Molecular mechanism for the encapsulation of the doxorubicin in the cucurbit[n]urils cavity and the effects of diameter, protonation on loading and releasing of the anticancer drug:Mixed quantum mechanical/ molecular dynamics simulations

BACKGROUND AND OBJECTIVES

Doxorubicin is a common apoptotic chemotherapeutic which has shown an obvious inhibitory effect in cancer chemotherapy. Here, cucurbit[n]urils (n = 7,10) have been proposed as a doxorubicin carrier, and the effects of diameter, protonation on loading and releasing of the anticancer drug doxorubicin has been studied.

METHODS

The Density Functional Theory (DFT) calculation and Molecular Dynamics (MD) simulation are performed to study the adsorption process of the (guest) Doxorubicin molecule in the neutral and protonated states within the (host) cucurbit[n]urils (n = 7,10).

RESULTS

DFT results show that the adsorption process in water is thermodynamically favorable. It is found that the binding energies for protonated drug encapsulation in cucurbit[n]urils are weaker than those of the neutral drug, implying the protonation of doxorubicin can promote the drug release from the adsorption situation. The electron density values and their Laplacian are evaluated to identify the nature of the intermolecular interactions through the topological parameters using the Bader's theory of atoms in molecules. Furthermore, the natural bond orbital analysis shows that the electrons aretransferred from cucurbit[n]urils to drug in all complexes. MD simulation results indicate that value of drug diffusion coefficient is small, therefore, we expect DOX to be slowly released from the CB cavity.

CONCLUSIONS

Based on obtained results, cucurbit[n]urils may be a prominent nano-carrier to loading and release drug on to target cells.

Carbon and boron nanotubes as a template material for adsorption of 6-Thioguanine chemotherapeutic: a molecular dynamics and density functional approach

The interaction of 6-Thioguanine molecule, an antitumor drug with carbon nanotube and boron nitride nanotube (BNNT) is investigated using molecular dynamics simulations. Based on the obtained results, the strongest negative van der Waals interaction is found between 6-TG and BNNT among the studied nanotubes, which indicated BNNT is a better nanocarrier of the 6-TG drug than CNT within biological systems. Moreover, the adsorption and electronic properties of the 6-Thioguanine interacted with boron-nitride nanotube has been studied within the framework of density functional theory calculations. The negative binding energy values denote that there is the favorable interaction between 6-TG drug and BNNT at the studied 6-TG/BNNT complexes. Also, the amounts of the binding energies indicated that the 6-Thioguanine molecule physically interacts with the surface of BNNT. The values of electron densities and their Laplacian have been analyzed using the Bader's theory of atoms in molecules to characterize the nature of the intermolecular interactions through the topological parameters. We hope that the results of this work may provide useful information about the nature of the nanotube-drug molecule interactions and highlight the ability of these materials to be used as an adsorbent enhancing delivery of drug to cancer cells. Communicated by Ramaswamy H. Sarma.

Assessment of the chitosan-functionalized graphene oxide as a carrier for loading thioguanine, an antitumor drug and effect of urea on adsorption process: Combination of DFT computational and molecular dynamics simulation studies

In this study, the interaction thioguanine (TG) anticancer drug with the functionalized graphene oxide (GO) nanosheet surface is theoretically studied in both gas phase and separately in physiological media using the density functional theory (DFT) calculations. DFT calculations indicated the adsorption and solvation energies are negative for f-GONS/TG complexes which propose the adsorption process of TG molecule onto the f-GONS surface is possible from the energetic viewpoint. QTAIM calculations confirm the nature of partially covalent-partially electrostatic between drug and nanosheet. These results are sorely relevant that an approach for loading of TG molecule is the chemical modification of GO using covalent functionalization which can serve as a nanocarrier to load drug molecules. Moreover, to understand the effect of urea on the nature of the interaction between TG and f-GONS, molecular dynamics (MD) simulation was employed. The results indicated that in the presence of urea the adsorption process gets affected and leads to instability of system, while the affinity of the TG for adsorption onto GO surface is increased in pure water. Communicated by Ramaswamy H. Sarma.