Dissipative Particle Dynamics Simulation Study on Vesicles Self‐Assembled from Amphiphilic Hyperbranched Multiarm Copolymers

Abstract

Hyperbranched multiarm copolymers (HMCs) have been shown to hold great potential as precursors in self-assembly, and many impressive supramolecular structures have been prepared through the self-assembly of HMCs in solution. However, theoretical studies on the corresponding self-assembly mechanism have been greatly lagging behind. Herein, we report the self-assembly of normal or reverse vesicles from amphiphilic HMCs by dissipative particle dynamics (DPD) simulation. The simulation disclosed both the self-assembly mechanisms and dynamics of vesicles. It indicates that the self-assembly of HMCs involves several steps, from randomly distributed unimolecular micelles to small spherical micelles, to membrane-like micelles, to finally small vesicles. The membranes are formed through the direct aggregation and lateral fusion of small micelles, and the bending and closing of the membranes give rise to small vesicles. Finally, large and steady vesicles are formed through the fusion of small vesicles. In addition, the bilayer or monolayer molecular packing modes as well as the mircrophase separation behaviors of HMCs in normal or reverse vesicles have also been studied. These simulation results explore details that cannot be observed in the experiments to a certain degree, and have extended the understanding of the vesicular self-assembly process of HMCs.

Nanocarrier systems assembled from PEGylated hyperbranched poly(arylene oxindole)

“…4A). Lateral fusion of NPs during the longer period allowed for self-assembly would result in a particle structure enclosing the free fluorescein, as previously reported for amphiphilic HBPs [1,5,6,56]. This result supports our hypothesis that the particles formed polymer vesicles composed of a bilayer membrane and a hydrophilic interior.…”

“…4B and S5, and the particles with a self-assembly time of 48 h were generally much larger than the particles formed with a self-assembly time of 4 h. This result indicated that the size and likely the structure of the particles could also be tuned by varying the time of self-assembly in THF/PBS, which is interesting when designing particles for biomedical applications. We believe that these larger particles resulted from the lateral fusion of NPs during the longer time allowed for self-assembly, as reported elsewhere [1,5,6,56]. According to the literature, these particles would be classified as hyperbranched polymer vesicles composed of a bilayer membrane and hydrophilic interior, which have previously shown their potential as DDSs [5,57], but more studies are required to confirm this hypothesis.…”

“…This indicates that about 90 % of the reactive groups would still be available for further post-assembly functionalization with bioactive molecules to form multi-potent NPs that have the potential to target specific cells [68]. In addition, by keeping the Mw of the HBP constant, the experimentally derived Mw values, percentages of functionalized end groups, and measured NP diameters provide valuable input parameters for stochastic simulation techniques such as dissipative particle dynamics [56,69]. These methods, to some extent, would allow for prediction of the impact of postgrafting hydrophobic and/or hydrophilic molecules on the surface of the NPs, but this will need further investigation.…”

CO2-breathing and piercing polymersomes as tunable and reversible nanocarriers

“…The resulted hyperbranched polymer vesicles were termed as branched-polymersomes (BPs) 29 and have unique properties such as good stability, low permeability, giant and easily tuned vesicle size, appealing solution behaviours, and facile tailorability of the properties. Extensive studies are still needed for elucidating the mechanism for the formation of BPs and verifying the results obtained using dissipative particle dynamics (DPD) simulations 30 .…”

HBP Builder: A Tool to Generate Hyperbranched Polymers and Hyperbranched Multi-Arm Copolymers for Coarse-grained and Fully Atomistic Molecular Simulations

“…The simplest type of them is to regard HBPs/HBMCs as the monodisperse polymers. For example, in the dissipative particle dynamics (DPD) simulations on the self-assembly of amphiphilic HBMCs, all the polymers have the same predetermined hyperbranched structure in the simulation box 41 42 . This monodisperse model is quite simple but is far from the fact.…”