Interaction and structural stability of DNA in choline chloride and polyol-based deep eutectic solvents

Deep eutectic solvents (DESs) have emerged as viable eco-friendly substitutes to traditional solvents for biomolecular applications, due to their biodegradability, less toxicity, and tunable physicochemical characteristics. Use of DESs as greener media for preserving DNA structure and stability is currently a topic of immense importance, as it provides a better potential in the domain of DNA biotechnology. Here, we explored the interaction and structural integrity of DNA within various choline chloride and polyol-based DES media. Synthesized DESs were characterized, and their key physicochemical properties were evaluated. CD-spectroscopic study suggests that DNA maintains its conformational structure, stacking, and preserves its native B-form in all studied DESs, even at higher DES concentrations. Results were additionally supported by fluorescence microscopic studies. DESs exhibited multiple interaction pathways with DNA. UV-Vis spectroscopic studies revealed that phosphate group of DNA interacts with the choline cation of DESs via electrostatic force of attraction. DNA melting study unveils stability of DNA even at higher temperatures in polyol-based DESs. The dye displacement assay suggests binding of DNA in minor grooves and intercalation as DESs displaced both Ethidium bromide and Hoechst dye as measured by Stern-Volmer constant. To understand the binding efficiency between DNA and DES constituents, molecular docking was performed. Results reveal that tetraethyleneglycol had the highest favorable binding energy, followed by PEG400 and glycerol. These results offer novel perspectives into the solvation behavior of DNA in DES environments and establish a fundamental framework for their potential application in nanobiotechnology, extraction, and preservation of DNA.