Density Functional Theory Study of the Reaction Behavior Histidine Modified Polyamidoamine Dendrimer as Nanocarrier for Delivery of Ectoine Drug

In the present paper, the complexation of Ectoine drugs with pristine PAMAM and Histidine modified PAMAM dendrimers was investigated by density functional theory. The bond between Ectoine and PAMAM dendrimers was established via a cross-linking agent, EDC/NHS, which is associated with the formation of amides bond between the two species. The results of the modeling were obtained by B3LYP/6-311G approach for all forms of the PAMAM-drug complexes. Due to the results, the complex of ectoine-histidine modified PAMAM dendrimer turns to absorb more electrons than ectoine-PAMAM dendrimer in a water solvent. Furthermore, the topological analysis and the electron localization function show that the nature of the bond is purely covalent and their bond order is one in both phases. DOS plots of drug-dendrimers are similar to the trends of their energy gaps in two phases. In addition, the binding energy between Ectoine drug and dendrimers showed that this energy decreases from gas phase to solvent phase. The complex has displayed a meaningful improvement of electronic and structural properties. Therefore, it represented that both PAMAM dendrimers being combined with the Ectoine drug are appropriate for use in drug delivery.