Introduction: Chemotherapy with anti-cancer drugs is considered the most common approach for killing cancer cells in the human body. However, some barriers such as toxicity and side effects would limit its usage. In this regard, nano-based drug delivery systems have emerged as cost-effective and efficient for sustained and targeted drug delivery. Nanotubes such as carbon nanotubes (CNT) and boron nitride nanotubes (BNNT) are promising nanocarriers that provide the cargo with a large inner volume for encapsulation. However, understanding the insertion process of the anti-cancer drugs into the nanotubes and demonstrating drug-nanotube interactions starts with theoretical analysis. Methods: First, interactions parameters of the atoms of 5-FU were quantified from the DREIDING force field. Second, the storage capacity of BNNT (8,8) was simulated to count the number of drugs 5-FU encapsulated inside the cavity of the nanotubes. In terms of the encapsulation process of the one drug 5-FU into nanotubes, it was clarified that the drug 5-FU was more rapidly adsorbed into the cavity of the BNNT compared with the CNT due to the higher van der Waals (vdW) interaction energy between the drug and the BNNT. Results: The obtained values of free energy confirmed that the encapsulation process of the drug inside the CNT and BNNT occurred spontaneously with the free energies of −14 and −25 kcal·mol⁻¹, respectively. Discussion: However, the lower value of the free energy in the system containing the BNNT unraveled more stability of the encapsulated drug inside the cavity of the BNNT comparing the system having CNT. The encapsulation of Fluorouracil (5-FU) anti-cancer chemotherapy drug (commercial name: Adrucil^®) into CNT (8,8) and BNNT (8,8) with the length of 20 Å in an aqueous solution was discussed herein applying molecular dynamics (MD) simulation.

In the present study, the radial thermal rectification and thermal conductivity of the graphene were investigated by non-equilibrium molecular dynamics simulation and then corrected by quantum correction to make it closer to the fact. The Optimised three-body Tersoff potential is employed in order to simulate the interactions between the carbon atoms in the graphene sheet. A circular region in the centre and the one at the graphene edge are selected as hot and cold bath to generate radial temperature gradient. It is observed that the heat current passes through radially inward direction than outward with the same temperature gradient and hence there is a radial thermal rectification in graphene. Also, temperature distribution and heat flux are theoretically introduced as a function of distance from the graphene centre and then it is confirmed by the molecular dynamics simulation data. Finally, the influence of temperature gradient and size of graphene on radial thermal rectification and the impact of size on the radial thermal conductivity is investigated.

Introduction: Nanotube-based drug delivery systems have received considerable attention because of their large internal volume to encapsulate the drug and the ability to penetrate tissues, cells, and bacteria. In this regard, understanding the interaction between the drug and the nanotube to evaluate the encapsulation behavior of the drug in the nanotube is of crucial importance. Methods: In this work, the encapsulation process of the cationic antimicrobial peptide named cRW3 in the biocompatible boron nitride nanotube (BNNT) was investigated under the Canonical ensemble (NVT) by molecular dynamics (MD) simulation. Results: The peptide was absorbed into the BNNT by van der Waals (vdW) interaction between cRW3 and the BNNT, in which the vdW interaction decreased during the simulation process and reached the value of − 142.7 kcal·mol^{− 1} at 4 ns. Discussion: The increase in the potential mean force profile of the encapsulated peptide during the pulling process of cRW3 out of the nanotube showed that its insertion into the BNNT occurred spontaneously and that the inserted peptide had the desired stability. The energy barrier at the entrance of the BNNT caused a pause of 0.45 ns when half of the peptide was inside the BNNT during the encapsulation process. Therefore, during this period, the peptide experienced the weakest movement and the smallest conformational changes.

Simulation of thermal properties of graphene hetero-nanosheets is a key step in understanding their performance in nano-electronics where thermal loads and shocks are highly likely. Herein we combine graphene and boron-carbide nanosheets (BC3N) heterogeneous structures to obtain BC3N-graphene hetero-nanosheet (BC3GrHs) as a model semiconductor with tunable properties. Poor thermal properties of such heterostructures would curb their long-term practice. BC₃GrHs may be imperfect with grain boundaries comprising non-hexagonal rings, heptagons, and pentagons as topological defects. Therefore, a realistic picture of the thermal properties of BC₃GrHs necessitates consideration of grain boundaries of heptagon-pentagon defect pairs. Herein thermal properties of BC₃GrHs with various defects were evaluated applying molecular dynamic (MD) simulation. First, temperature profiles along BC₃GrHs interface with symmetric and asymmetric pentagon-heptagon pairs at 300 K, ΔT = 40 K, and zero strain were compared. Next, the effect of temperature, strain, and temperature gradient (ΔT) on Kaptiza resistance (interfacial thermal resistance at the grain boundary) was visualized. It was found that Kapitza resistance increases upon an increase of defect density in the grain boundary. Besides, among symmetric grain boundaries, 5–7–6–6 and 5–7–5–7 defect pairs showed the lowest (2 × 10^–10 m² K W⁻¹) and highest (4.9 × 10^–10 m² K W⁻¹) values of Kapitza resistance, respectively. Regarding parameters affecting Kapitza resistance, increased temperature and strain caused the rise and drop in Kaptiza thermal resistance, respectively. However, lengthier nanosheets had lower Kapitza thermal resistance. Moreover, changes in temperature gradient had a negligible effect on the Kapitza resistance.

We investigate thermal rectification and thermal resistance in a hybrid pillared-graphene and graphene (PGG) system by both molecular dynamics (MD) simulation and a continuum model. First, the thermal conductivity of both pillared-graphene and graphene is calculated by employing MD simulation and Fourier’s law. Our results show that the thermal conductivity of the pillared-graphene is much smaller than that of graphene by one order of magnitude. Next, by applying positive and negative temperature gradients along the longitudinal direction of the PGG, the thermal rectification is examined. The MD results indicate that for the lengths in the range of 3686 nm, the thermal rectification remains almost constant (~3%–5%). We have also studied the phonon density of states (DOS) on both sides of the interface of PGG. The DOS curves show that there is phonon scattering at low frequencies that depends on the imposed temperature gradient direction in the system. Therefore, we can introduce the PGG as a thermal rectifier at room temperature. Furthermore, next, we also explore the temperature distribution over the PGG by using the continuum model. The results obtained from the continuum model predict the MD results, such as the temperature distribution in the upper half-layer and lower full-layer graphene, the temperature gap, and also the thermal resistance at the interface. This study could help in the design of chip coolers, and phononic devices such as thermal nanodiodes.

Introduction: Carbon nanotubes (CNTs) have been widely employed as biomolecule carriers, but there is a need for further functionalization to broaden their therapeutic application in aqueous environments. A few reports have unraveled biomolecule–CNT interactions as a measure of response of the nanocarrier to drug-encapsulation dynamics. Methods: Herein, the dynamics of encapsulation of the antimicrobial peptide HA-FD-13 (accession code 2L24) into CNTs and hydroxylated CNTs (HCNTs) is discussed. Results: The van der Waals (vdW) interaction energy of CNT–peptide and HCNT–peptide complexes decreased, reaching − 110.6 and − 176.8 kcal.Mol^{− 1}, respectively, once encapsulation of the peptide inside the CNTs had been completed within 15 ns. The free energy of the two systems decreased to − 43.91 and − 69.2 kcal.Mol^{− 1} in the same order. Discussion: The peptide was encased in the HCNTs comparatively more rapidly, due to the presence of both electrostatic and vdW interactions between the peptide and HCNTs. However, the peptide remained encapsulated throughout the vdW interaction in both systems. The negative values of the free energy of the two systems showed that the encapsulation process had occurred spontaneously. Of note, the lower free energy in the HCNT system suggested more stable peptide encapsulation.