Metallo-Polyelectrolytes: Correlating Macromolecular Architectures with Properties and Applications

Facial amphiphilic naphthoic acid-derived antimicrobial polymers against multi-drug resistant gram-negative bacteria and biofilms

Inspired by the facial amphiphilic nature and antimicrobial efficacy of many antimicrobial peptides, this work reported facial amphiphilic bicyclic naphthoic acid derivatives with different ratios of charges to rings that were installed onto side chains of poly(glycidyl methacrylate). Six quaternary ammonium-charged (QAC) polymers were prepared to investigate the structure-activity relationship. These QAC polymers displayed potent antibacterial activity against various multi-drug resistant (MDR) gram-negative pathogens such as Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii. Polymers demonstrated low hemolysis and high antimicrobial selectivity. Additionally, they were able to eradicate established biofilms and kill metabolically inactive dormant cells. The membrane permeabilization and depolarization results indicated a mechanism of action through membrane disruption. Two lead polymers showed no resistance from MDR-P. aeruginosa and MDR-K. pneumoniae. These facial amphiphiles are potentially a new class of potent antimicrobial agents to tackle the antimicrobial resistance for both planktonic and biofilm-related infections.

Polycobaltoceniumylmethylene - A Water-Soluble Polyelectrolyte Prepared by Ring-Opening Transmetalation Polymerization

The synthesis of a water-soluble polycobaltoceniumylmethylene chloride (PCM-Cl) via ring-opening transmetalation polymerization is presented. Starting from a carba[1]magnesocenophane and cobalt(II) chloride, this route gives access to a polymer with methylene-bridged cobaltocenium moieties within the polymers' main-chain. The polymer was characterized by NMR spectroscopy, elemental analysis, TGA, DSC, XRD, and CV measurements, as well as UV-vis spectroscopy. Furthermore, GPC measurements in an aqueous eluent versus pullulan standards were conducted to gain insight into the obtained molar masses and distributions. In addition, the ion-dependent solubility was demonstrated by anion exchange, tuning the hydrophobic/hydrophilic properties of this redox-responsive material.

Antifouling and antimicrobial cobaltocenium-containing metallopolymer double-network hydrogels

Compared with single-network hydrogels, double-network hydrogels offer higher mechanical strength and toughness. Integrating useful functions into double-network hydrogels can expand the portfolios of the hydrogels. We report the preparation of double-network metallopolymer hydrogels with remarkable hydration, antifouling, and antimicrobial properties. These cationic hydrogels are composed of a first network of cationic cobaltocenium polyelectrolytes and a second network of polyacrylamide, all prepared via radical polymerization. Antibiotics were further installed into the hydrogels via ion-complexation with metal cations. These hydrogels exhibited significantly enhanced hydration, compared with polyacrylamide-based hydrogels, while featuring robust mechanical strength. Cationic metallopolymer hydrogels exhibited strong antifouling against oppositely charged proteins. These antibiotic-loaded hydrogels demonstrated a synergistic effect on the inhibition of bacterial growth and antifouling of bacteria, as a result of the unique ion complexation of cobaltocenium cations.

Chemical syntheses of bioinspired and biomimetic polymers toward biobased materials

The rich structures and hierarchical organizations in nature provide many sources of inspiration for advanced material designs. We wish to recapitulate properties such as high mechanical strength, colour-changing ability, autonomous healing and antimicrobial efficacy in next-generation synthetic materials. Common in nature are non-covalent interactions such as hydrogen bonding, ionic interactions and hydrophobic effects, which are all useful motifs in tailor-made materials. Among these are biobased components, which are ubiquitously conceptualized in the space of recently developed bioinspired and biomimetic materials. In this regard, sustainable organic polymer chemistry enables us to tune the properties and functions of such materials that are essential for daily life. In this Review, we discuss recent progress in bioinspired and biomimetic polymers and provide insights into biobased materials through the evolution of chemical approaches, including networking/crosslinking, dynamic interactions and self-assembly. We focus on advances in biobased materials; namely polymeric mimics of resilin and spider silk, mechanically and optically adaptive materials, self-healing elastomers and hydrogels, and antimicrobial polymers.

Biodegradable polycaprolactone metallopolymer-antibiotic bioconjugates containing phenylboronic acid and cobaltocenium for antimicrobial application

This paper reports antimicrobial metallopolymers containing biodegradable polycaprolactone as the backbone with boronic acid and cobaltocenium as the side chain. While boronic acid promotes interactions with bacterial cells via boronolectin with lipopolysaccharides, cationic cobaltocenium facilitates the unique complexation with anionic β-lactam antibiotics. The synergistic interactions in these metallopolymer-antibiotic bioconjugates were evidenced by re-sensitized efficacy of penicillin-G against four different Gram-negative bacteria (E. coli, P. vulgaris, P. aeruginosa and K. pneumoniae). The degradability of the polyester backbone was validated through tests under physiological pH (7.4) and acidic pH (5.5) or under enzymatic conditions. These metallopolymers exhibited time-dependent uptake and reduction of cobalt metals in different organs of mice via in vivo absorption, distribution, metabolism, and excretion (ADME) tests.

Mechanochemistry of Cationic Cobaltocenium Mechanophore

Recent research on the mechanochemistry of metallocene mechanophores has shed light on the force-responsiveness of these thermally and chemically stable organometallic compounds. In this work, we report a combination of experimental and computational studies on the mechanochemistry of main-chain cobaltocenium-containing polymers. Ester derivatives of the cationic cobaltocenium, though isoelectronic to neutral ferrocene, are unstable in the nonmechanical control experimental conditions that were accommodated by their ferrocene analogs. Replacing the electron withdrawing C-ester linkages with electron-donating C-alkyls conferred the necessary stability and enabled the mechanochemistry of the cobaltocenium to be assessed. Despite their high bond dissociation energy, cobaltocenium mechanophores are found to be selective sites of main chain scission under sonomechanical activation. Computational CoGEF calculations suggest that the presence of a counterion to cobaltocenium plays a vital role by promoting a peeling mechanism of dissociation in conjunction with the initial slipping.

Crosslinked metallo-polyelectrolytes with enhanced flexibility and dimensional stability for anion-exchange membranes

We report a class of crosslinked metallo-polyelectrolytes as anion exchange membranes with exceptional mechanical flexibility, dimensional stability and ionic conductivity.