Insights into the intercalative binding of benzo[b]fluoranthene with herring sperm DNA in vitro and its application

Abstract

Benzo[b]fluorathene (BbF) is one of common polycyclic aromatic hydrocarbons with strong carcinogenic and teratogenic properties and mutagenicity in the environment. In this work, the mechanism underlying the relationship between BbF and herring sperm DNA (hs–DNA) in vitro under simulated physiological conditions was studied through multi-spectroscopic approaches (fluorescence spectroscopy, UV–Vis spectroscopy, resonance scattering spectra, and circular dichroism) coupled with agarose gel electrophoresis, fluorescence microscopy, and viscosity measurements. UV–vis and fluorescence spectra results showed that the BbF–DNA complexes formed with a binding constant of 8.95 ± 0.19 × 105 L/mol, and BbF bound to DNA by intercalative binding. These findings were further confirmed through circular dichroism, potassium iodide quenching experiment, salt ion effect tests, and viscosity measurement. Obtained from the resonance scattering spectral data, the saturation value of DNA with BbF was 2.4, revealing that BbF may cause DNA damage. The thermodynamic parameters revealed that the binding process was entropically driven by the spontaneous reaction between BbF and DNA. The main stabilizing forces between BbF and DNA were van der Waals force and π-π packing. Agarose gel electrophoresis and fluorescence microscopy results intuitively verified that the interaction mode of BbF and DNA was intercalation. Moreover, on the basis of intercalative binding between BbF and DNA, DNA and magnetic beads were used to selectively capture BbF, and the removal rate of BbF was 98.76%. This study provides mechanisms underlying the toxicity of BbF and novel insights into BbF clearance methods based on BbF–DNA intercalation.