Composites of cobalt ferrite nanoparticles in a polypyrrole (PPy) matrix have been synthesized in acid media and characterized by X‐ray diffraction studies, scanning and transmission electron microscopy observation, thermogravimetric analysis, conductivity, and infrared spectroscopy measurements. Two types of composites were prepared: one including dodecylbenzenesulphonic acid as a particle protector and another one without protection. The magnetic behavior was studied through DC magnetization measurements; hysteresis loops were observed, showing ferromagnetic behavior for particles and composites. Materials with particle protection showed magnetic parameters independent of the PPy/ferrite ratio; in the absence of protector, both the coercivity and remanence ratio decreased as the PPy/ferrite ratio increased. These results are attributed to conducting polymer effects on the ferrite particles, affecting the magnetic anisotropy. On the other hand, composites with low PPy/ferrite ratio showed positive magnetoresistance of up to 20% at room temperature, indicating an effect of the magnetic particles on polymer conduction. POLYM. COMPOS., 39:4617–4627, 2018. © 2017 Society of Plastics Engineers

The gelation properties and mode of self-assembly of six asymmetrical hexaether triphenylene derivatives mono-functionalized with carboxylic and primary amine groups were investigated. The presence of a carboxylic and amine group attached to the triphenylene core generated stable, thermo- and pH-sensitive supramolecular π-organogels with a reversible response to both stimuli. In order to understand the gelation process, we studied the effect of the spacer length and found a different gelation scope for the acid and basic derivatives that accounts for a different supramolecular self-assembly. The presence of the basic group on the amino derivatives was used to guide and catalyze the templated in situ sol-gel polymerization of TEOS and allowed us, under controlled hydrolytic conditions, to prepare an entangled fibrillar network of silica nanotubes.

Three new photoactive polymeric materials embedding a hexanuclear molybdenum cluster (Bu4N)2[Mo6I8(CH3COO)6] (1) have been synthesized and characterized by means of Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and emission spectroscopy. The materials are obtained in the format of transparent and thin sheets, and the formulations used to synthesize them are comprised of 2-hydroxyethyl methacrylate (HEMA), as a polymerizable monomer, and ethylene glycol dimethacrylate (EGDMA) or poly­(ethylene glycol)­dimethacrylate (PEGDMA), as cross-linkers. All the polymeric hydrogels generate singlet oxygen (1O2) upon irradiation with visible light (400–700 nm), as demonstrated by the reactivity toward two chemical traps of this reactive species (9,10-dimethylanthracene and 1,5-dihydroxynaphthalene). Some differences have been detected between the photoactive materials, probably attributable to variations in the permeability to solvent and oxygen. Notably, one of the materials resisted up to 10 cycles of photocatalytic oxygenation reactions of 1,5-dihydroxynaphthalene. All three of the polyHEMA hydrogels doped with 1 are efficient against S. aureus biofilms when irradiated with blue light (460 nm). The material made with the composition of 90% HEMA and 10% PEGDMA (Mo6@polymer-III) is especially easy to handle, because of its flexibility, and it achieves a notable level of bacterial population reduction (3.0 log10 CFU/cm2). The embedding of 1 in cross-linked polyHEMA sheets affords a protective environment to the photosensitizer against aqueous degradation while preserving the photochemical and photobactericidal activity.

Two new photoactive materials have been prepared, characterized and tested against Pseudomonas aeruginosa bacteria (planktonic suspension). The synthesis of the polymeric photosensitizers can be made at a multigram scale, in few minutes, starting from inexpensive and readily available materials, such as Rose Bengal (photosensitizer) and ion exchange resins Amberlite ® IRA 900 (macroporous) or IRA 400 (gel-type) as cationic polystyrene supports. The most notable feature of these systems is their notable bactericidal activity in the dark (4-5 log10 CFU / mL reduction of the population of P. aeruginosa) which becomes enhanced upon irradiation with visible light (to reach a total reduction of 8 log10 CFU / mL for the macroporous polymer at a fluence of 120 J/cm 2 using green light of 515 nm).

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Four formulations have been used to produce different poly(2-hydroxyethyl methacrylate) (PHEMA) thin films, containing singlet oxygen photosensitizer Rose Bengal (RB). The polymers have been characterized employing Thermogravimetric Analysis (TGA), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and UV-vis Absorption Spectroscopy. When irradiated with white light (400–700 nm) films generated singlet oxygen (1O2), as demonstrated by the reactivity with 1O2 trap 9,10-dimethylanthracene (DMA). Material with the highest RB loading (polymer A4, 835 nmol RB/g polymer) was able to perform up to ten cycles of DMA oxygenation reactions at high conversion rates (ca. 90%). Polymer A4 was also able to produce the complete eradication of a Pseudomonas aeruginosa planktonic suspension of 8 log10 CFU/mL, when irradiated with white light (total dose 72 J/cm2). The antimicrobial photodynamic effect was remarkably enhanced by adding potassium iodide (100 mM). In such conditions the complete bacterial reduction occurred with a total light dose of 24 J/cm2. Triiodide anion (I3−) generation was confirmed by UV-vis absorption spectroscopy. This species was detected inside the PHEMA films after irradiation and at concentrations ca. 1 M. The generation of this species and its retention in the matrix imparts long-lasting bactericidal effects to the RB@PHEMA polymeric hydrogels. The polymers here described could find potential applications in the medical context, when optimized for their use in everyday objects, helping to prevent bacterial contagion by contact with surfaces.

The first report of a family of styrylpyrylium dyes acting on mitochondria in a theranostic way.