Shape Shifting of Cup Shaped Particles on Growing poly (2‐hydroxy ethyl methacrylate) Brushes by “Grafting From” Approach and Dissipative Particle Dynamics Simulation

Abstract

Controlled bending leading to shape shifted microparticles is indispensable for the targeted biomedical applications including advanced drug/cell delivery and has been one of the major research components in biomedical area for decades. Here, we report the shape-shifting of cup-shaped particles created by electrojetting from a blend of biodegradable polylactide (PLA) and biocompatible co-polymer (poly[methylmethacrylate-co-2-(2-bromopropionyloxy)ethyl methacrylate] (poly(MMA-co-BEMA))) containing ATRP (Atom Transfer Radical Polymerization) initiating moiety, at a ratio of 75:25. Surface initiated ATRP of HEMA (2-hydroxy ethyl methacrylate) was carried out for 1 hour to immobilize self-crosslinkable poly(HEMA) brushes onto the cup shaped particles which underwent controlled bending post polymer brush growth leading to the formation of spherical ball with one small opening (hole). However, no change of shape was observed while growing non-crosslinkable hydrophilic poly(DMAEMA) (poly(2-(Dimethylamino) ethyl methacrylate)) brush from the surface of cup shaped particles. To understand the underlying phenomena of shape shifting, simulation studies were also performed. Dissipative particle dynamics (DPD) simulation of the ATRP process at the cup surface further confirmed that the use of HEMA monomer indeed led to the desired compact modified structure of the cup particle due to the crosslinking connectivity across the interface. We have also calculated the radial distribution function (RDF) and radius of gyration to study the structure of modified particles.

High Adsorption of α-Glucosidase on Polymer Brush-Modified Anisotropic Particles Acquired by Electrospraying—A Combined Experimental and Simulation Study

“…Images of “as-jetted” cup-shaped particles (before brush modification) were also captured for comparison. After surface-initiated ATRP (SIATRP), the enhancement in particle size was clearly evident from both SEM (average size9.8 μm ± 1.6) ,, and TEM images (average size8.3μm ± 1.5); however, the shape of the particles remained almost unaltered as compared to that of “as-jetted” cup particles.…”

“…It is worth noting that brushes present inside the concave surface of cup particles may not significantly contribute to the overall volume of the particles, hence hindering the post-brush size increment. Moreover, preferential brush growth onto the outside surface of cup particles may happen due to less accessibility of the monomer (DMAEMA) and thus the restricted chain growth inside the confined concave surface. , This may lead to an anisotropic distribution of the adsorbed enzyme in the case of cup particles. On the other hand, being a flat geometry, surfaces of the whole disc would be accessible for enzyme immobilization, resulting in an enhanced loading capacity for disc-shaped particles.…”

Biocompatible Anisotropic Polymeric Particles: Synthesis, Characterization, and Biomedical Applications

“…This indicated that the shape shifting process was not only shape driven but also brush selective. The whole shape shifting phenomena was further confirmed by dissipative particle dynamics simulation studies …”

“…Another interesting class of anisotropic patchy particles would be the presence of polymer-brush-modified patches onto the surface of anisotropic/isotropic particles. Recently, various research groups have shown that anisotropy can also be generated onto the particles either by spatioselective attachment of polymer brush or immobilization of polymer brush onto nonspherical (already anisotropic) particles. ,, The brush-modified particles may undergo nonuniform swelling in water, if the selected brush is hydrophilic in nature, thus bringing anisotropy to the system. Moreover, functionality of polymer brushes and their thickness, architectures, geometry of the substrate, etc., are also the crucial factors that directly affect the properties of the modified particle.…”

“…Scanning electron microscope image of cup-shaped particle polymerized at different intervals to grow PHEMA brushes (a) 0 h, (b) 15 min, (c) 1 h, (d) 3 h, and (e) 19 h. Reproduced with permission from ref . Copyright 2020 Wiley–VCH.…”