Mid-infrared (MIR) light can effectively regulate the conformation of biological macromolecules such as DNA and proteins. However, the role of MIR light in DNA replication is still unclear. Here, using the polymerase chain reaction (PCR) as a DNA replication model in vitro, we investigated the quantum effect of MIR light (5.6 μm) on DNA replication. We discovered that the vibrational strong coupling between MIR photons and carbonyl groups can significantly affect the denaturation process of PCR by promoting double-stranded DNA (dsDNA) unwinding and ultimately improve the efficiency of PCR. The quantum effect of MIR photons depends on both the irradiation power and the dsDNA length, interestingly, which can be further improved when replacing H 2 O with deuterium oxide (D 2 O), further indicating a nonthermal quantum effect due to the coherent coupling of vibrational DNA molecules. These results provide a new perspective for the roles of MIR photons in biochemical reactions while showing potential biomedical applications of MIR light.
Vibrational strong coupling (VSC) has been an emerging tool to regulate the energy landscape of chemical bonds. VSC can be achieved by tuning the optical mode of Fabry-Peŕot (FP) cavities to resonantly couple with molecular vibrations, which generates new light-molecule hybrid states and energy levels, thereby directly influencing chemical reactions. Herein, VSC with FP cavities can significantly reduce the melting temperature (T m ) of dsDNA, which can be precisely measured using DNA origami coassembly, benefiting from the precise hybridization-dependent origami conformation. An 8.5-μm-spaced FP cavity can strongly couple with the vibration of the pyridine bases, exhibiting the most optimized enhancing effect on directly driving the coassembly of DNA origami in FP cavities. This work sheds light on the quantum mechanism in life and in turn holds great promise to develop innovative techniques to regulate life.
Physical binding-mediated organic dye direct-labelling of proteins could be a promising technology for bio-nanomedical applications. Upon binding, it was found that fluorescence resonance energy transfer (FRET) occurred between donor bovine serum albumin (BSA; an amphiphilic protein) and acceptor fluoresceinamine (FA; a hydrophobic fluorophore), which could explain fluorescence quenching found for BSA. FRET efficiency and the distance between FA and BSA tryptophan residues were determined to 17% and 2.29 nm, respectively. Using a spectroscopic superimposition method, the saturated number of FAs that bound to BSA was determined as eight to give a complex formula of FA8-BSA. Finally, molecular docking between BSA and FA was conducted, and conformational change that occurred in BSA upon binding to FA molecules was also studied by three-dimensional fluorescence microscopy.
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