the cascade nucleic acid amplification technology (HRCA) for colorimetric analysis of OSCC-associated has-microRNA 31-5p (miRNA 31). In this work, the target miRNA 31 mediated the formation of the sandwich complex structure on the surface of magnetic beads (MBs). Then, the sandwich complex structure could activate cascade amplification reaction between hybridization chain reaction (HCR) and rolling-circle amplification (RCA) to generate numerous G-quadruplex structures. The G-quadruplex structures combined with hemin to form hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme (H/G-HRP mimic enzyme) which were enriched on the T-line and catalyzed the oxidation of chromogenic substrates to generate colorimetric signal on the strip. The HRCA-strip platform could achieve highly sensitive and specific miRNA 31 detection with the limit of detection (LOD) as low as 3.21 fM. Moreover, the designed HRCA-strip platform also enabled portable detection of miRNA 31 in clinical sample which might show good potential for early clinical diagnosis of OSCC.