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Advanced Biomaterials and Devices in Medicine
June 2016, Volume 3, Issue 1, pp 1–9
Potential of mean force analysis of short boron nitride and carbon nanotubes insertion into cell membranes
A.A. Tsukanov1*, S.G. Psakhie2,3
1 Skolkovo Institute of Science and Technologies, Moscow, 143026 Russia
2 Institute of Strength Physics and Materials Science, Siberian Branch, Russian Academy of Sciences, Tomsk, 634055 Russia
3 Tomsk Polytechnic University, Tomsk, 634050 Russia
* Corresponding author: Dr. Alexey A. Tsukanov, e-mail: a.a.tsukanov@yandex.ru
Abstract
Tubular nanostructures made of boron nitride are of great interest for nanomedicine. In particular, single-walled boron nitride nanotubes (BNNT) are considered as intracellular nanovectors that have good biocompatibility and potentially lower cytotoxicity than carbon nanoparticles. However, the nanoscale mechanisms of BNNT interaction with the cell membrane remain largely unknown. In this paper a short steered molecular dynamics study of BNNT insertion into a lipid bilayer is presented and its results are compared with the available free energy estimations for carbon nanotube (CNT) penetration. Two BNNT models having different sets of partial atomic charges (PAC) were utilized. Using potential of mean force analysis, the free energy profiles of CNT and two cases of BNNT were compared. The results show that a BNNT with partial charges of ±0.4 e has a similar free energy profile to CNT, but the depth of the free energy well is about 30% smaller than for CNT. Furthermore in contrast to membrane penetration by CNT, BNNT remains filled with water even when it is inside the lipid interior. In the second case, BNNT with PAC of ±1.05 e demonstrates hydrophilic behavior of the nanotube, and its penetration into the cell membrane is quite complicated. Moreover, in this case BNNT has a quasi-stable state on the lipid-water interface. The results suggest that BNNT is less cytotoxic than pristine CNT, however, further steered molecular dynamics investigations with lower pulling velocities and environmentally dependent PAC are necessary.
Keywords: boron nitride nanotube, cell membrane, cytotoxicity, free energy, steered molecular dynamics, potential of mean force
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