Tuning of morphological and antibacterial properties of poly(3,4-ethylenedioxythiophene):peroxodisulfate by methyl violet

This study demonstrates a one-step synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) in the presence of the methyl violet (MV) dye. The structural properties of PEDOT:peroxodisulfate were studied using Raman and MALDI-TOF spectroscopies. The use of the MV dye in the polymerization process resulted in a change in the typical irregular morphology of PEDOT:peroxodisulfate, leading to the formation of spherical patterns. SEM and TEM analyses revealed that increasing the dye concentration can produce larger spherical aggregates probably due to the hydrophobic and π–π interactions. These larger aggregates hindered the charge transport and reduced the electrical conductivity. Interestingly, at higher dye concentrations (0.05 and 0.075 M), the PEDOT:peroxodisulfate/MV films exhibited significantly improved antibacterial activity against Staphylococcus aureus and Escherichia coli. Furthermore, the PEDOT:peroxodisulfate films with the incorporated MV dye exhibited a well-defined and repeatable redox behavior. The remarkable amalgamation of their optical, electrochemical and antibacterial properties provides the PEDOT:peroxodisulfate/MV materials with an immensely diverse spectrum of applications, including in optical sensors and medical devices.DKRVO, (RP/CPS/2022/001); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Akademie Věd České Republiky, AV ČR, (RVO 61389013

Processing and properties of polyethylene/montmorillonite nanocomposites

Polyethylene (PE) nanocomposite samples were prepared with Cloisite 25 A, 30B, and 93 A and Nanofil 5 and 3000 nanofillers. The amount of modified Na+ montmorillonite (MMT Na+) was fixed to 5 wt%. For the compounding of PE matrix and nanofillers, two different compounding equipments were used, KO Kneader Buss and APV twin-screw extruder. In all samples, maleic anhydride-modified PE (PEMa) was added as a compatibilizer. The content of PEMa in mixtures was always 5 wt%. The level of MMT exfoliation in the nanocomposite systems was studied by X-ray diffraction and by transmission electron microscopy observations. The properties of samples were evaluated by dynamical mechanical analysis (E* modulus at 30 degrees C) and by the measurement of tensile properties (stress and strain at break). Because of the possibility of usage of prepared materials in packaging industry, barrier properties were measured with focus on oxygen, carbon dioxide, and water vapor permeability. The influence of two different used compounding equipments on the prepared nanocomposite samples of PE nanocomposites was discussed

Preparation of Smart Surfaces Based on PNaSS@PEDOT Microspheres: Testing of E. coli Detection

The main task of the research is to acquire fundamental knowledge about the effect of polymer structure on the physicochemical properties of films. A novel meta-material that can be used in manufacturing sensor layers was developed as a model. At the first stage, poly(sodium 4-styrenesulfonate) (PNaSS) cross-linked microspheres are synthesized (which are based on strong polyelectrolytes containing sulfo groups in each monomer unit), and at the second stage, PNaSS@PEDOT microspheres are formed. The poly(3,4-ethylenedioxythiophene) (PEDOT) shell was obtained by the acid-assisted self-polymerization of the monomer; this process is biologically safe and thus suitable for biomedical applications. The suitability of electrochemical impedance spectroscopy for E. coli detection was tested; it was revealed that the attached bacterial wall was destroyed upon application of constant oxidation potential (higher than 0.5 V), which makes the PNaSS@PEDOT microsphere particles promising materials for the development of antifouling coatings. Furthermore, under open-circuit conditions, the walls of E. coli bacteria were not destroyed, which opens up the possibility of employing such meta-materials as sensor films. Scanning electron microscopy, X-ray photoelectron spectroscopy, water contact angle, and wide-angle X-ray diffraction methods were applied in order to characterize the PNaSS@PEDOT films

Biological properties of printable polyaniline and polyaniline–silver colloidal dispersions stabilized by gelatin

The oxidation of aniline with ammonium peroxydisulfate in the presence of gelatin yields spindle-like colloidal polyaniline particles having the particle size smaller than 200 nm. The similar oxidation of aniline with silver nitrate leads to hybrid composite polyaniline–silver nanoparticles with more complex morphology. The composites were characterized by transmission electron microscopy, dynamic light scattering and UV–vis spectroscopy. The cytoxicity of colloids has also been investigated. To test biointerface properties, the synthetized colloids were deposited to poly(ethylene terephthalate) foil using spiral bar coating and flexography printing technique. Prepared layers were tested for eukaryotic cell adhesion and proliferation, and antibacterial activity. The prepared surfaces do not only allow for eukaryotic cell adhesion and proliferation but also they possess significant antibacterial properties against Escherichia coli and Staphylococcus aureus, even without silver nanoparticles. This newly prepared surface has therefore high practical potential in variety of application in regenerative medicine or biosensing. © 2017 Elsevier B.V.14-05568P, GACR, Grantová Agentura České Republiky; 17-05095S, GACR, Grantová Agentura České RepublikyCzech Science Foundation [14-05568P, 17-05095S]; Ministry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504]; Technology Agency of the Czech Republic [TE01020022]; European Fund of the Regional Development [CZ.1.05/4.1.00/11.0251

Highly conducting and biocompatible polypyrrole/poly(vinyl alcohol) cryogels

Conducting macroporous soft cryogels were prepared by the oxidation of pyrrole within the frozen aqueous solutions of 5–8 wt.% poly(vinyl alcohol) at −24 °C. Mechanical properties of cryogels were independent of poly(vinyl alcohol) concentration, Young moduli were ≈20 kPa. The conductivity of compressed freeze-dried composites reached 18 S cm −1 thus exceeding the conductivity of polypyrrole alone. This level of conductivity was also preserved after long-term treatment with water, i.e. close to physiological conditions. In-vitro determined cytotoxicity demonstrated high potential applications due to low cytotoxicity. Moreover, compared to the steel based materials, the cryogels mimic the properties of soft tissues. All these properties are a prerequisite for the utilization in biomedical applications. © 2019 Elsevier B.V.Czech Science Foundation [17-05095S

Cationic Polymer-Coated Magnetic Nanoparticles with Antibacterial Properties: Synthesis and In Vitro Characterization

Uniformly sized magnetite nanoparticles (Dn = 16 nm) were prepared by a thermal decomposition of Fe(III) oleate in octadec-1-ene and stabilized by oleic acid. The particles were coated with Sipomer PAM-200 containing both phosphate and methacrylic groups available for the attachment to the iron oxide and at the same time enabling (co)polymerization of 2-(dimethylamino)ethyl methacrylate and/or 2-tert-butylaminoethyl methacrylate at two molar ratios. The poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) and poly[2-(dimethylamino)ethyl methacrylate-co-2-tert-butylaminoethyl methacrylate] [P(DMAEMA-TBAEMA)] polymers and the particles were characterized by 1H NMR spectroscopy, size-exclusion chromatography, transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, magnetometry, and ATR FTIR and atomic absorption spectroscopy. The antimicrobial effect of cationic polymer-coated magnetite nanoparticles tested on both Escherichia coli and Staphylococcus aureus bacteria was found to be time- and dose-responsive. The P(DMAEMA-TBAEMA)-coated magnetite particles possessed superior biocidal properties compared to those of P(DMAEMA)-coated one

Low-Melting Phosphate Glass Coatings for Structural Parts Composed of Depleted Uranium

The applications of depleted uranium in mechanical engineering are limited by its high susceptibility to corrosion. Among various methods of corrosion protection, painting is usually considered a fast and cost-efficient method; however, organic polymer paints are sensitive to ionizing radiation, which is a limiting factor, e.g., for the fabrication of shielding containers or structural parts. The solution presented in this work is the creation of a glassy inorganic layer on top of the depleted uranium surface. Zinc lead phosphate low-melting glass was investigated for this purpose. Glass frit was obtained as an amorphous solid, as confirmed by differential scanning calorimetry and X-ray diffraction. The frit was easily ground in liquid media down to sizes suitable for spraying onto the surface of depleted uranium. When the glass powder is sprayed onto the surface of a substrate and fired at 440 °C, a partially crystallized continuous film with a complex morphology is formed, which significantly inhibits corrosion. The coating material shows resistance against high doses of γ-irradiation

Multifunctional polypyrrole@maghemite@silver composites: synthesis, physico-chemical characterization and antibacterial properties

Maghemite (γ-Fe2O3) nanoparticles were synthesized by coprecipitation of ferrous and ferric salts with ammonia and oxidation with sodium hypochlorite. Polypyrrole (PPy) was obtained, by the chemical oxidative polymerization of pyrrole in an aqueous solution in the presence of iron oxide nanoparticles. The morphology of PPy was turned from globular to nanofibers by addition of dyes. The resulting PPy@γ-Fe2O3 hybrid composites were characterized by transmission electron microscopy, magnetic and electrical conductivity measurements and energy dispersive X-ray spectroscopy. Both the electrical conductivity and magnetic properties of the PPy@γ-Fe2O3 nanocomposites were controlled by the maghemite content due to the insulating properties of magnetic iron oxide nanoparticles added to the conducting polymer. Antibacterial activity of all materials was defined by determination of minimal inhibitory concentration. Antibacterial properties of native materials were improved by the reduction of silver ions from an aqueous solution to obtain PPy@γ-Fe2O3@silver composites. Due to the antibacterial properties of these composites, especially of those with silver particles, they can be considered for the applications where bacterial contamination can deteriorate the functionality of material. © 2018, Institute of Chemistry, Slovak Academy of Sciences.Czech Science Foundation [17-05095S]; TBU in Zlin [IGA/ CPS/2018/001

Polypyrrole-Barium Ferrite Magnetic Cryogels for Water Purification

Magnetic polypyrrole-gelatin-barium ferrite (PPy-G-BaFe) cryogels/aerogels were synthesized by one-step oxidative cryopolymerization of pyrrole in the presence of various fractions of barium ferrite (BaFe) nanoparticles, dispersed in aqueous gelatin solution. The successful incorporation of BaFe into the composites was confirmed by elemental analysis and scanning electron microscopy paired with an energy-dispersive X-ray detector. The maximum achieved content of BaFe in the resulting material was 3.9 wt%. The aerogels with incorporated BaFe had significantly higher specific surface area and conductivity, reaching 19.3 m2 g−1 and 4 × 10−4 S cm−1, respectively, compared to PPy-G aerogel, prepared in the absence of BaFe (7.3 m2 g−1 and 1 × 10−5 S cm−1). The model adsorption experiment using an anionic dye, Reactive Black 5, showed that magnetic PPy-G-BaFe aerogel, prepared at 10 wt% BaFe fraction, had significantly higher adsorption rate and higher adsorption capacity, compared to PPy-G (dye removal fraction 99.6% and 89.1%, respectively, after 23 h). Therefore, the prepared PPy-G-BaFe aerogels are attractive adsorbents for water purification due to their enhanced adsorption performance and the possibility of facilitated separation from solution by a magnetic field

Enhancement of conductivity, mechanical and biological properties of polyaniline-poly(N-vinylpyrrolidone) cryogels by phytic acid

Polyaniline-based cryogels were prepared by oxidative cryopolymerization in the presence of various concentrations of poly(N-vinylpyrrolidone) and phytic acid used as a polymer support and a dopant, respectively. Mechanical strength and handling stability of the resulting macroporous materials (pore size up to 70 μm) were significantly improved by the addition of poly(N-vinylpyrrolidone) into the polymerization system compared to the cryogels crosslinked only by phytic acid. Increase of poly(N-vinylpyrrolidone) concentration in the reaction medium above 5 wt%, while not noticeably changing mechanical properties, was found to lead to a decrease of conductivity and specific surface area. Introduction of optimal amount of phytic acid (0.2 M) as an additional codopant, in opposite, allowed enhancement of the material conductivity and specific surface area as well as increase of their tensile modulus. Polyaniline-poly(N-vinylpyrrolidone) cryogels containing phytic acid also showed better cytocompatibility due to lower cytotoxicity and improved cell adhesion and proliferation. © 2021 Elsevier LtdCzech Science FoundationGrant Agency of the Czech Republic [18-04669S, 19-16861S]; European Regional Development Fund (EFRE)European Commission; province of Upper Austria through the programme IWB 2014-2020Grantová Agentura České Republiky, GA ČR: 18-04669S, 19-16861S; European Regional Development Fund, FEDE