Computer quantum-chemical simulation of the interaction of calcium carbonate with biopolymers

Abstract

As part of this work, computer quantum chemical modeling of the interaction of calcium carbonate with biopolymers (chitosan, hydroxyethylcellulose, hyaluronic acid) was carried out. Quantum chemical modeling was carried out using QChem software and the IQmol molecular editor. At the first stage, modeling of the calcium carbonate molecule and molecules of chitosan, methylcellulose, hydroxyethylcellulose, hyaluronic acid was carried out, then the molecular complex ―calcium carbonate - biopolymer‖ was considered, in which the interaction of calcium carbonate with biopolymers was considered as the interaction of the calcium atom in calcium carbonate with the functional groups of biopolymers. As a result, models of molecular complexes were obtained, and the values of the total energy of the molecular complex, the energy of the highest occupied and lowest free molecular orbitals, chemical hardness and the difference in the total energy of the amino acid and the molecular complex ―calcium carbonate - biopolymer‖ were calculated. As a result, it was found that chitosan, hydroxyethylcellulose, and hyaluronic acid can be used to stabilize calcium carbonate nanoparticles, which is confirmed by the values of the difference in total energy and chemical rigidity of molecular complexes. It has been shown that for chitosan the optimal interaction (∆E = 939.445 kcal/mol, ε = 0.026 eV) is the connection through the amino group attached to the C2 glucosamine residue, for hydroxyethylcellulose - the connection through the hydroxyl group attached to the C6 ethoxy group (∆E = 939.762 kcal/mol, ε = 0.036 eV), for hyaluronic acid – connection through the hydroxyl group attached to the C6 residue of N-acetylglucosamine (∆E = 939.413 kcal/mol, ε = 0.022 eV).