DNA-Induced Restructuring of Interfacial Water and the Hydrocarbon Chain of Different Forms of Fungicide at the Water Interface: Vibrational Sum Frequency Generation Study

Fungicides adopt different structures at the air/water interface depending on their concentration, which affects their potency against fungi. However, the nontargeted action of fungicides causes a genotoxic effect on other organisms, which is responsible for several serious diseases such as cancer, neurodegenerative disorders, and developmental problems. Hence, understanding the effect of DNA on the different structures of fungicides at the air/water interface is essential. The surface-selective vibrational sum frequency generation technique has been implemented to obtain insights into the effect of DNA on the fungicide, namely, dodine at the air/water interface. The hydrocarbon chain of dodine with an increasing concentration adopts disordered, ordered, and packed forms at the air/water interface. DNA gets closer to the positively charged head group of dodine at the air/water interface in its disordered, ordered, and packed forms by removing the interfacial water and reorganizes the hydrogen bonding of water beneath the head group of dodine. Interestingly, DNA also increases the ordering of the hydrocarbon chain of disordered and ordered dodine at the air/water interface by modulating the gauche defect and orientational ordering of the hydrocarbon chain of dodine. Unlike the disordered and ordered dodine, the addition of DNA at the packed dodine on the air/water interface does not affect the ordering of its hydrocarbon chain. The significant reorganization of the interfacial water and the hydrocarbon chain of dodine by DNA can be useful for understanding the mechanism of the nontargeted genotoxic effects of dodine.