Computational evaluation of bonding between aflatoxin B1 and smectite

Certain smectites can effectively adsorb aflatoxin B1 but the interaction between the toxin and smectites is still poorly understood. The objective of this study was to computationally evaluate the bonding mechanism between aflatoxin B1 and smectite. Geometry optimization, net atomic charge distribution, vibration frequency and vibration intensity computations were performed for aflatoxin B1 and cation–aflatoxin B1 complexes. Molecular dynamics simulation was conducted for moist and dehydrated aflatoxin B1–Na–smectite complexes. The computed energies, net atomic charge distribution, and molecular dynamics simulations consistently revealed that the two carbonyl oxygen were the most important interacting sites with exchange cations and H2O in smectite interlayer. The two dihydrofuran oxygen had much less contribution to the bonding. Substantial charge redistribution and bond length changes occurred when cation–aflatoxin B1 complexes formed. The computed vibration frequency shifts and vibration intensity changes were in excellent agreement with experimental observations reported in the literature. The calculations confirmed the importance of carbonyl groups in the bonding of aflatoxin to smectite and revealed more subtle interactions between exchange cations and the dihydrofuran oxygen.