In the present work, alginate-based mats with and without ZnO nanoparticles were prepared via an electrospinning technique and subjected to a washing-cross-linking process to obtain highly stable products characterized by thin and homogeneous nanofibers with a diameter of 100 ± 30 nm. Using a commercial collagen product as control, the biological response of the prepared mats was carefully evaluated with particular attention paid to the influence of the used cross-linking agent (Ca2+, Sr2+, or Ba2+ ions) and to the presence of nanofillers. Fibroblast and keratinocyte cultures successfully proved the safety of the prepared alginate-based mats, whereas ZnO nanoparticles were found to provide strong antibacteriostatic and antibacterial properties; above all, the strontium- and barium-cross-linked samples showed performances in terms of cell adhesion and growth very similar to those of the commercial collagen membrane despite them showing a significantly lower protein adsorption. Moreover, the mechanical and water-related properties of the strontium-cross-linked mats embedding ZnO nanoparticles were proven to be similar to those of human skin (i.e., Young modulus of 470 MPa and water vapor permeability of 3.8 × 10–12 g/m Pa s), thus proving the ability of the prepared mats to be able to endure considerable stress, maintaining at the same time the fundamental ability to remove exudates. Taking into account the obtained results, the proposed alginate-based products could lead to harmless and affordable surgical patches and wound dressing membranes with a simpler and safer production procedure than the commonly employed animal collagen-derived systems.

We report on the growth and characterization of onedimensional\ud (1D) planar all-polymer photonic crystals (PhC) with\ud high dielectric contrast (Dn50.3) prepared by spin coating using\ud hyperbranched polyvinylsulfide polymers (HB-PVS) as high\ud refractive index material and cellulose acetate as low refractive\ud index material. Solution processable HB-PVS show a near ultraviolet\ud absorption inducing an increased refractive index in the\ud visible-near infrared (n51.68, k51000 nm). HBPVS:Cellulose\ud Acetate Distributed Bragg Reflectors show a very clear fingerprint\ud of the photonic band gap possessing the expected polarized\ud dispersion properties as a function of the incidence angle.\ud Moreover, engineered microcavities tuned on the weak fluorescence\ud spectrum of the HB-PVS show directional fluorescence\ud enhancement effects due to spectral redistribution of the emission\ud oscillator strength. The combination of all these properties\ud testifies the high optical quality of the obtained photonic structures\ud thus indicating HB-PVS as an interesting material for the\ud preparation of such PhC. V

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The solution properties of a novel soluble polydiacetylene, poly[1,6-bis(3,6-dihexadecyl-9H-carbazol-9-yl)hexa-\ud 2,4-diyne] (polyDCHD-HS), have been investigated by using UV–Vis absorption, fluorescence, and FT-Raman\ud spectroscopies. The polymer gives rise to stable, brilliant red solutions in aromatic solvents and in chloroform at\ud room temperature with no evidence of the colour transition to yellow that usually takes place by increasing the\ud temperature with other soluble polydiacetylenes. A particular role appears to be played by benzene–polyDCHD-HS\ud interactions, because in this solvent a very narrow and intense excitonic peak is observed at room temperature in the\ud electronic spectrum. Interestingly, these solutions show also a well-resolved fluorescence spectrum, with a very small\ud Stokes shift and a rather high quantum yield (≅102). Furthermore, a very efficient transfer of the excitation energy\ud from the carbazolyl substituents to the conjugated backbone is found to take place. On account of the observation\ud that by increasing the temperature of the benzene solutions up to 75 C the excitonic feature in both the absorption\ud and the emission spectra undergoes fully reversible broadening and intensity reduction accompanied by the increase\ud of the Stokes shift, without any dramatic colour change, it is likely that the rates of torsional motions in the polymer\ud chains are thermally activated without modifying the average conjugation length of the polymer chains. FT-Raman\ud measurements in benzene solutions in the same temperature range have confirmed this conclusion. The photophysical\ud properties of polyDCHD-HS in benzene around 60 C are quite similar to those observed in other aromatic solvents\ud at room temperature. By heating up the red solutions in toluene or in chlorobenzene, no spectral shift is observed but\ud only a limited increase of the absorption band broadening. All these findings strongly suggest that by the appropriate\ud choice of the substituents it is possible to obtain stable solutions of the red form of polydiacetylenes

A multilayer nanofibrous membrane consisting of a layer of polycaprolactone and one of physically cross-linked alginate-embedding ZnO nanoparticles is prepared via electrospinning technique as potential wound healing patches with drug delivery capabilities. A washing–cross-linking protocol is developed to obtain stable materials at the same time removing poly(ethylene oxide), which was used here as a cospinning agent for alginate, without interfering with the membrane’s peculiar nanofibrous structure. The mechanical behavior of the samples is assessed via a uniaxial tensile test showing appropriate resistance and manageability together with a good thermal stability as proved via thermogravimetric analysis. The polycaprolactone external layer enriches the samples with good liquid-repellent properties, whereas the alginate layer is able to promote tissue regeneration owing to its capability to promote cell viability and allow exudate removal and gas exchanges. Moreover, using methylene blue and methyl orange as model molecules, promising drug delivery abilities are observed for the mats. Indeed, depending on the nature and on the dye-loading concentration, the release kinetic can be easily tuned to obtain a slow controlled or a fast burst release. Consequently, the proposed alginate–polycaprolactone membrane represents a promising class of innovative, simple, and cost-effective wound healing patches appropriate for large-scale production.