In the present work, the encapsulation process of Pyrazinamide drug into the cyclic peptide nanotubes with the different numbers of cyclic peptides as novel drug carriers is investigated using density functional theory calculations in the aqueous medium. The negative computed binding energies for all inclusion complexes reveal the stabilization of Pyrazinamide molecule inside the cavities of the nanotubes. Moreover, our computational results indicate that the interaction between Pyrazinamide molecule and the cyclic peptide nanotubes is weak; so that, the drug encapsulation process is typically physisorption. The formation of more number of conventional hydrogen bonds between the Pyrazinamide drug molecule and the active sites of the cyclic peptide nanotube's backbone facilitates the enhancement of binding affinity of the drug molecule into the nanotube with two cyclic peptides and further more stability of the inclusion complex. To characterize the nature of the intermolecular interactions through the topological parameters, the values of electron densities and their Laplacian have been analyzed using the Bader's theory of atoms in molecules. The origin charge transfer during orbital interactions within the encapsulation process of Pyrazinamide drug into cyclic peptide nanotubes is evaluated by the natural bond orbital method. The encapsulation process of Pyrazinamide in the cavity of the nanotubes imparts significant impact on the solvation energy of the drug molecule as well as cyclic peptide nanotubes which introduces the cyclic peptide nanotubes as efficient carriers for delivery of Pyrazinamide drug in nanomedicine domain.

在目前的工作中，使用密度泛函理论计算在水介质中研究了吡嗪酰胺药物在不同数目的环肽作为新型药物载体的环肽纳米管中的包封过程。所有包合物的负计算结合能表明了吡嗪酰胺分子在纳米管腔内的稳定性。此外，我们的计算结果表明，吡嗪酰胺分子与环状肽纳米管之间的相互作用较弱。因此，药物封装过程通常是物理吸附。在吡嗪酰胺药物分子和环状肽纳米管的活性位点之间形成更多数量的常规氢键 的主链有助于增强药物分子与两个环肽的纳米管的结合亲和力，并进一步提高包合物的稳定性。为了通过拓扑参数表征分子间相互作用的性质，已使用巴德分子中的原子理论分析了电子密度值及其拉普拉斯算子。通过自然键轨道法评价吡嗪酰胺药物在环肽纳米管的包封过程中在轨道相互作用过程中的原电荷转移。