Inherently fluorescent polyaniline nanoparticles in a dynamic landscape

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

Glutathione-sensitive nanogels for drug release

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

RADIATION CROSSLINKED ADVANCED WOUND DRESSING CONTAINING EGG WHITE PROTEINS

During the past decades, the use of antibiotics has grown worldwide in different fields, from medicine to agriculture, leading to antibiotic resistance of microbes, which is the cause of thousands of deaths every year worldwide. [1, 2] Finding new antibiotics is becoming more and more difficult because their development is no longer convenient in term of the cost–benefit ratio for the pharmaceutical industry. The interest in egg white proteins, such as ovoalbumin, ovotransferrin and lysozyme, has risen especially because of their demonstrated antimicrobial activities. [3] These antimicrobial proteins can then be used to enrich wound dressing films that requires a high level of control of microbial colonization. Wound dressing films can be easily produced crosslinking polymers, such as polyvinyl alcohol (PVA) or polyvinyl pyrrolidone, by high-energy radiation. [4] This technique does not require expensive initiators and catalysts and, depending on the irradiation doses, it can guarantee simultaneous product sterilization. PVA hydrogels obtained by irradiation are also transparent, a desirable property for wound dressings. When PVA is mixed with selected polysaccharides, the dressings have shown faster healing rates and scarless healing, probably due to antioxidant properties of polysaccharide fragments produced upon irradiation. [4] Therefore, the aim of this work is to develop hydrogel would dressings based on the irradiation of PVA and xyloglucan (XG) blends and to investigate the antibacterial properties of the films due to the incorporation of egg white proteins

Facile crosslinking of poly(vinylpyrrolidone) by electro-oxidation with IrO2-based anode under potentiostatic conditions

The modification of polymer architectures by reaction with chemically adsorbed hydroxyl radicals has been thoroughly investigated by electrolyzing dilute aqueous solutions of the biocompatible polymer poly(vinylpyrrolidone) (PVP), using an undivided electrolytic cell with a Ti/IrO2-Ta2O5 (DSA®) anode. Several electrolyses were performed to assess the influence of the applied potential, the circulated charge and the PVP concentration, which was always kept low to avoid chain overlapping. From the results obtained, it can be concluded that the electro-oxidation of PVP solutions using a cheap anode is an effective method to crosslink initially isolated polymer chains, eventually increasing the size of their random coils. Furthermore, the average size of the modified macromolecules can be controlled by tuning the electrode potential and/or the current density and the circulated charge. At high anodic potential values, the hydroxyl radicals formed at DSA® were also effective to generate reactive functional groups on the PVP backbone, which is a very interesting feature for future biomedical applications

Synthesis of polymer nanogels by electro-Fenton process: investigation of the effect of main operation parameters

Recently, electro-Fenton (EF) process has been shown as a promising, facile, effective, low cost and environmentally-friendly alternative for synthesizing polymer nanogels suitable as biocompatible nanocarriers for emerging biomedical applications. Here, the electrochemically-assisted modification of poly(vinylpyrrolidone) (PVP) by EF process was studied to assess the role of key operation parameters for a precise modulation of polymer crosslinking and its functionalization with -COOH and succinimide groups. The dimensions of the nanogels, in terms of hydrodynamic radius (Rh) and weight-average molecular weight (Mw), can be tuned up by controlling the electrolysis time, current density (j) and PVP and Fe2+ concentrations, as demonstrated via dynamic and static light scattering and gel permeation chromatography analysis. Using PVP at 0.25 wt.%, Fe2+ at 0.5-1.0 mmol dm-3 and low j, short treatment times induced intramolecular crosslinking with chain scission, allowing size reduction of PVP particles from 24 to 9-10 nm. Longer reaction times and higher PVP and Fe2+ contents favored intermolecular crosslinking ending in Mw values higher than the initial 3.95×105 g mol-1. An excessive ¿OH dose from a too high circulated charge (Q), i.e., too prolonged electrolysis time even at low j or too high j even for short time, promoted intramolecular crosslinking (Rh ~ 10-12 nm) along with a very significant chain scission probably owing to the loss of mobility of the three-dimensional nanogel network. In conclusion, EF allowed transforming the architecture of linear, inert PVP chains into a functionalized nanogel with -COOH and succinimide groups that have great potential for further conjugation

Water-borne Polymeric Nanoparticles for Glutathione-Mediated Intracellular Delivery of Anticancer Drugs.

A new family of water-borne, biocompatible and carboxyl- functionalized nanogels was developed for glutathione- mediated delivery of anticancer drugs. Poly(N-vinyl- pyrrolidone)-co-acrylic acid nanogels were generated by e- beam irradiation of aqueous solutions of a crosslinkable polymer, using industrial-type linear accelerators and set- ups. Nanogels physico-chemical properties and colloidal stability, in a wide pH range, were investigated. In vitro cell studies proved that the nanogels are fully biocompatible and able to quantitatively bypass cellular membrane. An anticancer drug, doxorubicin (DOX), was linked to the carboxyl groups of NGs through a spacer containing a disulphide cleavable linkage. In vitro release studies showed that glutathione is able to trigger the release of DOX through the reduction of the S-S linkage at a concentration comparable to its levels in the cytosol

Gadolinium-chelating nanogels as MR contrast agesnts specifically targeting tumor cells

Development of multifunctional nanogels coordinating paramagnetic ions and displacing targeting ligands for preferential accumulation into tumors. Low molecular-weight Gd-chelates are widely used in clinical MRI for various purposes. However, these contrast agents (CAs) have several shortcomings: they rapidly extravasate from blood vessels to the interstitial space, have a short circulation times and show poor contrast at high magnetic fields. Incorporating gadolinium into flexible nanogels has the potential of increasing intravascular half-life, accumulation and retention in specific body compartments of the CA as well as increasing the MR signal, since many metal ions can be coordinated to the same nanoparticl

Neurological Consequences, Mental Health, Physical Care, and Appropriate Nutrition in Long-COVID-19

SARS-CoV-2 pandemic has caused a collapse of the world health systems. Now, vaccines and more effective therapies have reversed this crisis but the scenario is further aggravated by the appearance of a new pathology, occurring as SARS-CoV-2 infection consequence: the long-COVID-19. This term is commonly used to describe signs and symptoms that continue or develop after acute infection of COVID-19 up to several months. In this review, the consequences of the disease on mental health and the neurological implications due to the long-COVID are described. Furthermore, the appropriate nutritional approach and some recommendations to relieve the symptoms of the pathology are presented. Data collected indicated that in the next future the disease will affect an increasing number of individuals and that interdisciplinary action is needed to counteract it