Recent Advances in Zwitterionic Hydrogels: Preparation, Property, and Biomedical Application

Nonspecific protein adsorption impedes the sustainability of materials in biologically related applications. Such adsorption activates the immune system by quick identification of allogeneic materials and triggers a rejection, resulting in the rapid failure of implant materials and drugs. Antifouling materials have been rapidly developed in the past 20 years, from natural polysaccharides (such as dextran) to synthetic polymers (such as polyethylene glycol, PEG). However, recent studies have shown that traditional antifouling materials, including PEG, still fail to overcome the challenges of a complex human environment. Zwitterionic materials are a class of materials that contain both cationic and anionic groups, with their overall charge being neutral. Compared with PEG materials, zwitterionic materials have much stronger hydration, which is considered the most important factor for antifouling. Among zwitterionic materials, zwitterionic hydrogels have excellent structural stability and controllable regulation capabilities for various biomedical scenarios. Here, we first describe the mechanism and structure of zwitterionic materials. Following the preparation and property of zwitterionic hydrogels, recent advances in zwitterionic hydrogels in various biomedical applications are reviewed.

A deeper exploration of the relation between sulfonation degree and retanning performance of aromatic syntans

It is well-known that the sulfonation degree (DS) of aromatic syntan is an important factor affecting its retanning performances. But the quantitative relation between DS and syntan property and the influencing mechanism of DS on syntan property are not clarified. In this work, five phenolic formaldehyde syntans (PFSs) with the same polymerization degree but varying DS were prepared to investigate the effect of DS on the properties of syntan and crust leather. It was found that the absolute value of zeta potential and the particle size of PFS decreased with increasing DS in aqueous solution. Molecular dynamic simulation results proved that the DS of PFS was a major contributor to electrostatic interaction and hydrogen bonding in the PFS–water system and greatly affected the aggregation and dispersion of PFS in aqueous solution. The PFS with a low DS was prone to aggregate to large particles in aqueous solution because of low intermolecular electrostatic repulsion and less hydrogen bonds and therefore can be used to increase the thickness and tightness of leather. The PFS with a high DS presented a small particle size with more anionic groups in aqueous solution, thereby sharply decreasing the positive charge of leather surface and facilitating the penetration of the post-tanning agents into the leather. These results might be scientifically valid for rational molecular design of syntans and more productive use of syntans in leather making. Graphical Abstract

Polybetaines in Biomedical Applications

Polybetaines, that have moieties bearing both cationic (quaternary ammonium group) and anionic groups (carboxylate, sulfonate, phosphate/phosphinate/phosphonate groups) situated in the same structural unit represent an important class of smart polymers with unique and specific properties, belonging to the family of zwitterionic materials. According to the anionic groups, polybetaines can be divided into three major classes: poly(carboxybetaines), poly(sulfobetaines) and poly(phosphobetaines). The structural diversity of polybetaines and their special properties such as, antifouling, antimicrobial, strong hydration properties and good biocompatibility lead to their use in nanotechnology, biological and medical fields, water remediation, hydrometallurgy and the oil industry. In this review we aimed to highlight the recent developments achieved in the field of biomedical applications of polybetaines such as: antifouling, antimicrobial and implant coatings, wound healing and drug delivery systems.

A Structure Hierarchy for the Aluminofluoride Minerals

ABSTRACT The structure hierarchy hypothesis states that structures may be ordered hierarchically according to the polymerization of coordination polyhedra of higher bond-valence, and such hierarchies are useful in understanding the general compositional, structural, and paragenetic variations within the structural group of interest. Here we develop a structure hierarchy for the aluminofluoride minerals based on the polymerization of the dominant (AlΦ6) octahedra and their linkage with other strongly bonded complex anionic groups. The minerals are divided first into the following categories: (1) simple aluminofluorides and (2) compound aluminofluorides containing other oxyanions. The minerals are then ordered according to the polymerization of the constituent polyhedra into a coherent structural hierarchy. The chemical composition and crystal-chemical details of the ions of the interstitial complex are a collective function of the Lewis acidity of the interstitial cations; the presence of interstitial anions, both simple [F–, (OH)–] and complex [(SO4)2–]; self-polymerization of the (AlF6)3– octahedra; and polymerization with both Mg(F,OH)6 octahedra and other complex anions: (SO4)2–, (PO4)3–, (CO3)2–.

Enhanced Birefringence and Suppressed Second Harmonic Generation Response Mechanism in Nonlinear Optical Materials via Structural Fine-Tuning

The microscopic anionic groups with special arrangement are crucial in determining optical properties of optical functional materials. The responses of linear and nonlinear polarization from external field change synchronously, while...

The function of peptide-mimetic anionic groups and salt bridges in the antimicrobial activity and conformation of cationic amphiphilic copolymers

Amino acid-mimetic anionic groups and salt bridges in cationic amphiphilic copolymers control the polymer conformation and dynamics in solution.

Motion Restricted by Hydration Shell: A Self-Reporting System for Visualizing Electrolyte Interactions

<div><div><div><p>Electrolyte interaction is of pivotal importance for chemical, biochemical, and environmental processes, including cellular signal transduction, DNA attraction, and protein dynamics. Although its investigation has been at the focus of extensive research, direct visualization of electrolyte interaction at the molecular level is exceptionally challenging. Here, we report a highly sensitive and readily-accessible technique to visualize the electrolyte interactions in water through molecular design and fluorescence spectroscopy. Two water-soluble luminogens with either cationic or anionic groups are designed as electrolyte models. The hydration shell of isolated luminogens is able to restrict their intramolecular motion, which enhances the emission. Consequently, the occurred electrolyte interactions can be optically detected since they affect the reorientation dynamics of water molecules in the hydration shell and vary the restriction strength on the intramolecular motion of the luminogens. Moreover, this technology allows us to reveal how electrolyte interaction affects the internal motion of an electrolyte within its hydration shell, which has rarely been achieved through experimental approaches.</p></div></div></div>

Motion Restricted by Hydration Shell: A Self-Reporting System for Visualizing Electrolyte Interactions

<div><div><div><p>Electrolyte interaction is of pivotal importance for chemical, biochemical, and environmental processes, including cellular signal transduction, DNA attraction, and protein dynamics. Although its investigation has been at the focus of extensive research, direct visualization of electrolyte interaction at the molecular level is exceptionally challenging. Here, we report a highly sensitive and readily-accessible technique to visualize the electrolyte interactions in water through molecular design and fluorescence spectroscopy. Two water-soluble luminogens with either cationic or anionic groups are designed as electrolyte models. The hydration shell of isolated luminogens is able to restrict their intramolecular motion, which enhances the emission. Consequently, the occurred electrolyte interactions can be optically detected since they affect the reorientation dynamics of water molecules in the hydration shell and vary the restriction strength on the intramolecular motion of the luminogens. Moreover, this technology allows us to reveal how electrolyte interaction affects the internal motion of an electrolyte within its hydration shell, which has rarely been achieved through experimental approaches.</p></div></div></div>