Chitosan-Aflatoxins B1, M1 Interaction: A Computational Approach

Contamination by aflatoxins affects food; especially cereal grains are affected by aflatoxin AfB1, while AfM1 affects milk. Many efforts have been addressed to face the problem. In a recent study, we have experimentally showed that the biopolymer chitosan is capable to adsorb the AfB1; however, more sensing and capturing studies are required. In this work, the aflatoxins mentioned above and their interaction with chitosan is computationally investigated. Density Functional Theory as implemented in the GAUSSIAN 09 code is employed. The B3LYP functional together with the 6-31g(d) basis set are enough to model these interactions. Through a total energy calculation, it was found that the more negative charge is on the oxygen atoms of aflatoxins, being the preferred site to interact with chitosan. According to the adsorption energy, aflatoxins are physisorbed which is confirmed by the simulated IR spectra. Modification onto the HOMO-LUMO gap as well as a little shift on the simulated infrared spectra suggests sensing applications of chitosan for these aflatoxins.