Nanoscale physics
Properties of ultra-thin lipid layers surrounding boron-nitride nanotube
Raczynski P.1,2, Górny K.1,2
1 Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland.
2Silesian Centre of Education & Interdisciplinary Research, 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland.

E-mail: przemyslaw.raczynski@us.edu.pl

	Despite the fact that excessive level of cholesterol may have harmful effect on human physiology it is indispensable in the body, for example it is essential for the functioning of cell membranes. Along with phospholipid, cholesterol creates an important part of biological membranes - phospholipid bilayer, the structure that protect the interior of cell from outside environment.
In the past decade the increasing numbers of attempts to use carbon nanotubes in medicine is observed. A few years ago we conducted a reconnaissance studies on the carbon nanotubes (CNT) -cholesterol and silicon carbide nanotubes (SiCNT) - cholesterol interactions. 
Currently, we extended our research toward properties of cholesterol or phospholipid layers surrounding boron-nitride nanotube (BNNT). As in the previous research, we used molecular dynamics (MD) technique. The nanotube was surrounded by thin film consisted of 15/30 cholesterol molecules or 18 POPC molecules. All studied systems were examined in five temperatures, including physiological one. Anhydrous as well as solvated systems were simulated.
The dynamical and structural observables, such as the mean square displacement, diffusion coefficient, radial distribution function and diffusion activation energy were calculated to investigate the behavior of lipids. Significant differences for cholesterol and phospholipid molecules, depending on environment hydration were observed. 
By analyzing of the mentioned above observables for CNT, SICNT and BNNT we show the different impact of each type of nanotube on the cholesterol
or phospholipid layer surrounding it.
Snapshot shows an instantaneous configuration of the system consisted of 15 cholesterols and BNNT.