Introduction: The interaction of nanoparticles with the cell membranes is an important determinant of their physiological effect. Such interactions were proven, mostly by experimental work, to depend on the size, charge and surface properties of nanoparticles. Simulations can bring atomic-level details on the mechanism of these interactions. Therefore, we used simulations to understand the interaction between a fluorescein isothiocyanate (FITC) functionalized gold nanoparticle (FITC-Au-NP) and a lipid bilayer.
Methods: A gold nanoparticle (10 nm) functionalized with glycine-cysteamine spacers was built using CHARMM-GUI Nanomaterial Modeler. On the spacers we additionally linked 71 FITC residues that were parameterized with CHARMM-GUI Ligand Reader & Modeler. The nanoparticle was included in a simulation system comprising a 20 x 20 nm2 POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) lipid bilayer. The distance between the nanoparticle and the bilayer was 1 nm. Steered molecular dynamics (SMD) with constant velocity was used to pull the nanoparticle through the lipid bilayer. The resulting trajectories were analyzed.
Results: The interaction energy between the FITC-Au-NP and the lipid bilayers was evaluated, showing a favorable total interaction energy that increased as the nanoparticle entered into the bilayer. The van der Waals interactions had a substantial contribution to the total interaction energy. Although smaller in value, electrostatic interactions were also attractive.
Conclusions: We modeled a FITC-Au-NP and simulated its interaction with a POPC lipid bilayer, highlighting the importance of van der Waals forces for the favorable contacts. Additional experimental and simulation work will bring more details on this interaction.
Acknowledgment: The authors acknowledge the support of UEFISCDI through project no. 81TE/2022 (PN-III-P1-1_1-TE-2021-1375-TRANS-NANO-BIO).
