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A new synthetic approach is presented for the preparation of Poly(N-isopropylacrylamide-block-styrene) PNIPAM-b-PS via an Atom Transfer Radical Polymerization (ATRP) technique. The proposed method is based on application of 2-chloro-N-(2-hydroxyethyl)propanamide (NCPAE) as a bifunctional initiator, which enables ATRP of two monomers, differing in activity and polarity, into two stages. The synthesized copolymer molecules contain two well-defined polymer chains connected by a linker, which is a derivative of the proposed initiator. Using NCPAE led to PNIPAMs with well-planned molecular weight, low polydispersities (PDI=1.1÷1.3) and hydroxyl functionality. Activation of such blocks for initiation of styrene polymerization was performed using α-bromoisobutyryl bromide. After such a modification, the synthesized homopolymers acted as macroinitiators in ARGET ATRP and a well-defined polystyrene block, as the next one in the polymer chain was successfully formed. Both of the synthesized macromolecules, PNIPAM and PNIPAM-b-PS, exhibit a thermoresponsive behavior with explicit lower critical solution temperatures (LCST) in their aqueous solutions. The synthesized homopolymers and subsequently derived block copolymers were characterized using Size-Exclusion Chromatography, Differential Scanning Calorimetry, Dynamic Light Scattering, and NMR spectroscopy.

Purpose Periodontal disease (PD), defined as oral inflammation caused by dental plaque, is an emerging problem. PD may lead to tooth loss, and treatment options are limited. In this study, we designed, synthesized, and characterized silver nanoparticles (AgNPs) conjugated with chlorhexidine (AgNPs-CHL) or metronidazole (AgNPs-PEG-MET) to determine whether they can be used to treat PDs. Materials and Methods AgNPs were synthesized and characterized by transmission electron microscopy, UV-vis spectrometry, thermogravimetric analyses, and dynamic light scattering. We determined the safety and the antimicrobial and anti-inflammatory properties of synthesized AgNPs in an in vitro model of periodontitis. Antimicrobial properties were determined by measuring the minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) on reference strains of bacteria and fungi. Human gingival fibroblast (HGF-1), murine macrophage (RAW264.7) and human foetal osteoblast (hFOB1.19) cells were used in the study. Lipopolysaccharide (LPS) was used to induce inflammation. Cytokine levels were measured using an enzyme-linked immunosorbent assay; metalloproteinase expression was measured using Western blotting. Results The synthesized AgNPs were spherical and narrow-dispersed with an average diameter of 13.4 nm ± 3.0 nm in the case of AgNPs-CHL and 3.72 nm ± 0.72 nm in the case of AgNPs-PEG-MET. Both types of AgNPs were active against bacteria and fungi. AgNPs-CHL proved to be a more potent antimicrobial agent, although they were more cytotoxic than AgNPs-PEG-MET; however, both demonstrated beneficial properties in nontoxic concentrations. AgNPs-CHL and AgNPs-PEG-MET decreased the production of proinflammatory cytokines IL-1β, IL-6, IL-8 and TNFα. Both agents also decreased the levels of metalloproteinases MMP3 and MMP8, which may indicate that they will inhibit tissue degradation. Conclusion AgNPs-CHL and AgNPs-PEG-MET may be possible therapeutic options for PD, as they have antibacterial and anti-inflammatory properties. However, to fully understand the potential of AgNPs, our in vitro findings must be evaluated in an in vivo model.

The selective oxidation of alcohols, leading to appropriate aldehydes, is widely recognised as one of the most important reactions in organic synthesis. With ever-increasing environmental concerns, much attention has been directed toward developing catalytic protocols that use molecular oxygen as an oxidant. An ideal green oxidation process should employ a highly active, selective and recyclable catalyst that can work with oxygen under mild conditions. This paper presents a successful application of densely grafted silver nanostructures with stable nitroxide radicals (N-AgNPs) as an effective, easily-recovered and regenerable catalyst for the selective oxidation of alcohols. The fabricated ultra-small and narrow dispersive silver nanoparticles have been fully characterised using physicochemical methods (TEM, DLS, XPS, TGA). N-AgNPs have been successfully applied to oxidise several model alcohols: benzyl alcohol, 4-pyridinemethanol, furfuryl alcohol, 1-phenyl ethanol, n-heptanol and allyl alcohol under mild conditions using oxygen as a stoichiometric oxidant. Notably, the fabricated nitroxide grafted silver nanoparticles (N-AgNPs) were reused more than ten times in the oxidation of a series of primary alcohols to corresponding aldehydes under mild conditions with very high yields and a selectivity close to 100%.

Here, we report our studies on photoresponsive poly(meth)acrylates containing azobenzene groups connected to a polymer backbone via a short methylene linker. A series of side-chain azobenzene polymers was synthesized via the atom transfer radical polymerization (ATRP) technique using several catalytic systems. The polymers synthesized under the optimized conditions were characterized by a narrow polydispersity (Đ ≤ 1.35), and they underwent a reversible transformation of their structure under light illumination. The fabricated polymers can store and release energy accumulated during the UV-light illumination by the thermal cis-trans isomerization of the chromophore groups. The enthalpy of the process (determined from DSC) was relatively high and equaled 61.9 J∙g−1 (17 Wh∙kg−1), indicating a high potential of these materials in energy storage applications. The liquid-crystalline behavior of the synthesized poly(meth)acrylates was demonstrated by the birefringent optical textures as observed in thin-films and X-ray scattering studies.