Synthesis, Characterization, and Structural Aspects of a Novel Benzo[b]fluoranthene Hapten for PAHs

Polycyclic aromatic hydrocarbons (PAHs) are of significant concern due to their carcinogenicity, teratogenicity, and mutagenicity. Currently, immunoassay techniques are an efficient tool for the detection of PAHs. Immunoassays are based on a specific reaction between antigen and antibody and rely heavily on antibody performance, which is closely related to the design and characteristics of hapten and artificial antigens. A novel benzo-[b]-fluoranthene hapten, γ-carbonyl-benzo-[b]-fluoranthene butyric acid, was synthesized, and its crystal structure was determined to be monoclinic with space group P2₁/n by single-crystal X-ray diffraction analysis. The intermolecular bonding through the O-H···O, C-H···O, C-H···π, and π···π interactions was fully quantified by Hirshfeld surface studies. Density functional theory (DFT) calculations were used to investigate the properties of the molecules, which were optimized using the B3LYP/6-31++G-(d,p) basic set to study the molecular frontier orbitals, the ADCH charge, the electrostatic potential, and the natural bonding orbitals. The HOMO-LUMO energy gap is 6.592 eV, indicating that hapten has good stability. Hapten was also characterized by FTIR and NMR and compared with the theoretical calculation. Molecular docking and molecular dynamics simulations were performed to analyze the stability of the BSA-hapten and OVA-hapten complex systems as well as the suitability for coupling, which provided a good support for the subsequent immunoassay method.