Grafting Branch Length and Density Dependent Performance of Zwitterionic Polymer Decorated Polypropylene Membrane

Developing multifunctional zwitterionic-xanthan gum-anchored network copolymers for biomedical applications

Herein, mucoadhesive and biocompatible network hydrogels were developed by grafting zwitterionic polymer poly(2-[(methacryoyloxy)ethyl]dimethyl (3-sulfopropyl) ammonium hydroxide (poly(MEDSAH)) onto bacterial-derived polysaccharide xanthan gum (XG) via free radical graft polymerization, followed by crosslinking with N,N'-methylene bisacrylamide (NNMBA). The developed polymeric hydrogels were characterized using XRD, FTIR, 13C-NMR, TGA-DSC, FESEM, EDX and AFM analyses. FESEM and AFM analyses of these hydrogels demonstrated morphological heterogeneous features with surface roughness. Augmentation in the atomic percentages of sulfur and nitrogen atoms in the EDX spectrum of the polymers and the appearance of the characteristic spectral peaks (FTIR and 13C-NMR) of the sulfonic and quaternary ammonium groups of poly(MEDSAH) confirmed the grafting of zwitterionic polymer on the XG backbone. The crosslinked product exhibited modified XRD and thermal degradation (TGA-DSC) patterns, as compared to native XG polysaccharide. The slow and gradual release of ertapenem was observed through supra-molecular interactions and occurred more frequently under neutral to slightly basic conditions. The drug release from the network hydrogels followed non-Fickian type diffusion and was best defined by the Higuchi model. The developed hydrogel-based drug delivery (DD) carriers were found to be bioadhesive with 100.0 ± 5.0 mN force of adhesion, biocompatible with 1.078 ± 0.073% haemolytic index and antioxidant in nature by displaying 28.384 ± 0.963% inhibition during DPPH assay. The physicochemical and biomedical properties of XG-based hydrogels are indicative features for their utilization in gastrointestinal DD applications.

Tethering zwitterionic polymer coatings to mediated glucose biosensor enzyme electrodes can decrease sensor foreign body response yet retain sensor sensitivity to glucose

Foreign body response (FBR) is a major challenge that affects implantable biosensors and medical devices, including glucose biosensors, leading to a deterioration in device response over time. Polymer shields are often used to mitigate this issue. Zwitterionic polymers (ZPs) are a promising class of materials that reduce biofouling of implanted devices. A series of ZPs each containing tetherable epoxide functional groups was synthesised for application as a polymer shield for eventual application as implantable glucose biosensors. The polymer shields were initially tested for the ability to resist fibrinogen adsorption and fibroblast adhesion. All synthesised ZPs showed comparable behaviour to a commercial Lipidure ZP in resisting fibrinogen adsorption. Nafion, a common anionic shield used against electrochemical interferents, showed higher protein adsorption and comparable cell adhesion resistance as uncoated control surfaces. However, a poly(2-methacryloyloxyethyl phosphorylcholine-co-glycidyl methacrylate) (MPC)-type ZP showed similar behaviour to Lipidure, with approximately 50% reduced fibrinogen adsorption and 80% decrease in fibroblast adhesion compared to uncoated controls. An MPC-coated amperometric glucose biosensor showed comparable current density and a 1.5-fold increase in sensitivity over an uncoated control biosensor, whereas all other polymer shields tested, including Lipidure, Nafion and a poly(ethyleneglycol) polymer, resulted in lower sensitivity and current density. Collectively, these characteristics make MPC-polymer shield coatings an appealing possibility for use in implantable glucose sensors and other implanted devices with the aim of reducing FBR while maintaining sensor performance.

Interactions on Proteins Arising from the Self-Assembly of a Polyelectrolyte Brush

Surfaces grafted with polyelectrolyte chains for excellent performance in protein antifouling are highly desired in many applications, such as biomedical implants and devices. In general, the adsorbing/resisting behaviors of proteins can be mainly attributed to the electrostatic interactions that are associated with the charge properties of proteins and polyelectrolytes. By coarse-grained molecular dynamics simulations, we examined the self-assembled structures of polyanion and polyzwitterion brushes as well as the interactions on negatively and positively charged proteins. We found that in addition to charges, the structural polarization induced by self-assembly with a certain charge distribution shows significant influences on protein behavior. The large-scale dipole-dipole interactions between brushes and proteins can dominate the behavior of proteins on the brushes under certain circumstances. To ensure simulation accuracy, we compared two models and found a polar Martini model that explicitly treats electrostatic interactions as long-ranged ones, giving a more reasonable structural description compared with the normal Martini model that truncates electrostatic interactions.

Dual-responsive zwitterion-modified nanopores：a mesoscopic simulation study

In this work, dissipative particle dynamics simulation was carried out to investigate the intelligent switching effect of nanopores grafted by the zwitterionic polymer brushes poly(carboxybetaine) with excellent antifouling property. The...

Effect of the Self-Assembled Structures of Hydrated Polyzwitterionic and Polyanionic Brushes on Their Self-Cleaning Capabilities

The capability of polyelectrolyte brushes to spontaneously clean oil fouling via water is determined by factors including water wettability and the self-assembled structures of hydrated polyelectrolytes. Although the charged groups of polyelectrolytes provide the original source of water wettability, the self-assembled structures play a significant role in the self-cleaning performances. Here, we employ coarse-grained molecular dynamics simulations to study the general self-cleaning characteristics of two types of surface-grafted polyelectrolyte brushes (i.e., zwitterionic and anionic polyelectrolytes). It has been found that the high grafting density is favorable to fouling reduction for both polyzwitterions and polyanions. To be specific, the hydrated polyzwitterions form an intermolecular cross-linked network via zwitterionic complexes, resulting in better self-cleaning capabilities than the polyanions at lower grafting densities. However, polyanions form bundles with each consisting of several chains via hydrophobic interactions and electrostatic repulsions presenting better self-cleaning performances than the polyzwitterions at higher grafting densities.

An introduction to zwitterionic polymer behavior and applications in solution and at surfaces

Zwitterionic polymers, including polyampholytes and polybetaines, are polymers with both positive and negative charges incorporated into their structure. They are a unique class of smart materials with great potential in a broad range of applications in nanotechnology, biomaterials science, nanomedicine and healthcare, as additives for bulk construction materials and crude oil, and in water remediation. In this Tutorial Review, we aim to highlight their structural diversity and design criteria, and their preparation using modern techniques. Their behavior, both in solution and at surfaces, will be examined under a range of environmental conditions. Finally, we will exemplify how their unique behaviors give rise to specific properties tailored to a selection of their numerous applications.

The emerging applications of click chemistry reactions in the modification of industrial polymers

Click chemistry reactions have been applied to the modification of major industrial polymers by analysing the synthetic approaches and the resulting material properties.