Molecular Dynamics Simulation Study of Non-Ionic Surfactant-Based Nanoparticles

Abstract

In this thesis, surfactant-based self-assembled nanoparticles were investigated using molecular dynamics simulations. First, the structural properties and the encapsulation of two non-steroidal anti-inflammatory drugs (NSAIDs) - ibuprofen and indomethacin - within Triton X-100 (TX-100) micelles were investigated. The pure TX-100 micelle was found to be semi-spherical in shape, whereas the micelles in the presence of the drugs become aspherical. This effect was more significant with indomethacin, where continuous elongation of the micelle resulted in splitting it into two, which was caused by the destabilization of the micelle due to clustering of indomethacin inside of it. The results have shown that more indomethacin than ibuprofen has been solubilized. Another surfactant from the Triton X family, Triton X-114 (TX-114), which has a shorter hydrophilic PEG headgroup than TX-100, was used as a building block for the nanoparticle. The TX-114 micelle have solubilized more ibuprofen than TX-100 micelle. Furthermore, similar to the TX-100 micelle, indomethacin clusterization inside of TX-114 micelle caused a splitting of the initial micelle into two. Lastly, we investigate the effect of cross-linking between surfactants on the structural properties of micelles. In doing so, micelles containing different amounts of TX-100 and the polymer version of TX-100, Tyloxapol, consisting of 3 (trimer) and 7 (heptamer) monomers, were investigated. Structural differences and properties were investigated using various tools and in-house written Python scripts. Pure trimer and heptamer micelles stabilized quickly and have been found to be oblate in shape. Furthermore, it was found that all micelles formed by the heptamer, were stable with very small fluctuations in their RMSD. The systems containing 75% and 25% Tyloxapol trimer, were the least stable with a significant amount of water inside of the hydrophobic core. During this project, I created a Python code (still in development), that allows one to determine the location interface of nanoparticles whose shape is not spherical in nature. This code then allows one to accurately describe the structural properties of the micelle and its surroundings.

Date of Award	1 Sept 2023
Original language	English
Awarding Institution	King's College London
Supervisor	Chris Lorenz (Supervisor) & Natasha Rhys (Supervisor)