Validation of an MD simulation approach for electrical field responsive micelles and their application in drug delivery

In the current work, a new type of micelle is designed that has active connectivity in respond to exterior stimulus and the desired water solubility. Two end-ornamented homopolymers, polystyrene-beta-cyclodextrin (PS-β-CD) and polyethylene oxide-ferrocene (PE-FE), can aggregate as a supramolecular micelle (PS-β-CD/PE-FE) by the guest-host interactions. Our results showed that the Lennard-Jones and hydrophobic interactions are the main powerful forces for the micelle formation process. It was found that the electrical field plays a role as a driving force in the reversible assembly-disassembly of the micellar system. Moreover, for the first time, we examined the PS-β-CD/PE-FE micelle interaction as a drug delivery system with anastrozole (ANS) and mitomycin C (MIC) anti-cancer drugs. The investigation of the total energy between PS-β-CD/PE-FE micelle and drugs predicts the drug adsorption process as favorable (E_total = - 638.67 and - 259.80 kJ/mol for the Micelle@ANS and Micelle@MIC complexes, respectively). Our results offer a deep understanding of the micelle formation process, the electrical field-respond, and drug adsorption behaviors of the micelle. This simulation study has been accomplished by employing classical molecular dynamics calculation.

Insights into glyphosate removal efficiency using a new 2D nanomaterial

Glyphosate (GLY) is a nonselective herbicide that has been widely used in agriculture for weed control. However, there are potential genetic, development and reproduction risks to humans and animals associated with exposure to GLY. Therefore, the removal of this type of environmental pollutants has become a significant challenge. Some of the two-dimensional nanomaterials, due to the characteristics of hydrophilic nature, abundant highly active surficial sites and, large specific surface area are showed high removal efficiency for a wide range of pollutants. The present study focused on the adsorption behavior of GLY on silicene nanosheets (SNS). In order to provide more detailed information about the adsorption mechanism of contaminants on the adsorbent's surface, molecular dynamics (MD) and well-tempered metadynamics simulations are performed. The MD results are demonstrated that the contribution of the L-J term in pollutant/adsorbent interactions is more than coulombic energy. Furthermore, the simulation results demonstrated the lowest total energy value for system-A (with the lowest pollutant concentration), while system-D (contains the highest concentration of GLY) had the most total energy (E _tot: -78.96 vs. -448.51 kJ mol^-1). The well-tempered metadynamics simulation is accomplished to find the free energy surface of the investigated systems. The free energy calculation for the SNS/GLY system indicates a stable point in which the distance of GLY from the SNS surface is 1.165 nm.

Assessment of the effect of external and internal triggers on adsorption and release of paclitaxel from the PEI functionalized silicene nanosheet: A molecular dynamic simulation

In order to examine the adsorption mechanisms of paclitaxel (PTX) on silicene nanosheet (SNS) molecular dynamics (MD) simulations are carried out. The MD outcomes show that the adsorption of PTX on the pristine SNS is exothermic and spontaneous. The interaction between the PTX molecule and the pristine SNS is mainly due to the formation of π-π interactions through their aromatic rings, which are supplemented by X-π (X = N-H, C-H, and CO) interactions. Upon functionalization of SNS by Polyethylenimine (PEI), drug molecules prefer to bind to the nanocarrier instead of the polymer. In the functionalized SNS (f-SNS), the binding energy of the drug with the nanocarrier becomes stronger in comparison to the SNS case (E_ads: -2468.91 vs -840.95 kJ/mol). At the acidic condition, protonation of drug and PEI cause that the interaction between PTX and the nanocarrier become weaker and drug molecules could release from the nanocarrier surface. Finally, two f-SNS and protonated f-SNS (f-pSNS) systems are induced by the electric field (EF). Evaluation of the dynamic properties of these systems (with strengths 0.5 and 1 V/nm) shows that the electric field could be acted as a stimulus for drug release from nanocarriers. The obtained results from this study provide valuable information about the loading/release mechanisms of PTX on/from the SNS surface.

Molecular insights into the loading and dynamics of anticancer drugs on silicene and folic acid-conjugated silicene nanosheets: DFT calculation and MD simulation

The adsorption behavior of Anastrozole (ANA) and Melphalan (MEL) anticancer drugs on the surface of silicene nanosheet (SNS) and functionalized SNS with folic acid (FA-SNS) is investigated and compared using the density functional theory (DFT) and molecular dynamics (MD) simulation. The DFT calculation is performed at the M06-2X/6-31G** level to characterize the optimized geometry properties of the designed complexes. The calculated adsorption energies are in the range from -65.59 to -144.23 kJ/mol, indicating the drug absorption on the surface of SNS and FA-SNS is exergonic. The π-π interaction between the drugs and SNS surface is the main driving force in the formation of drug-carriers complexes. The quantum theory of atoms in molecule (QTAIM) results reveal that the interaction of SNS and FA-SNS with both drugs has a non-covalent nature. The natural bond orbital (NBO) analysis shows that the charge is transferred from the drug molecules to carrier in all of the investigated complexes. Furthermore, MD simulations reveal that the contribution of van der Waals energy in drug-carrier interactions is more than electrostatic energy. Also, the obtained results demonstrate that the movement of drug molecules toward the carriers is spontaneous. Our study provides insights into the drug delivery capability of SNS and FA-SNS for the delivery of two drugs (ANA and MEL).Communicated by Ramaswamy H. Sarma.

Comparison of the Effectiveness of MindfulnessBased Stress Reduction Group Therapy With Acceptance and Commitment Therapy on Severity of Pain and Health-Related Quality of Life in Patients With Migraine

Background: Considering the prevalence of migraine and its detrimental effects on functioning, physical health, and quality of life as well as its psychosocial and social risks. The purpose of this study was to compare the effectiveness of mindfulness-based stress reduction treatment with treatment based on acceptance and commitment to the severity of pain and health-related quality of life in migraine patients. Methods: In this study, a semi-experimental design used with pre-test, post-test, a 3-month follow-up, and a control group. Using purposive sampling and considering the inclusion criteria, 45 patients with migraine diagnosis selected from among those referring to the neurology department of Imam Hossein hospital in Tehran. They were then randomly assigned to two experimental groups and a control group. The first experimental group received group therapy based on mindfulness (n = 15; 90-minute sessions), the second experimental group received acceptance and commitment based intervention (n = 15; 90-minute sessions), and the control group (n = 15) received no intervention. All subjects responded to pain intensity and health-related quality of life questionnaires before the intervention (pre-test), after the intervention (post-test), and 3 months after the intervention (follow-up). One-way ANOVA analyzed the collected data. Results: The findings showed that mean scores for the 2 experimental groups were significantly different from the control group in the post-test and follow-up phases in terms of severity of pain and health-related quality of life, while the mean scores for the two experimental groups did not differ significantly. The results emphasize the importance of these interventions for chronic diseases and offer new horizons in clinical interventions. Conclusion: The results of this study showed that mindfulness-based stress reduction therapy and acceptance and commitment therapy could positively affect the severity of pain and health-related quality of life in migraine patients, and any of them can be used to improve the variables mentioned above.