The effect of converting ammonium into guanidine moieties, compared to other factors such as molecular weight or hydrophobicity, on the antibacterial activity is investigated for homo- and copolymers of 2-aminoethylmethacrylate in solution or coatings. Polymers are obtained by free radical polymerization, polymer-analogous guanidinylation is conducted with cyanamide; non-leaching immobilization is achieved by LBL assembly of homopolymers or crosslinking of functional sidegroups in copolymers. Antibacterial activity to Escherichia coli or Bacillus subtilis is determined by different standard methods. Guanidinylation improves antibacterial activity and speed as well as cytotoxicity of hydrophilic homo- and copolymers in solution or coatings.
Electrospun ionic nonwovens are obtained by green electrospinning of aqueous dispersions. The resulting nonwovens are termed as chameleon nonwovens since their surface properties can be tailored in a large variety by coating of different functionalities following the protocol of the layer-bylayer process (LBL). The dimensional stability of the electrospun fi bers in the chameleon nonwovens is achieved by photo-cross-linking after electrospinning and thereby overcoming the repulsive forces of the ionic moieties in the fi bers. Depending on the nature of the ionic moieties different materials are coated by LBL including dyes, antibacterial materials, silver, and gold nanoparticles. Enhanced coating effi ciency for coating of metal nanoparticles is observed when the chameleon nonwovens were precoated by a polyelectrolyte.
A novel type of elastomers with silver nanoparticles (AgNP) as cross-linkers has been obtained by a quantitative one-phase bottom-up procedure based on α,ω-dimercapto-poly(cis-1,4-isoprene) (PIP). This telechelic polymer with high cis-content of >80% and near-quantitative functionalization degree has been synthesized in a one-pot procedure by anionic polymerization. It was cross-linked by coordination of the thiol groups to in-situ synthesized AgNP to yield a repeatedly melt-processable elastomer. It was found that the E-modulus increased up to an ideal ratio of AgNP to PIP and decreases drastically with AgNP oversaturation due to decreasing cross-linking density. Swelling experiments were in agreement with these results. The cross-linking of telechelic polymers with metal nanoparticles has been applied to other metals and polymers, leading to cross-linked materials in all cases. Antibacterial properties of the silver-containing elastomers were found by the Kirby–Bauer test.
Alkyloxyethylammonium ionenes are reported as biocompatible biocides with a time of biocidal action within a few minutes. The presence of both ethoxyethyl and aliphatic spacers besides long alkyl chain substituents on the quaternary nitrogen atom differentiates these biocides structurally from the known polyionenes. The influence of alkyl spacer length, counter ion and length of the pendant alkyl groups on the antibacterial properties is studied. E. coli is adopted as a test organism. MIC and MBC values are determined via broth dilution methods; time-dependent tests are accomplished by determining the number of viable cells with the spread-plate method after different contact times. Structural characterization is conducted via NMR and mass spectrometry techniques.
Novel degradable and antibacterial polycaprolactone-based polymers are reported in this work. The polyesters with pendent propargyl groups are successfully prepared by ring-opening polymerization and subsequently used to graft antibacterial hydantoin moieties via click chemistry by a copper(I)-catalyzed azide-alkyne cycloaddition reaction. The well-controlled chemical structures of the grafted copolymers and its precursors are verified by FT-IR spectroscopy, NMR spectroscopy, and GPC characterizations. According to the DSC and XRD results, the polymorphisms of these grafted copolymers are mostly changed from semicrystalline to amorphous depending on the amount of grafted hydantoin. Antibacterial assays are carried out with Bacillus subtilis and two strains of Escherichia coli and show fast antibacterial action.
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