Effect of glycounits on the antimicrobial properties and toxicity behavior of polymers based on quaternized DMAEMA

Highly Efficient Antibacterial Surfaces Based on Bacterial/Cell Size Selective Microporous Supports

We report on the fabrication of efficient antibacterial substrates selective for bacteria, i.e., noncytotoxic against mammalian cells. The strategy proposed is based on the different size of bacteria (1-4 μm) in comparison with mammalian cells (above 20 μm) that permit the bacteria to enter in contact with the inner part of micrometer-sized pores where the antimicrobial functionality are placed. On the contrary, mammalian cells, larger in terms of size, remain at the top surface, thus reducing adverse cytotoxic effects and improving the biocompatibility of the substrates. For this purpose, we fabricated well-ordered functional microporous substrates (3-5 μm) using the breath figures approach that enabled the selective functionalization of the pore cavity, whereas the rest of the surface remained unaffected. Microporous surfaces were prepared from polymer blends comprising a homopolymer (i.e., polystyrene) and a block copolymer (either polystyrene-b-poly(dimethylaminoethyl methacrylate) (PDMAEMA) or a quaternized polystyrene-b-poly(dimethylaminoethyl methacrylate)). As a result, porous surfaces with a narrow size distribution and a clear enrichment of the PDMAEMA or the quaternized PDMAEMA block inside the pores were obtained that, in the case of the quaternized PDMAEMA, provided an excellent antimicrobial activity to the films.

Polymers for binding of the gram-positive oral pathogen Streptococcus mutans

Streptococcus mutans is the most significant pathogenic bacterium implicated in the formation of dental caries and, both directly and indirectly, has been associated with severe conditions such as multiple sclerosis, cerebrovascular and peripheral artery disease. Polymers able to selectively bind S. mutans and/or inhibit its adhesion to oral tissue in a non-lethal manner would offer possibilities for addressing pathogenicity without selecting for populations resistant against bactericidal agents. In the present work two libraries of 2-(dimethylamino)ethyl methacrylate (pDMAEMA)-based polymers were synthesized with various proportions of either N,N,N-trimethylethanaminium cationic- or sulfobetaine zwitterionic groups. These copolymers where initially tested as potential macromolecular ligands for S. mutans NCTC 10449, whilst Escherichia coli MG1655 was used as Gram-negative control bacteria. pDMAEMA-derived materials with high proportions of zwitterionic repeating units were found to be selective for S. mutans, in both isolated and S. mutans-E. coli mixed bacterial cultures. Fully sulfobetainized pDMAEMA was subsequently found to bind/cluster preferentially Gram-positive S. mutans and S. aureus compared to Gram negative E. coli and V. harveyi. A key initial stage of S. mutans pathogenesis involves a lectin-mediated adhesion to the tooth surface, thus the range of potential macromolecular ligands was further expanded by investigating two glycopolymers bearing α-mannopyranoside and β-galactopyranoside pendant units. Results with these polymers indicated that preferential binding to either S. mutans or E. coli can be obtained by modulating the glycosylation pattern of the chosen multivalent ligands without incurring unacceptable cytotoxicity in a model gastrointestinal cell line. Overall, our results allowed to identify a structure-property relationship for the potential antimicrobial polymers investigated, and suggest that preferential binding to Gram-positive S. mutans could be achieved by fine-tuning of the recognition elements in the polymer ligands.

Cytotoxicity and Antimicrobial Activity of Oral Rinses In Vitro

While oral rinses used for cosmetic purposes only do not necessarily have to be antiseptic, antimicrobial activity is required for medical indications, including oral and periodontal surgery. So the question arises—is the antimicrobial activity of oral rinses associated with any destructive changes in cell viability in vitro? To answer this question, we examined twelve oral rinses with respect to their antimicrobial and cytotoxic activity. Antimicrobial activity was screened against five bacterial strains using disc diffusion. Cytotoxicity was determined by mitochondrial reductase activity with primary gingival fibroblasts, L929 cells, and HSC-2 epithelial cells. Phase contrast microscopy and trypan blue staining were then performed to reveal cell morphology. Cells remained vital after exposure to oral rinses that were only used for cosmetic purposes. Moderate cytotoxic effects were observed for oral rinses containing 0.05% chlorhexidine, ethanol, or pegylated hydrogenated castor oil and sodium dodecyl sulfate. Other oral rinses containing 0.2% chlorhexidine and cocamidopropyl betaine exhibited strong cytotoxic and antimicrobial activity. Strong cytotoxic but moderate antimicrobial activity was observed in oral rinses containing cetylpyridinium chloride. The in vitro data show that oral rinses are heterogeneous with respect to their cytotoxic and antimicrobial effects. Based on their respective properties, oral rinses can be selected either to reduce the microbial load or for cosmetic purposes.

Antimicrobial and Hemolytic Studies of a Series of Polycations Bearing Quaternary Ammonium Moieties: Structural and Topological Effects

A series of polycations bearing quaternary ammonium moieties have shown antimicrobial activity against the Gram-negative bacterium Escherichia coli. Different polymer topologies governed by a disubstituted aromatic core as well as different diamine-based linkers were found to influence the antimicrobial properties. Moreover, the hemolytic activity against human red blood cells was measured and demonstrated good biocompatibility and selectivity of these polycations for bacteria over mammalian cells.

Rapid bactericidal activity of an amphiphilic polyacrylate terpolymer system comprised of same-centered comonomers with 2-carbon and 6-carbon spacer arms and an uncharged repeat unit

Cationic amphiphilic polyacrylate terpolymers with rapid bactericidal activity against E. coli and S. aureus.

Recyclable Escherichia coli-Specific-Killing AuNP-Polymer (ESKAP) Nanocomposites

Escherichia coli plays a crucial role in various inflammatory diseases and infections that pose significant threats to both human health and the global environment. Specifically inhibiting the growth of pathogenic E. coli is of great and urgent concern. By modifying gold nanoparticles (AuNPs) with both poly[2-(methacrylamido)glucopyranose] (pMAG) and poly[2-(methacryloyloxy)ethyl trimethylammonium iodide] (pMETAI), a novel recyclable E. coli-specific-killing AuNP-polymer (ESKAP) nanocomposite is proposed in this study, which based on both the high affinity of glycopolymers toward E. coli pili and the merits of antibacterial quaternized polymers attached to gold nanoparticles. The properties of nanocomposites with different ratios of pMAG to pMETAI grafted onto AuNPs are studied. With a pMAG:pMETAI feed ratio of 1:3, the nanocomposite appeared to specifically adhere to E. coli and highly inhibit the bacterial cells. After addition of mannose, which possesses higher affinity for the lectin on bacterial pili and has a competitive advantage over pMAG for adhesion to pili, the nanocomposite was able to escape from dead E. coli cells, becoming available for repeat use. The recycled nanocomposite retained good antibacterial activity for at least three cycles. Thus, this novel ESKAP nanocomposite is a promising, highly effective, and readily recyclable antibacterial agent that specifically kills E. coli. This nanocomposite has potential applications in biological sensing, biomedical diagnostics, biomedical imaging, drug delivery, and therapeutics.

Versatile Types of MRI-Visible Cationic Nanoparticles Involving Pullulan Polysaccharides for Multifunctional Gene Carriers

Owing to the low cytotoxicity and excellent biocompatibility, polysaccharides are good candidates for the development of promising biomaterials. In this paper, a series of magnetic resonance imaging (MRI)-visible cationic polymeric nanoparticles involving liver cell-targeting polysaccharides were flexibly designed for multifunctional gene delivery systems. The pullulan-based vector (PuPGEA) consisting of one liver cell-targeting pullulan backbone and ethanolamine-functionalized poly(glycidyl methacrylate) (denoted by BUCT-PGEA) side chains with abundant hydroxyl units and secondary amine was first prepared by atom transfer radical polymerization. The resultant cationic nanoparticles (PuPGEA-GdL or PuPGEA-GdW) with MRI functions were produced accordingly by assembling PuPGEA with aminophenylboronic acid-modified Gd-DTPA (GdL) or GdW10O36(9-) (GdW) via the corresponding etherification or electrostatic interaction. The properties of the PuPGEA-GdL and PuPGEA-GdW nanoparticles including pDNA condensation ability, cytotoxicity, gene transfection, cellular uptake, and in vitro and in vivo MRI were characterized in details. Such kinds of cationic nanoparticles exhibited good performances in gene transfection in liver cells. PuPGEA-GdW demonstrated much better MRI abilities. The present design of PuPGEA-based cationic nanoparticles with the liver cell-targeting polysaccharides and MRI contrast agents would shed light on the exploration of tumor-targetable multifunctional gene delivery systems.

Synthesis of antimicrobial block copolymers bearing immobilized bacteriostatic groups

Antimicrobial block copolymers bearing covalently bonded quaternized ammonium groups were synthesized through atom transfer radical polymerization (ATRP). Moreover, a new class of antimicrobial block copolymers were designed combining two types of biocide incorporation into one system (both contact-based and release-based mechanisms).

Polymeric drugs: Advances in the development of pharmacologically active polymers

Synthetic polymers play a critical role in pharmaceutical discovery and development. Current research and applications of pharmaceutical polymers are mainly focused on their functions as excipients and inert carriers of other pharmacologically active agents. This review article surveys recent advances in alternative pharmaceutical use of polymers as pharmacologically active agents known as polymeric drugs. Emphasis is placed on the benefits of polymeric drugs that are associated with their macromolecular character and their ability to explore biologically relevant multivalency processes. We discuss the main therapeutic uses of polymeric drugs as sequestrants, antimicrobials, antivirals, and anticancer and anti-inflammatory agents.

Antimicrobial polymeric materials with quaternary ammonium and phosphonium salts

Polymeric materials containing quaternary ammonium and/or phosphonium salts have been extensively studied and applied to a variety of antimicrobial-relevant areas. With various architectures, polymeric quaternary ammonium/phosphonium salts were prepared using different approaches, exhibiting different antimicrobial activities and potential applications. This review focuses on the state of the art of antimicrobial polymers with quaternary ammonium/phosphonium salts. In particular, it discusses the structure and synthesis method, mechanisms of antimicrobial action, and the comparison of antimicrobial performance between these two kinds of polymers.

Functional surfaces obtained from emulsion polymerization using antimicrobial glycosylated block copolymers as surfactants

Antimicrobial surfaces were obtained from latex particles stabilized with amphiphilic block copolymer surfactants containing both quaternary ammonium and carbohydrate groups.

Quaternized poly(2-(dimethylamino)ethyl methacrylate)-grafted agarose copolymers for multipurpose antibacterial applications

Polymeric quaternary ammonium salts-functionalized agarose not only exhibit good antibacterial activity in solution form, but also can be solidified to construct antibacterial surfaces.