To fabricate functional surfaces structures for protein immobilization without losing biological activity, the interaction between different amino acids and metal-organic frameworks (MOFs) has been evaluated. The density functional theory (DFT-D2) calculations were used to afford a molecular description of the interaction properties of the amino acids and MOF-5 by examining the interaction energy and the electronic structure of the amino acid/MOF complexes. Strong interactions were recorded between the amino acids and MOF through their polar groups as well as aromatic rings in the gas phase. Based on the results, water molecules prevent the amino acids from approaching the active sites of MOF, causing weak attractions between them. The interaction energies were calculated by considering the basis set superposition error correction. The interaction energies obtained at the range of +11 to -13 kcal/mol, for GLY-MOF in the presence of water molecules while in the case of the gas phase the estimated values range from -5 to -57 kcal/mol. Results showed GLY molecules cannot form a stable complex in the water media. The complication of all selected AAs is found exothermic process and energetically favorable and thus can form stable complexes with the MOF-5 at the gas phase. The accuracy of the DFT-PBE model was validated against the comprehensive MP2 quantum level of theory. The evaluation of the nature of the interaction between the amino acids and MOF by the atoms-in-molecules (AIM) theory showed that the electrostatic attractions are the main force contributing to bond formation between the interacting entities. تفاصيل المقالة

The study of complexes between nanostructures and biomolecules has attracted the attention of many researchers in various fields because it can contribute to the coherent growth and widespread use of nanostructures in various technologies. One of the main goals is to fabricate structures with functional surfaces where proteins become immobilized without losing their biological activity. In this research, following a comprehensive approach, the interaction between different amino acids and metal-organic frameworks (MOFs) at atomic scale was evaluated using computational chemistry. For this purpose, density functional theory (DFT-D2) calculations was employed to afford a molecular description of the interaction properties of the amino acids and MOF-5 by examining the interaction energy and the electronic structure of the amino acid/MOF complexes. Strong interactions between the amino acids and MOF through their polar groups were reported as well as aromatic rings in the gas phase. However, findings were significantly different in solvent media, where water molecules prevent the amino acids from approaching the active sites of MOF, causing weak attractions between them. The accuracy of the DFT-PBE model of theory was validated against the comprehensive MP2 quantum level of theory. Comparing the present results with those obtained for perfect MOFs show that the binding energy of the Histidine amino acid is increased for physisorption on defected MOFs. تفاصيل المقالة