Colloid Nanoparticles and Carbon Nanotubes. What Can We Learn About Their Biomedical Application From Molecular Dynamics Simulations?

T Panczyk and L Konczak and P Wolski, MODERN PROBLEMS OF MOLECULAR PHYSICS, 197, 23-37 (2018).

DOI: 10.1007/978-3-319-61109-9_2

The behavior of a multi-walled carbon nanotube functionalized by magnetic nanoparticles through triethylene glycol chains is studied using molecular dynamics simulations. Particular attention is paid to the effect of magnetic anisotropy of nanoparticles which significantly affects the behaviour of the system under external magnetic field. The magnetization reversal process is coupled with the standard atomistic molecular dynamics equations of motion by utilizing the Neel-Brown model. The overdamped Langevin dynamics is used for the description of the inertialess magnetization displacements. The key results obtained in this study concern: an energetic profile of the system accompanying transition of a magnetic nanoparticle from the vicinity of the nanotube tip to its sidewall, the range of the magnetic anisotropy constant in which the system performs structural rearrangements, and the release dynamics of cisplatin from the interior of the nanocontainer. Another analyzed architecture uses small gold nanoparticles linked with the nanotube by hydrazone bond containing fragments. Because hydrazone bonds hydrolyze at slightly acidic pH those gold nanoparticles become chemically disconnected from the CNT at such conditions. Thus, the previously encapsulated cisplatin molecules in the CNT inner cavity can be released only at acidic pH. Analysis of the above process at the molecular scale leads to the conclusion that the feasibility of such a mechanism can be canceled by strong dispersion forces existing between gold nanoparticles and CNT. However, the presence of cisplatin in the inner cavity of the carbon nanotube strongly reduces the range of dispersion interactions. The determined properties of the studied systems strongly suggest their application in the area of nanomedicine as drug targeting and delivery nanovehicles.

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