Parasmani Pageni

Anion-Responsive Metallopolymer Hydrogels for Healthcare Applications

Metallopolymers combine a processable, versatile organic polymeric skeleton with functional metals, providing multiple functions and methodologies in materials science. Taking advantage of cationic cobaltocenium as the key building block, organogels could be simply switched to hydrogels via a highly efficient ion exchange. With the unique ionic complexion ability, cobaltocenium moieties provide a robust soft substrate for recycling antibiotics from water. The essential polyelectrolyte nature offers the metallopolymer hydrogels to kill multidrug resistant bacteria. The multifunctional characteristics of these hydrogels highlight the potential for metallopolymers in the field of healthcare and environmental treatment.

Recent Advances in Metal-Containing Polymer Hydrogels

Metal-containing polymer hydrogels have attracted increasing interest in recent years due to their outstanding properties such as biocompatibility, recoverability, self-healing, and/or redox activity. In this short review, methods for the preparation of metal-containing polymer hydrogels are introduced and an overview of these hydrogels with various functionalities is given. It is hoped that this short update can stimulate innovative ideas to promote the research of metal-containing hydrogels in the communities.

Cationic Metallo‐Polyelectrolytes for Robust Alkaline Anion‐Exchange Membranes

Chemically inert, mechanically tough, cationic metallo-polyelectrolytes were conceptualized and designed as durable anion-exchange membranes (AEMs). Ring-opening metathesis polymerization (ROMP) of cobaltocenium-containing cyclooctene with triazole as the only linker group, followed by backbone hydrogenation, led to a new class of AEMs with a polyethylene-like framework and alkaline-stable cobaltocenium cation for ion transport. These AEMs exhibited excellent thermal, chemical and mechanical stability, as well as high ion conductivity.

Charged Metallopolymer-Grafted Silica Nanoparticles for Antimicrobial Applications

Inappropriate and frequent use of antibiotics has led to the development of antibiotic-resistant bacteria, which cause infectious diseases that are difficult to treat. With the rising threat of antibiotic resistance, the need to develop effective new antimicrobial agents is prominent. We report antimicrobial metallopolymer nanoparticles, which were prepared by surface-initiated reversible addition-fragmentation chain transfer polymerization of a cobaltocenium-containing methacrylate monomer from silica nanoparticles. These particles are capable of forming a complex with β-lactam antibiotics, such as penicillin, rejuvenating the bactericidal activity of the antibiotic. Disk diffusion assays showed significantly increased antibacterial activities against both Gram-positive and Gram-negative bacteria. The improved efficiencies were attributed to the inhibition of hydrolysis of the β-lactam antibiotics and enhancement of local antibiotics concentration on a nanoparticle surface. In addition, hemolysis evaluations demonstrated minimal toxicity to red blood cells.

Trio Act of Boronolectin with Antibiotic-Metal Complexed Macromolecules toward Broad-Spectrum Antimicrobial Efficacy

Bacterial infections, particularly by Gram-negative pathogens, have become a serious threat to global healthcare due to the diminishing effectiveness of existing antibiotics. We report a nontraditional therapy to combine three components in one macromolecular system, in which boronic acid adheres to peptidoglycan or lipopolysaccharide via boron-polyol based boronolectin chemistry, cationic metal polymer frameworks interact with negatively charged cell membranes, and β-lactam antibiotics are reinstated with enhanced vitality to attack bacteria via evading the detrimental enzyme-catalyzed hydrolysis. These macromolecular systems exhibited high efficacy in combating pathogenic bacteria, especially Gram-negative strains, due to synergistic effects of multicomponents on interactions with bacterial cells. In vitro and in vivo cytotoxicity and hemolysis evaluation indicated that these multifunctional copolymers did not induce cell death by apoptosis, as well as did not alter the phenotypes of immune cells and did not show observable toxic effect on red blood cells.

Binding of Cobaltocenium-Containing Polyelectrolytes with Anionic Probes

Cationic cobaltocenium-containing polyelectrolytes have a unique ability to form ionic complex with various anionic species. We carried out two sets of model study to compare the relative binding strength of a cobaltocenium-containing polyelectrolyte. First, the nature and relative strength of intermolecular interaction between cobaltocenium-containing polyelectrolytes and different anionic probes were investigated by spectroscopic methods. A dye-displacement method was used to monitor absorbance and fluorescence emissions. Second, the binding strength of this cobaltocenium-containing polyelectrolyte was compared with a classical quaternary ammonium polymer. Formation of polyelectrolyte complex between the cobaltocenium-containing polyelectrolyte and a common anionic polyelectrolyte at various concentrations was examined by optical absorption and light scattering.Graphical Abstract

Recyclable magnetic nanoparticles grafted with antimicrobial metallopolymer-antibiotic bioconjugates

Over-prescription and improper use of antibiotics has led to the emergence of bacterial resistance, posing a major threat to public health. There has been significant interest in the development of alternative therapies and agents to combat antibiotic resistance. We report the preparation of recyclable magnetic iron oxide nanoparticles grafted with charged cobaltocenium-containing metallopolymers by surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization. β-Lactam antibiotics were then conjugated with metallopolymers to enhance their vitality against both Gram-positive and Gram-negative bacteria. The enhanced antibacterial activity was a result of synergy of antimicrobial segments that facilitate the inhibition of hydrolysis of antibiotics and local enhancement of antibiotic concentration on a nanoparticle surface. These magnetic nanoparticles can be recycled numerous times without losing the initial antimicrobial potency. Studies suggested negligible toxicity of metallopolymer-grafted nanoparticles to red blood cells and minimal tendency to induce resistance in bacteria.