Sensitive microRNA detection based on bimetallic label photothermal lateral flow locked nucleic acid biosensor with smartphone readout

Fast, convenient, and highly sensitive detection of microRNA (miRNA) is vital for the early diagnosis of diseases. Lateral flow biosensor (LFB) as microdevice has been used in rapid detection, however, the sensitivity is not satisfied for low-abundant miRNA detection, and short length of the miRNA requires high affinity detection probe. To address these issues, herein, we synthesized palladium-gold (Pd-Au) bimetallic nanoplates with high photothermal effect combined locked nucleic acid (LNA) detection probe to develop a photothermal lateral flow locked nucleic acid biosensor (P-LFLNAB) for miRNA detection. The P-LFLNAB enables sensitive and selective miRNA-21 detection with detection limit down to 0.094 pM using a smartphone with external thermal imager, which is 639.5 times lower than that of the conventional gold nanoparticles based colorimetric LFB and the most sensitive enzyme-free LFB for miRNA detection. Besides, the P-LFLNAB achieved single-base mismatch discrimination and can quantify signals in various cell lysates. This highly sensitive, selective and portable P-LFLNAB with smartphone readout has great potential in point-of-care test of miRNAs-related biomedical application.