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Study of macromolecular structure and dynamics of networks formed by pulsed electron-beam irradiation of poly(N-vinyl pyrrolidone) (PVP) aqueous solutions, at relatively low energy per pulse and across different concentration regimes, provides the basis for the understanding of a new generation of functional nanostructures. Networks are the result of the follow-up reactions initiated by a continuous series of electron pulse-generated hydroxyl radicals, which may have a different fate at the variance of polymer concentration. Different spectroscopic techniques, FT-IR, 13C {1H} CP-MAS NMR and Raman, applied to characterize the formed networks, describe a profound modification of the chemical structure when network size is approaching the nanoscale. Static light scattering measurements provide further information on the average weight molecular weight modification of PVP when forming nanogel particles. From the simultaneous control of network size and modification of chemical functionality stems also an intrinsic fluorescence of these nanogels never observed before. Altogether the obtained radiation-sculptured nanogels exhibit interesting multifunctionality that, coupled with the already proven biocompatibility, can be exploited in the biomedical field.

Responsive hydrogels filling the interstitial spaces of photonic crystals can form mesoscopically structured materials, which exhibit reversible shifts in the Bragg diffracted light as a response of environmental changes. These materials can be used to generate chemical or biochemical sensors. The present work reports on the synthesis and characterization of ethanol responsive hydrogels that can be used in the design of novel breathalyzers. The dynamic mechanical behavior of the macroscopic hydrogels and their swelling features in the presence of different liquids or vapors have been investigated to orientate the choice of the best responsive material and curing process. The swelling behavior of a selected hydrogel embedding the photonic crystal made of polystyrene nanoparticles as function of the concentration of ethanol vapor was studied through UV–Vis optical transmission spectroscopy and compared to the behavior of the macrogel analogue.

Poly(N-vinylpyrrolidone)-grafted-acrylic acid biocompatible nanogels (NGs) were prepared using an exiting industrial-type electron accelerator and setups, starting from semi-dilute aqueous solutions of a commercial PVP and the acrylic acid monomer. As a result, NGs with tunable size and structure can be obtained quantitatively. Sterility was also imparted at the integrated dose absorbed. The chemical structure of the NGs produced was confirmed through Fourier Transformer Infrared Spectroscopy (FT-IR). The molecular and physico-chemical properties of NGs, such as the hydrodynamic dimensions and surface charge densities, for various polymer and monomer concentrations in the irradiated solutions, are discussed here.

Study of macromolecular structure and dynamics of networks formed by pulsed electron-beam irradiation of poly(N-vinyl pyrrolidone) (PVP) aqueous solutions, at relatively low energy per pulse and across different concentration regimes, provides the basis for the understanding of a new generation of functional nanostructures. Networks are the result of the follow–up reactions initiated by a continuous series of electron pulse-generated hydroxyl radicals, which may have a different fate at the variance of polymer concentration. Different spectroscopic techniques, FT-IR, 13 C { 1 H} CP-MAS NMR and Raman, applied to characterize the formed networks, describe a profound modification of the chemical structure when network size is approaching the nanoscale. Static light scattering measurements provide further information on the average weight molecular weight modification of PVP when forming nanogel particles. From the simultaneous control of network size and modification of chemical functionality stems also an intrinsic fluorescence of these nanogels never observed before. Altogether the obtained radiation-sculptured nanogels exhibit interesting multifunctionality that, coupled with the already proven biocompatibility, can be exploited in the biomedical field.

Radiation-engineered poly(N-vinyl pyrrolidone) nanogels are very interesting biocompatible nanocarriers for i.v. administration of therapeutics and contrast agents for bioimaging among other applications. Nanogels are usually produced upon irradiation of dilute aqueous polymer solutions. Under these conditions, the polymer radicals formed primarily react via intramolecular radical-radical combination forming intramolecular crosslinks. The manufacturing process is fast and effective and grants excellent control of particle size and simultaneous sterilization of the formed nanogels. Interestingly, primary amino groups and carboxyl groups, useful for (bio)conjugation, are also formed in a dose-dependent fashion when manufacturing PVP-nanogels. In this presentation, the origin of nanogel size control and functionalization are discussed in relation to dose, dose rate, polymer concentration and chemical conditions. The latter can be directly altered by purging the solutions with N2O or N2 or indirectly through the formation of H2O2 in systems with low polymer concentration. The discussion is based on recent experimental work and kinetics simulations. this understanding offers a new dimension for the design and production of radiation-sculptured multifunctional nanocarriers from aqueous solutions of polymers. In addition, the inherent boundaries of these systems in terms of processing parameters are explored.

(1) Background: A new family of nanosystems able to discern between normal and tumor cells and to release a therapeutic agent in controlled way were synthetized by e-beam irradiation. This technique permits to obtain biocompatible, sterile, carboxyl-functionalized polyvinylpyrrolidone (PVP-co-acrylic acid) nanogels (NGs); (2) Methods: Here, we performed a targeting strategy based on the recognition of over-expressed proteins on tumor cells, like the folate receptor. The selective targeting was demonstrated by co-culture studies and flow cytometry analysis, using folate conjugated NGs. Moreover, nanoparticles were conjugated to a chemotherapeutic drug or to a pro-apoptotic siRNA through a glutathione sensitive spacer, in order to obtain a controlled release mechanism, specific for cancer cells. The drug efficiency was tested on tumor and healthy cells by flow cytometric analysis, confocal and epifluorescence microscopy and cytotoxicity assay; the siRNA effect was investigated by RNAi experiment; (3) Results: The data obtained showed that the use of NGs permits a faster cargo release in cancer cells, in response to high cytosolic glutathione level, also improving their efficacy; (4) Conclusion: The possibility of releasing biological molecules in a controlled way and to recognize a specific tumor target allows overcoming the typical limits of the classic cancer therapy.

A growing body of evidence shows that Insulin, Insulin Receptor (IR) and IR signaling are involved in brain cognitive functions and their dysfunction is implicated in Alzheimer’s disease (AD) degeneration. Thus, administration of insulin could be a strategy for AD treatment. For this aim we have designed, synthesized and characterized a nanogel system (NG) to deliver insulin to the brain, as a tool for the development of a new therapy for AD. A carboxyl-functionalized poly(N-vinyl pyrrolidone) nanogel system produced by ionizing radiation was chosen as substrate for the covalent attachment of insulin or fluorescent molecules relevant for its characterization. Biocompatibility of the naked carrier was demonstrated by absence of cytotoxicity, oxidative stress and mitochondrial dysfunction. Hemocompatibility was demonstrated by hemolysis, coagulation time, leukocyte proliferation and inflammatory response tests. By immonufluorescence measurements we demonstrated that insulin conjugated to the NG (NG-In) is preotected by protease degradation and is able to bind and activate insulin receptor bringing to trigger the insulin signalling via AKT activation. Moreover, to provide consistent evidence on the functionality of the conjugated insulin on the glucose levels, the effect of NG-In was tested in mice demonstrating that plasma glucose levels was reduced. Neuroprotection of NG-In against dysfunction induced by amyloid β, a peptide mainly involved in AD, was verified. Finally, the potential of NG-In to be efficiently transported across the Blood Brain Barrier was demonstrated by using an in vitro system. All together these results indicated that the synthesized NG-In was a suitable vehicle system for insulin delivery in biomedicine and a very promising tool to develop new therapies for neurodegenerative diseases. The research eas supported by MIUR, FLAGSHIP PROJECT NanoMAX.

I nanogeli sono nanoparticelle polimeriche reticolate idrofile. La struttura polimerica del nanogelo permette la coniugazione di molecole che possano esplicare azioni terapeutiche, diagnostiche e di indirizzamento attivo su siti bersaglio. Le caratteristiche di flessibilità e conformabilità del nanogelo, e delle sue maglie, ne favoriscono l’attraversamento delle barriere biologiche, l’interazione di eventuali ligandi esposti sulla superfice con i recettori target, un’azione protettiva nei confronti del principio attivo incorporato. L’irraggiamento con radiazioni ionizzanti di soluzioni acquose di polimeri è una metodologia sintetica interamente “water-based”, che garantisce rese elevate e che può conferire sterilità al prodotto. [1] Lo studio presentato illustra la possibilità di produrre nanogeli a base di polivinilpirrolidone con le caratteristiche desiderate in termini di dimensioni e con gruppi funzionali disponibili per reazioni di coniugazione con l’insulina. L’obiettivo è quello di realizzare un nanovettore in grado di veicolare l’insulina al cervello attraverso la mucosa nasale. Studi recenti hanno dimostrato che l’insulina è in grado di ridurre la tossicità del peptide beta amiloide (A, coinvolto nella patogenesi della malattia di Alzheimer (MA), e di esplicare una funzione neuroprotettiva. [2, 3] Sono state studiate le caratteristiche dimensionali del nanosistema, la biocompatibilità e la funzione di protezione dalla tossicità indotta da Anei confronti di cellule di neuroblastoma.

Nanogels are nanoscalar polymeric networks, characterized by a dynamic internal structure and a flexible adaptive shape. When they are used as drug carriers, their flexibility and shape changing ability can facilitate the bypass of biological barriers, ensure protection of the payload and enable interaction of any attached ligand with its receptors. Poly(N-vinyl pyrrolidone)-co-acrylic acid nanogels (NGs) have been produced by ebeam irradiation of diluted aqueous solutions of a water-soluble polymer in the presence of a small amount of acrylic acid. In particular, industrial accelerators and the typical set-ups and doses applied for sterilization have been used. [1, 2] Particle size, molecular weight and functionalization can be controlled by a proper selection of polymer concentration and irradiation parameters, such as dose-rate and total dose imparted [3]. In recent years, a growing body of evidence has linked insulin resistance and insulin action to Alzheimer’s Disease (AD), a condition also referred to as Type 3 Diabetes (T3D) [4,5]. Recently, it has been demonstrated that insulin is capable of reducing toxicity induced by A oligomers, the protein mainly involved in AD onset, by inhibition of the intrinsic apoptotic pathway [6]. Moreover, activation of insulin signaling provides a neuroprotective mechanism to counteract oxidative stress, mitochondrial damage and neurodegeneration triggered by A oligomers in neuroblastoma cells [7]. In the present work NGs have been conjugated to insulin (NG-In) to defend the hormone from enzymatic degradation, facilitate its crossing through a blood brain barrier model and protect the LAN5 cells from the damages induced by A oligomers addiction.

PANI aqueous nanocolloids in their acid-doped, inherently conductive form were synthesised by means of suitable water soluble polymers used as stabilisers. In particular, poly(vinyl alcohol) (PVA) or chitosan (CT) was used to stabilise PANI nanoparticles, thus preventing PANI precipitation during synthesis and upon storage. Subsequently, e-beam irradiation of the PANI dispersions has been performed with a 12 MeV Linac accelerator. PVA-PANI nanocolloid has been transformed into a PVA-PANI hydrogel nanocomposite by radiation induced crosslinking of PVA. CT-PANI nanoparticles dispersion, in turn, was added to PVA to obtain wall-to-wall gels, as chitosan mainly undergoes chain scission under the chosen irradiation conditions. While the obtainment of uniform PANI particle size distribution was preliminarily ascertained with laser light scattering and TEM microscopy, the typical porous structure of PVA-based freeze dried hydrogels was observed with SEM microscopy for the hydrogel nanocomposites. UV−visible absorption spectroscopy demonstrates that the characteristic, pH-dependent and reversible optical absorption properties of PANI are conferred to the otherwise optically transparent PVA hydrogels. Selected formulations have been also subjected to MTT assays to prove the absence of cytotoxicity.

In this work the influence of poly(N-vinyl pyrrolidone) (PVP) concentration in water on the organization and dynamics of the corresponding macro-/nanogel networks has been systematically investigated. Irradiation has been performed at the same irradiation dose (within the sterilization dose range) and dose rate. In the selected irradiation conditions, the transition between macroscopic gelation and micro-/nanogels formation is observed just below the critical overlap concentration (∼1 wt%), whereas the net prevalence of intra-molecular over inter-molecular crosslinking occurs at a lower polymer concentration (below 0.25 wt%). Dynamic–mechanical spectroscopy has been applied as a classical methodology to estimate the network mesh size for macrogels in their swollen state, while 13C NMR spin–lattice relaxation spectroscopy has been applied on both the macrogel and nanogel freeze dried residues to withdraw interesting information of the network spatial organization in the passage of scale from macro to nano.

Surface modification of polymeric films is a way to obtain final products with high performance for many specific and ad hoc tailored applications, e.g. in functional packaging, tissue engineering or (bio)sensing. The present work reports, for the first time, on the design and development of surface modified ethylene–acrylic acid copolymer (EAA) films with polyaniline (PANI), with the aim of inducing electrical conductivity and potentially enable the electronic control of a range of physical and chemical properties of the film surface, via a new “grafting from” approach. In particular, we demonstrate that PANI was successfully polymerized and covalently grafted onto flexible EAA substrates, previously activated. The final hybrid materials and the corresponding intermediates were fully characterized via FTIR, XPS, SEM–EDAX, mechanical and electrical tests. The mechanical properties of the films are not detrimentally affected by each treatment step, while a significant increase in electrical conductivity was achieved for the new hybrid materials.

The feasibility of electrosynthesis of coenzyme Q10 (1) by electrooxidation of tetramethoxy precursor (2) has been investigated at carbon, Pt and BDD anodes in a divided cell. The process strongly depends on the applied potential, anode material and water content of the solvent. At carbon anodes in CH3CN/CH2Cl2 + 0.15 M Bu4NBF4 at proper operative conditions high faradic efficiency (>60%) and excellent selectivity (95–97%) of the target product were obtained. Keywords: Electrosynthesis, Coenzyme Q10, Anodic oxidation

Controlled synthesis of nanoscalar and nanostructured materials enables the development of novel functional materials with fine-tuned optical, mechanical, electronic, magnetic, conductive and catalytic properties that are of use in numerous applications. These materials have also found their potential use in medicine as vehicles for drug delivery, in diagnostics or in combinations thereof. In principle, nanoparticles can be divided into two broad categories, organic and inorganic nanoparticles. For both types of nanoparticles there are numerous possible synthetic routes. Considering the large difference in nature of these materials and the elementary reactions involved in the synthetic routes, most manufacturing techniques are complex and only suitable for one type of particle. Interestingly, radiation chemistry, i.e., the use of ionizing radiation from radioisotopes and accelerators to induce nanomaterials or chemical changes in materials, has proven to be a versatile tool for controlled manufacturing of both organic and inorganic nanoparticles. The advantages of using radiation chemistry for this purpose are many, such as low energy consumption, minimal use of potentially harmful chemicals and simple production schemes. For medical applications one more advantage is that the material can be sterile as manufactured. Radiation-induced synthesis can be carried out in aqueous systems, which minimizes the use of organic solvents and the need for separation and purification of the final product. The radiation chemistry of water is well known, as are the various ways of fine-tuning the reactivity of the system towards a desired target by adding different solutes. This, in combination with the controllable and adjustable irradiation process parameters, makes the technique superior to most other chemical methods. In this review, we discuss the fundamentals of radiation chemistry and radiation-induced synthesis of nanoparticles in aqueous solutions. The impact of dose and dose rate as well as of controlled addition of various solutes on the final particle composition, size and size distribution are described in detail and discussed in terms of reaction mechanism and kinetics.

Nanogels (NGs) are systems created by crosslinking of polymers taking nanosized dimensions and they have been proposed for biomedical and pharmaceutical applications due to their soft consistency, biocompatibility and good chemical properties that make them excellent drug delivery agents (1). Differently from typical hydrogels, nanogels are able to dissolve in solvents and to swell releasing the drug molecules loaded in the nano-vector. Furthermore, if properly functionalized with reactive groups, these materials can represent a very interestingly vector for different pharmacological treatments (2). Several methods have been investigated to prepare polymeric nanogels starting from preformed polymer chains, such those based on high energy ionizing radiations or accelerated electrons which induce generation of free radicals on the polymer backbone (3). These active centers can undergo inter and/or intramolecular combination thus leading to the generation of a 3D network. Other authors have studied more simple methods to generate hydroxyl radicals in aqueous environment such as those based on Fenton reactions. On the other hand, electro-oxidation processes are well known to allow the abatement of recalcitrant organic compounds by the action of electro generated hydroxyl radicals (4). In this contest, we have focused the attention on three different electrochemical processes, characterized by different nature and reactivity of electrogenerated hydroxyl radicals: - Electro-generation of phisisorbed hydroxyl radicals at Boron Doped Diamond (BDD) “non-active anodes”; - Electro-generation of chemisorbed hydroxyl radicals at DSA (Ti/IrO2-Ta2O5) “active anodes”; - Electro-generation of homogeneous hydroxyl radicals by electro-Fenton (EF) Clear evidences of intramolecular crosslinking of poly(vinylpyrrolidone) macromolecular chains were obtained when the electrogeneration of homogeneous hydroxyl radicals was carried out by an electro-Fenton process. This reaction was confirmed by a reduction of the average gyration diameter of the chains in solution detected by dynamic light scattering accompanied by narrowing of the molecular weight distribution of the polymer. This is the first indication that an electrochemical method can be used to generate hydroxyl radicals that can be used to modify the molecular architecture of preformed polymers. Work is in progress to evaluate the effect of many operating parameters, such as flow dynamic regime, current density, working potential and temperature.

Functionalized skin-like membranes are currently under investigation for the design of a new class of Epidermal Electronics devices for sensing and healing applications. The dynamic response of epidermal antennas in presence of absorption and release of fluids is a key-point to design RFID radio-sensors and actuators. This paper addresses the characterization of the dielectric property of PVA-based biocompatible hydrogel membranes in the UHF RFID band by means of a modified ring resonator. Samples having different compositions are measured in the dry state as well as when exposed to a progressive release of body fluids emulating perspirations or wound exudates. It was found that the permittivity increases up to 10 times demonstrating that such membranes may be also used as sensors.

In recent years, polymer nanocomposites have fascinated scientists, engineers and industrialists on the premise that the creation of new and more performing polymeric materials is possible by the combination of different building blocks with controlled dimensions at the nanoscale. Unfortunately, uniform dispersion of the hetero-phase domains within the plastic matrix or on its surface often fails due to the unfavorable thermodynamics, thus resulting in migration and irreversible aggregation phenomena. In-situ generation of a dispersed hetero-phase within the same polymer matrix or in its precursors increases the chances of achieving a better control of morphology by eliminating the often critical harvesting and re-dispersion steps in the manufacturing process. Strong interaction at the interface must be also provided to avoid aggregation and coarse phase-separation in usage. With this purpose, radiation grafting of a functional monomer onto polypropylene film has been applied to modify the molecular structure and properties of the otherwise chemically inert film. The radiation-grafted film has become permeable to the precursors of polymerization of a conducting polymer, namely polyaniline that can grow as a thin skin from its surface as well as an interpenetrated network into the film. Chemical attachment of the conducting polymer to the polyolefin has been demonstrated. The nanocomposite film shows an increase of electrical conductivity of several orders of magnitudes and amenability to be used as flexible electrode. In consideration of the well-known possibility of controlling the extent and depth of chemical modification of a substrate by radiation grafting, by tuning both system composition and irradiation conditions, this approach can enable a good degree of control of the morphology of the heterophase that forms on or within the substrate and thereby of the nanocomposite film. The recourse to suitable carriers, as chaperones of active molecules or nanoparticles into structurally different polymer matrices, is another possible strategy to obtain more uniform and stable dispersions. For this purpose, the possibility of obtaining colloidally stable micro-/nanoparticles from a partially degalactosylated xyloglucan (Deg-XG) has been investigated. 60Co γ-irradiation was applied to reduce the size of polymeric clusters in water. Irradiation was performed on the solid powder in air, up to a maximum dose of 60 kGy. FTIR and GPC analyses do not evidence any significant change of functional groups of the polymer and its average molecular weight, respectively. Deconvolution of GPC curves point to a change in the proportion between two main fractions of different molecular weight clusters, with a prevailing contribution of the lower over the higher MW clusters at the increase of the absorbed dose. Aqueous dispersions of the irradiated materials at low concentrations were characterized by dynamic light scattering measurements as function of the time and at different temperatures. For all systems an increase of scattered light intensity as function of the time at 37°C was observed. The fastest kinetics and the highest pseudo-plateau were shown by the 20 kGy irradiated system. Globular particles with 300-400 nm hydrodynamic diameters are formed. Their propensity to incorporate hydrophobic small guest molecules or high molecular weight biomolecules was assessed. The possibility of preparing optically transparent films from native xyloglucan incorporating these particles by solvent casting was demonstrated.

Nanogels (NGs), or small particles formed by physically or chemically crosslinked polymer networks, represent a niche in the development of “smart” nanoparticles for drug delivery and diagnostics. Yet, they offerunique advantages over other systems, including a large and flexible surface for multivalent bio-conjugation; an internal 3D aqueous environment for incorporation and protection of (bio)molecular drugs; the possibility to entrap light-activemolecules, metal or mineral nanoparticles for imaging or phototherapeutic purposes; stimuli-responsiveness to achieve temporal and/or site control of the release function and biocompatibility. The availability of inexpensive, robust and versatile synthetic methodologies is at the basis of the development of effective nanogel-based theragnostic devices. In particular, we have established that nanogels can be produced with high yields and through-puts by pulsede-beam irradiation of dilute aqueous solutions of water-soluble biocompatible polymers e.g. poly(N-vinyl pyrrolidone), and functional acrylic monomers, such as acrylic acid or (3-aminopropyl) methacrylamide hydrochloride, using industrial electron accelerators and set-ups (see Figure 1). [1-4] Nanogels are the result of chemical follow-up reactions initiated by a continuous series of electron pulse-generated hydroxyl radicals in de-aerated water. A number of radical sites are generated on the polymer chains,which may have a different fate depending onthe system composition and irradiation conditions.Intra-molecular and inter-molecular radical recombination as well as disproportionation, chain scission and monomer or short polymer segments grafting may occur up to different extent. As a result, crosslinked-core nanoparticles with multi-armed surfaces can be generated, with controlled size, crosslinking density, surface electric charge density, number and nature of functional groups.No recourse to organic solvents, toxic initiators or catalysts and surfactants is made, therefore expensive or time-consuming purification procedures are not required. Simultaneous sterilization can be achieved depending on the irradiation doses. Long-term colloidal stability in the formof aqueous dispersions and redispersability from the freeze-dried form are advantageous properties especially in the view of a pharmaceutical use. Nanogels have been decorated with fluorescent probes, peptides, antibodies or oligonucleotides and/or conjugated to both molecular and macromolecular model drugs to demonstrate their amenability to be transformed into bio-hybrid, smart drug nanocarriers. All the base nanogels have been proved to benot cytotoxic or genotoxic at the cellular level. Indeed, they showed a good affinity for cells, as they rapidly and quantitatively bypass the cellularcompartments, to accumulate in specific cell portions for the first hours, to bethen completely released from the cells after 24 h.[5] In particular, active targeting features toward specific cell types and smart delivery functions of model chemotherapeutics of purposely designed bio-hybrid nanogels will be presented.

Injectable polymer scaffolds are particularly attractive for guided tissue growth and drug/cell delivery with minimally invasive intervention. In the present work, "all-polymeric" gelling systems based on pectins and water-soluble maltose-conjugated chitosans (CM) have been developed. Maltose-conjugated chitosan has been synthesized at three different molar ratios, as evaluated by FITR analysis and fluorimetric titration. A thorough rheological characterization of the blends and their parent solutions has been performed. Macroscopic gelation has been achieved by mixing the high esterification degree pectins with CM at higher maltose grafted to chitosan contents. Gels form in a few minutes and reach their full strength in less than two hours. These features encourage their further development as scaffold for tissue engineering. (C) 2014 Elsevier Ltd. All rights reserved.

Aims and objectives Methods and materials Results Conclusion Personal information References, Aims and objectives: High dosages of (Gd3+)-based T1contrast agents (CAs) are required for MRI of tumors, in order to overcome the limitations due to their low sensitivity and inefficient accumulation at the target site, potentially causing sides effects or even sever...

Nanogels (NGs) synthesized by pulsed electron-beam irradiation of semi-dilute poly (N-vinyl pyrrolidone) (PVP) aqueous solutions, at relatively low energy per pulse and doses within the sterilization dose range, represent a very interesting family of polymeric nanocarriers. Ionizing irradiation-induced crosslinking of PVP allows to control particle size, and surface chemistry of the polymer nanoparticles without making use of catalysts, organic solvents or surfactants, and with beneficial effects onto the purity and hence biocompatibility of the final products obtained. Furthermore, the availability of reactive functional groups, either generated by the radiation or purposely grafted via copolymerisation with suitable functional monomers enables the conjugation of therapeutics drug, that make them suitable nanocarriers for biomedical applications. In particular, we have developed a carboxyl-functionalized nanogel variant for glutathione-mediated delivery of a chemotherapeutic agent, Doxorubicin. The drug is linked to the nanoparticles through a linker containing a cleavable disulphide bridge, aminoethyldithiopropionic acid (AEDP). In vitro drug release experiments have shown that glutathione can induce the release of Doxorubicin, through the reduction of the disulfide bridge. These results suggest that such redox-responsive nanoparticles can deliver doxorubicin into the nuclei of tumor cells, thus inducing inhibition of cell proliferation, and provide a favourable platform to construct nanoscalar drug delivery systems for cancer therapy.

Pulsed electron-beam irradiation of a semi-dilute poly(N-vinyl pyrrolidone) (PVP) aqueous solution in the presence of acrylic acid has led to a carboxyl functionalized nanogel system. Nanoparticles hydrodynamic size and surface charge density, in water and as a function of pH, were investigated by dynamic light scattering and laser doppler velocimetry, respectively. Nanogels (NGs) were proved not to be cytotoxic at the cellular level. Indeed, they rapidly bypass the cellular membrane to accumulate in specific cell portions of the cytoplasm, in the perinuclear area. The availability of pendant carboxyl groups on the crosslinked PVP NGs core prompted us to attempt their decoration with a single strand oligonucleotide, which holds a terminal amino group. The recognition ability of the attached single helix of its complementary strand was investigated. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39774.

Epoxy/carbon fibre reinforced composites were produced by means of e-beam irradiation through a pulsed 10 MeV electron beam accelerator. The matrix consisted of a difunctional epoxy monomer (DGEBA) and an initiator of cationic polymerisation, while the reinforcement was a unidirectional high modulus carbon fibre fabric. Dynamic mechanical thermal analysis was carried out in order to determine the cross-linking degree. The analysis pointed out a nonuniformity in the cross-linking degree of the e-beam cured panels, with the formation of clusters at low Tg (glass transition temperature) and clusters at high Tg. An out-of-mould post irradiation thermal treatment on e-beam cured samples provides a higher uniformity in the network although some slight degradation effects. Mode I delamination fracture toughness and Interlaminar Shear Strength (ISS) were also investigated by means of Double Cantilever Beam (DCB) and Short Beam Shear tests, respectively. Results from this mechanical characterisation allowed to correlate fracture toughness of the bulk matrix resin, cross-linking density and fibre/matrix interaction to the delamination fracture behaviour of the fibre reinforced material.

This paper deals with a novel class of optical sensors for ethanol vapor, based on polystyrene opals infiltrated with a hydrogel sensitive to ethanol. Optical characterization of such opals has been performed, proving their effectiveness as sensors

Chemical sensing using optics has been under extensive research all over the world during last decades and many optical chemical sensors are nowadays finding increasing applications in industry, environmental monitoring, medicine, biomedicine and chemical analysis. These optical sensors can be based on various optical principles, such as absorbance, reflectance or transmittance, luminescence and fluorescence, covering different regions of the spectrum (UV, visible, IR, NIR). Optical chemical sensors have several advantages over conventional electricity-based sensors, in terms of selectivity, immunity to electromagnetic interference, higher sensitivity, and they are also relatively inexpensive and minimally invasive. A wide class of optical chemical sensors is based on Photonic Crystals (PCs), i.e. regular arrays of materials with different refractive indices. In particular, they are artificial structures with a periodic dielectric function. In this paper, we present the optical characterization of a polystyrene opal, infiltrated with a stimuli responsive hydrogel specifically formulated to be sensitive to ethanol (EtOH), also in the presence of water. Stimuli-responsive hydrogels are interesting materials for sensing applications due to thefact that they can change their volume significantly in response to small alterations of certain environmental parameters. In fact, hydrogels are increasingly considered as responsive materials to generate active inverse opals fortheir ability to exhibit significant reversible diffraction shifts as a response of a variety of stimuli, such astemperature, pH and ionic strength, single molecules binding and mechanical forces.The stimuliresponsiveness must be accompanied by adequate elasticity and chemical stability forthe inverse opal to be able to survive, without collapsing, to the template removal process byorganic solvents (for polymer colloids) during preparation and to withstand repeated swelling/deswelling cycles when in use, as well as erosion due to prolonged exposure to the swelling medium. While there are interesting studies which report diffraction shifts in a wide region of the visible spectral region when e.g. a crosslinked 2-hydroxyethyl methacrylate (HEMA) hydrogel is exposed either to pure liquid water or to concentrated ethanol/water liquid solutions, at the best of our knowledge there are no equivalent studies which report on the ability of hydrogel inverse opals tospecifically respond to ethanol vapors when already swollen by water.The hydrogel network should be designed so that it can uptake and retain water, when exposed towater vapor-rich atmospheres, and further swell when the atmosphere which is exposed to isprogressively concentrated of ethanol vapors. For this purpose, 2-hydroxyethyl methacrylate (HEMA) was used as main building block for the network, for its known favorable Flory-Hugginsmixing parameter with ethanol; acrylic acid (AA) at two different ratios was also considered as co-monomerfor its affinity toward water and its contribution to hydrogel network mechanicalproperties, due to establishment of further crosslinking through strong secondary interactions;finally poly-ethylene glycol-200dimethacrylate (PEG200DMA) was used as crosslinking agent. The polymerization process combined a “cold” UV-photocrosslinking step and a thermal post-cure.Preliminary swelling studies in the presence of both liquid ethanol and ethanol vapors were carried out on the macrogel analogue as well as a dynamic mechanical thermal analysis to withdraw usefulinformation on the hydrogels mechanical spectra and validate both the formulation and curingprocess. The most promising of the two formulations was selected to infiltrate a polystyrene (PS)opal structure, which was generated onto pre-etched silica through self-assembly of PS nanoparticles. The periodically nanostructured hydrogel film (Fig.1) was then evaluated as active component of an ethanol vapor optical sensor by means of UV-Vis transmission measurements atthe variance of ethanol vapor concentration (Fig.2).

Aminopropyl methacrylamide chloride-graft-poly(N-vinyl pyrrolidone) nanogels (NGs) were designed to exploit the favorable properties of poly(N-vinyl pyrrolidone) (PVP), such as its high affinity to water and complexation ability of ions, molecules and macromolecules, with the availability of primary amino groups for bioconjugation reactions. A thorough structural characterization of the nanoscalar networks was performed via 1 H NMR and solid state 13 C NMR spectroscopies, while solid state NMR relaxation time measurements completed the NGs description in terms of polymer network density. Information on the hydrodynamic size and surface charge densities were sought via dynamic light scattering (DLS) and ζ-potential measurements. These measurements, carried out both in water and in buffer and at the variance of pH, temperature and time, support the excellent colloidal stability of the amino-graft PVP nanogels and their redispersability from the dry physical form. The total absence of in vitro toxicity and immunogenicity was ascertained first, and then cell localization studies in cell cultures of fluorescent variants were performed. Furthermore, the possibility of decorating the nanogels with bovine serum albumin (BSA) to obtain a stable bio-hybrid colloidal nanoconstruct was established. All the gathered evidences qualify these materials as potential candidates to be used as nanocarriers for intra-cellular delivery of protein and other biomolecular drugs.

A scalable, single-step, synthetic approach for the manufacture of biocompatible, functionalized micro- and nanogels is presented. In particular, poly(N-vinyl pyrrolidone)-grafted-(aminopropyl)methacrylamide microgels and nanogels were generated through e-beam irradiation of PVP aqueous solutions in the presence of a primary amino-group-carrying monomer. Particles with different hydrodynamic diameters and surface charge densities were obtained at the variance of the irradiation conditions. Chemical structure was investigated by different spectroscopic techniques. Fluorescent variants were generated through fluorescein isothiocyanate attachment to the primary amino groups grafted to PVP, to both quantify the available functional groups for bioconjugation and follow nanogels localization in cell cultures. Finally, a model protein, bovine serum albumin, was conjugated to the nanogels to demonstrate the attachment of biologically relevant molecules for targeting purposes in drug delivery. The described approach provides a novel strategy to fabricate biohybrid nanogels with a very promising potential in nanomedicine.

In this paper we report for the first time on the emissive behavior of two polyaniline (PANI) nanoparticle systems produced via oxidative chemical polymerization in the presence of either poly(vinyl alcohol) (PVA) or chitosan as polymeric stabilizers in water. The emission from PANI nanoparticles is irreversibly quenched by an increase of pH of the suspending medium from acid to neutral (chitosan–PANI) or alkaline (PVA–PANI). Conversely, PANI nanorods synthesized in the same conditions of the above, but in presence of poly(N-vinyl pyrrolidone), is not emissive at any pH. The role of the polymeric surfactant as a soft template is key in controlling the morphology and the properties of the obtained PANI dispersions. FTIR, UV–Vis absorption and photoluminescence excitation (PLE) spectra studies suggest that the emissive properties are related to the establishment of strong, non-covalent interactions between nanoscalar PANI particles and the polymeric surfactant at the pH of synthesis. Morphology examination of the three systems, by both dynamic light scattering (DLS) and Transmission Electron Microscopy (TEM), reveal that photoluminescence is associated to the presence of a genuinely 3D nanoscalar morphology, together with an ordered disposition of PANI chains into aligned crystal planes. Concomitant to the irreversible quenching of the emission signal with increasing pH, there is an evolution of the morphology leading to particle coalescence, coarsening and ultimately phase-separation, with consequent modification of PANI–polymeric surfactant interactions, PANI chains supra-molecular organization and optical properties of the PANI nanoparticles dispersion.