Single-walled carbon nanotubes (SWCNTs) are referred to as a promising material for biocompatible devices and novel medicines. In these applications, contact between SWCNTs and blood should be expected. Serum albumin is the most abundant globular protein in mammalian blood, so it is of great importance to study the interactions of SWCNTs with major blood components such as serum albumin, as contact between them is possible with the incorporation of SWCNTs into common practice. The radiotracer technique with [3H] is highly sensitive and enables the quantification of biomolecules in complexes with nanomaterials without inducing significant changes in the biomolecule structure.
We simulated the interaction of bovine serum albumin (BSA) as a model protein with SWCNTs moderately functionalized with fluorine with Gromacs software. Partial atom charges and bond lengths were calculated with the semi-empirical quantum chemistry method PM7 with MOPAC2016 software. Thermostat, barostat and basic simulations were carried out with the Berendsen algorithm. The simulation time was 100 ns. The dynamics of changes in the secondary structure of BSA were simulated. The quantity of BSA bonded with SWCNTs was estimated with the use of the radiotracer technique, with [3H]BSA obtained with the tritium thermal activation technique.
We found that the dominant interactions between BSA and SWCNTs are hydrophobic. The fluorine atoms in the SWCNTs become involved in hydrogen bonds with His 534, Thr 539 and Ala 583 in the BSA. The mean total energy of the Coulomb and Van der Waals interactions is -364 ± 9 kJ/mol, as determined by gmx energy. The maximum absorption of BSA on the SWCNTs is 740 mg/mg, which is consistent in all the simulations and leads to the ζ-potential of the BSA–SWCNT complex changing from -10 to -16 mV as the adsorption increases.
The research was carried out using equipment from the shared research facilities of HPC computing resources at Lomonosov Moscow State University.
