Vibrational Alchemy of DNA: Exploring the Mysteries of Hybridization under Cooperative Strong Coupling with Water

Vibrational strong coupling (VSC) as an emerging technology can modify molecular reactivities. Previously, we found that VSC can drive deoxyribonucleic acid (DNA) coassembly in the dark; however, the underlying mechanism still lacks sufficient exploration. Here, we take the melting temperature (Tm) as a measure to systematically study how VSC affects DNA hybridization in the optical resonator. The results indicate a strong correlation between Tm and coupling strength; i.e., VSC with O–H stretching vibration can significantly reduce Tm and favor nonspecific hybridization of DNA molecules. The mechanism is ascribed to the cooperative VSC between water and base pairs, since the number of hydrogen bonds is much higher in solvent water than in DNA molecules. More interestingly, concentrations of Mg2+ also play key roles in changing Tm due to the alteration of the hydrogen-bond network. The hybridization landscape of DNA molecules is significantly reduced due to the increased active energy contributed by Rabi splitting, which is proven by fluorescence quenching-based Tm measurement. Gel electrophoresis further demonstrates that VSC can induce DNA to form unstable nanoassemblies. This work sheds light on how the reactant-solvent cooperative VSC regulates bioreactions, which is expected to find wide applications in the biomedicine field.