Dual-Modal Lateral Flow Test Strip Assisted by Near-Infrared-Powered Nanomotors for Direct Quantitative Detection of Circulating MicroRNA Biomarkers from Serum.

Quantification of microRNA (miRNA) has attracted intense interest owing to its importance as a biomarker for the early diagnosis of multiple diseases. However, the inefficient capture of microRNAs from complex biological samples due to the passive diffusion of detection probes essentially restricts their accurate quantification. Herein, we report near-infrared (NIR)-powered Janus nanomotors composed of Au nanorods and periodic mesoporous organo-silica microspheres (AuNR/PMO JNMs) as "swimming probes" to assist a lateral flow test strip (LFTS) for direct, amplification-free, and quantitative miRNA-21 detection in serum and cell medium. The AuNR/PMO JNMs were conjugated with designed hDNA as a recognition probe for miRNA-21. Under NIR irradiation, the exposed AuNRs can generate asymmetric thermal gradients around the JNMs to achieve vigorous self-propelled thermophoretic motion. The active movement significantly accelerated the recognition of miRNA-21 targets, which greatly improved the capture efficiency from 59.39 to 86.12% in the reaction buffer. The enhanced miRNA-21 capture enabled direct quantitative miRNA-21 detection on the LFTS assay with both visual and thermal signals. Under the assistance of AuNR/PMO JNMs, a limit-of-detection of 18 fmol/L for miRNA-21 was achieved, which was 12.22-fold compared to that of LFTS assay with static probes. The constructed LFTS assay was further successfully deployed to directly sense the miRNA-21 in spiked serum samples and MDA-MB-231 medium. Overall, the AuNR/PMO JNM-assisted LFTS system unveils a concrete point-of-care testing strategy for precise miRNA detection in real biological samples, which holds great potential for early diagnosis and treatment of miRNA-related diseases.