High dose intake of fluoride results in fluorosis and our previous experiments at single-molecule level using magnetic tweezers have proved that fluoride anions destabilize DNA hairpin and its equilibrium critical force decreases with increasing concentration of fluoride anions. One possible mechanism is that a fluoride anion competes with a DNA base and forms a hydrogen bond with its complementary base. The Isothermal Titration Calorimetry experiments suggest that the fluoride anion does not form a hydrogen bond with a DNA base. With increasing concentration of fluoride anions, decreasing Zeta potentials for different oligonucleotides enhance the electrostatic repulsion between complementary oligonucleotides, which accounts for the decreasing association constant and destabilization of DNA hairpin. Molecule dynamics simulation was further performed to determine the ion distribution around the oligonucleotide, radial distribution functions (RDFs) indicate that the fluoride anion distributes far from the oligonucleotide in comparison with the chloride anion, which is the possible mechanism that decreases Zeta potentials with the increasing concentration of fluoride anions.

高剂量的氟化物摄入会导致氟中毒，我们之前使用磁性镊子在单分子水平上进行的实验证明，氟化物阴离子会使 DNA 发夹不稳定，其平衡临界力随着氟阴离子浓度的增加而降低。一种可能的机制是氟阴离子与 DNA 碱基竞争并与其互补碱基形成氢键。等温滴定量热实验表明，氟阴离子不会与 DNA 碱基形成氢键。随着氟阴离子浓度的增加，不同寡核苷酸的 Zeta 电位降低会增强互补寡核苷酸之间的静电排斥，这导致了 DNA 发夹结合常数的降低和不稳定。