Terahertz Let-7a specific sensing and DNA differentiation enabled by Q-BIC metasurface and phenylboronic acid-gold nanoprobe.

Nucleic acids are genetic molecules that carry biological information, the development of accurate nucleic acid detection technology is of great significance for the treatment of some diseases. Here, we proposed a novel scheme to specific detect Let-7a (miRNA) and simultaneous discrimination from DNA based on terahertz (THz) metasurface. The metasurface is designed for supporting quasi-bound states in continuum (Q-BIC) resonance, which can effectively improve the sensing performance. Numerical simulation consistent with experimental results confirms the Q-BIC is induced by the symmetry broken between the metal wires. To specific detect trace amount Let-7a, the PBA-AuNPs probe developed by modifying Au nanoparticles (AuNPs) with phenylboronic acid (PBA), is integrated into metasurface for signal amplification. Our results show that highly sensitive and selective detection of Let-7a is achieved, the detection limit can reach to 0.01 nM. More importantly, due to the selective binding of the nanoprobe, the sensitivity for Let-7a is more than 3 times that of DNA sharing the same sequence. Even in serum samples, the frequency shift of resonance still maintains a good linear relationship with the logarithm of the Let-7a concentration. This miRNA-targeted PBA-AuNPs amplification technology offers a versatile platform with translational potential across disciplines, particularly advancing emerging THz metasurface-based biosensing.