Antimicrobial Activity of Hybrid Nanomaterials Based on Star and Linear Polymers of N,N'-Dimethylaminoethyl Methacrylate with In Situ Produced Silver Nanoparticles

Quaternized Poly(N,N'-dimethylaminoethyl methacrylate) Star Nanostructures in the Solution and on the Surface

Antibacterial polymeric materials are promising in the fight against resistant bacteria strains. Amongst them, cationic macromolecules with quaternary ammonium groups are one of intensively studied, as they interact with the bacterial membranes causing cell death. In this work, we propose to use nanostructures composed of polycations with star topology for the preparation of antibacterial materials. First, star polymers of N,N'-dimethylaminoethyl methacrylate and hydroxyl-bearing oligo(ethylene glycol) methacrylate P(DMAEMA-co-OEGMA-OH) were quaternized with various bromoalkanes and their solution behavior was studied. It was shown that in water two modes of star nanoparticles were observed, of diameters about 30 nm and up to 125 nm, independently of the quaternizing agent. Separately layers of P(DMAEMA-co-OEGMA-OH) stars were obtained. In this case, the chemical grafting of polymers to the silicon wafers modified with imidazole derivatives was applied, followed by the quaternization of the amino groups of polycations. A comparison of the quaternary reaction in solution and on the surface showed that in the solution it is influenced by the alkyl chain length of the quaternary agent, while on the surface such relationship is not observed. After physico-chemical characterization of the obtained nanolayers, their biocidal activity was tested against two strains of bacteria E. coli and B. subtilis. The best antibacterial properties exhibited layers quaternized with shorter alkyl bromide, where 100% growth inhibition of E. coli and B. subtilis after 24 h of contact was observed.

Swelling and Viscoelastic Properties of Cellulose-Based Hydrogels Prepared by Free Radical Polymerization of Dimethylaminoethyl Methacrylate in Cellulose Solution

The grafting of a stimuli-responsive polymer (poly(dimethylaminoethyl methacrylate)) onto cellulose was achieved by performing free radical polymerization of a vinyl/divinyl monomer in cellulose solution. The grafting and crosslinking efficiency in the material have been increased by subsequent irradiation of the samples with ionizing radiation (doses of 10, 30, or 100 kGy). The relative amount of poly(dimethylaminoethyl methacrylate) in the prepared hydrogels was determined by infrared spectroscopy. The swelling behavior of the hydrogels was studied thoroughly, including microgelation extent, equilibrium swelling, and reswelling degree, as well as the dependence on the gelation procedure. The dynamic viscoelastic behavior of prepared hydrogels was also studied. The tan δ values indicate a solid-like behavior while the obtained hydrogels have a complex modulus in the range of 14-39 kPa, which is suitable for hydrogels used in biomedical applications. In addition, the incorporation of Ag particles and the adsorption of Fe³⁺ ions were tested to evaluate the additional functionalities of the prepared hydrogels. It was found that the introduction of PDMAEMA to the hydrogels enhanced their ability to synthesize Ag particles and absorb Fe³⁺ ions, providing a platform for the potential preparation of hydrogels for the treatment of wounds.

Hybrid nanolayers of star polymers and silver nanoparticles with antibacterial activity

The aim of this study was to obtain stable star polymer layers with incorporated silver nanoparticles (AgNPs) and to study the antimicrobial activity of these hybrid materials. In this work, a novel approach regarding the synthesis of AgNPs directly by the star polymer layer is presented. Nanolayers of poly(N,N'-dimethylaminoethyl methacrylate) and hydroxyl-bearing poly[oligo(ethylene glycol) methacrylate] (P(DMAEMA-co-OEGMA-OH)) stars, covalently bound with solid supports, were obtained through chemical reaction of hydroxyl groups in the star arms with substrate modified with imidazole derivative. Quantitative chemical composition analysis and tracking of the changes in the morphology and wettability after every step of surface modification confirmed the covalent attachment of stars with the support. In the next step, the polymer nanolayers were modified with AgNPs formed in situ using only amine groups of the star arms and followed by the crystal quartz microbalance (QCM). The analysis of the layer thickness and affinity to water, both with the shape, size and amount of silver incorporated into the layer, confirmed the efficacy of AgNPs formation. The amount of silver incorporated into layers was correlated with the molar masses of the grafted stars, and a possible location of AgNPs within layers was shown. The antibacterial activity tests of prepared nanolayers showed that obtained hybrid materials were highly effective against both gram-positive and gram-negative bacteria strains. This study shows that the obtained layers are promising as stable coatings for antibacterial applications.

Antibacterial and cytotoxic properties of star-shaped quaternary ammonium-functionalized polymers with different pendant groups

The correlation between the structure and biological activity of polymers is critically important for rationally designing effective antibacterial polymers. Here, the antibacterial activity, cytotoxicity, and selectivity of structurally well-defined, star-shaped...

The Role of Polymer Structure in Formation of Various Nano- and Microstructural Materials: 30 Years of Research in the Laboratory of Nano- and Microstructural Materials at the Centre of Polymer and Carbon Materials PAS

The review summarizes the research carried out in the Laboratory of Nano- and Microstructural Materials at the Centre of Polymer and Carbon Materials, Polish Academy of Sciences (CMPW PAS). Studies carried out for many years under the guidance of Professor Andrzej Dworak led to the development and exploration of the mechanisms of oxirane and cyclic imine polymerization and controlled radical polymerization of methacrylate monomers. Based on that knowledge, within the last three decades, macromolecules with the desired composition, molar mass and topology were obtained and investigated. The ability to control the structure of the synthesized polymers turned out to be important, as it provided a way to tailor the physiochemical properties of the materials to their specific uses. Many linear polymers and copolymers as well as macromolecules with branched, star, dendritic and hyperbranched architectures were synthesized. Thanks to the applied controlled polymerization techniques, it was possible to obtain hydrophilic, hydrophobic, amphiphilic and stimulus-sensitive polymers. These tailor-made polymers with controlled properties were used for the construction of various types of materials, primarily on the micro- and nanoscales, with a wide range of possible applications, mainly in biomedicine. The diverse topology of polymers, and thus their properties, made it possible to obtain various types of polymeric nanostructures and use them as nanocarriers by encapsulation of biologically active substances. Additionally, polymer layers were obtained with features useful in medicine, particularly regenerative medicine and tissue engineering.

Hybrid Polydopamine/Ag Shell-Encapsulated Magnetic Fe3O4 Nanosphere with High Antibacterial Activity

The bacteria, which usually contaminate water environment, often cause terrible infectious diseases thus seriously threaten people's health. To meet the increasing requirement of the public health care, an easily separable nanomaterial with sustainable anti-bacteria performance is required. This work reports a Fe₃O₄@PDA/Ag/PDA core-shell nanosphere in which the Ag nanocrystals immobilized on the magnetic carrier are protected by an external polydopamine (PDA) layer. The magnetic hybrid nanospheres are constructed by a tunable coating method and the particle parameters can be effectively controlled by the experimental condition. The antibacterial potential of the nanospheres is evaluable by using the Staphylococcus aureus and Escherichia coli as the models. The results indicate the Fe₃O₄@PDA/Ag/PDA core-shell nanospheres have a high antibacterial performance by measuring the minimum inhibitory concentration and the minimum bactericidal concentration. Finally, the product is expected to have a sustainable activity because the protecting PDA layer reduce the releasing rate of the Ag⁺ ions and the materials can be magnetically recovered from the media after the disinfection procedure.