Development of Biocomposite Polymeric Systems Loaded with Antibacterial Nanoparticles for the Coating of Polypropylene Biomaterials.

The development of a biocomposite polymeric system for the antibacterial coating of polypropylene mesh materials for hernia repair is reported. Coatings were constituted by a film of chitosan containing randomly dispersed poly(d,l-lactide--glycolide) (PLGA) nanoparticles loaded with chlorhexidine or rifampicin. The chlorhexidine-loaded system exhibited a burst release during the first day reaching the release of the loaded drug in three or four days, whereas rifampicin was gradually released for at least 11 days.

A novel strategy to polyurethanes with improved mechanical properties by photoactivation of amidocoumarin moieties.

An attractive strategy involving photodimerization of a novel amidocoumarin moiety is presented to prepare polyurethane coatings with excellent mechanical properties. Two families of polyurethanes containing these chromophore units into soft or hard segments were easily synthesized by inserting a small fraction of amidocoumarin-diol (5 wt% or 10 wt%). A systematic study has been carried out comparing hard segment, chromophore content and the influence of this amidocoumarin unit within the hard or soft segment.

Anti-staphylococcal hydrogels based on bacterial cellulose and the antimicrobial biopolyester poly(3-hydroxy-acetylthioalkanoate-co-3-hydroxyalkanoate).

Polymeric hydrogels from bacterial cellulose (BC) have been widely used for the development of wound dressings due to its water holding capacity, its high tensile strength and flexibility, its permeability to gases and liquids, but lacks antibacterial activity. In this work, we have developed novel antimicrobial hydrogels composed of BC and the antimicrobial poly(3-hydroxy-acetylthioalkanoate-co-3-hydroxyalkanoate) (PHACOS). Hydrogels based on different PHACOS contents (20 and 50 wt%) were generated and analysed through different techniques (IR, DSC, TGA, rheology, SEM and EDX) and their bactericidal activity was studied against Staphylococcus aureus.

Chitosan hydrogels functionalized with either unfractionated heparin or bemiparin improve diabetic wound healing.

Diabetes mellitus causes severe impairment in the cutaneous wound healing process, which has led to extensive research striving to establish new treatments. In this work, we describe the effects of chitosan hydrogels functionalized with either unfractionated heparin or bemiparin (a low molecular weight heparin, LMWH) as topical treatments in an experimental diabetic wound healing model. Although wound morphometry showed similar values at the end of the study, microscopic analyses revealed impaired healing in diabetic animals in terms of inflammation and tissue formation.

On-Surface Driven Formal Michael Addition Produces m-Polyaniline Oligomers on Pt(111).

On-surface synthesis is emerging as a highly rational bottom-up methodology for the synthesis of molecular structures that are unattainable or complex to obtain by wet chemistry. Here, oligomers of meta-polyaniline, a known ferromagnetic polymer, were synthesized from para-aminophenol building-blocks via an unexpected and highly specific on-surface formal 1,4 Michael-type addition at the meta position, driven by the reduction of the aminophenol molecule. We rationalize this dehydrogenation and coupling reaction mechanism with a combination of in situ scanning tunneling and non-contact atomic force microscopies, high-resolution synchrotron-based X-ray photoemission spectroscopy and first-principles calculations.

Molecular α-relaxation process of exopolysaccharides extracted from Nostoc commune cyanobacteria.

Broadband dielectric spectroscopy was used to investigate the molecular α-relaxation of the exopolysaccharides (EPS) extracted from Nostoc commune cyanobacteria. The EPS were modified in different ways. EPS were carboxymethylated to obtain carboxymethyl-exopolysaccharides (CEPS).

Anti-Inflammatory Polymeric Nanoparticles Based on Ketoprofen and Dexamethasone.

Polymeric nanoparticles that combine dexamethasone and naproxen reduce inflammation and synergistically inhibit Interleukin-12b () transcription in macrophages. This effect can be the result of a cyclooxygenase-dependent or a cyclooxygenase-independent mechanism. The aim of this work is to obtain potent anti-inflammatory polymeric nanoparticles by the combination of dexamethasone and ketoprofen, one of the most efficient cyclooxygenase-inhibitors among non-steroidal anti-inflammatory drugs, with appropriate hydrodynamic properties to facilitate accumulation and co-release of drugs in inflamed tissue.

Glycerylphytate crosslinker as a potential osteoinductor of chitosan-based systems for guided bone regeneration.

Chitosan-based membranes are promising systems for guided bone regeneration. In this work, we used glycerylphytate as ionic crosslinker and osteinductor compound for the fabrication of chitosan membranes as supports for human mesenchymal stem cells. Three different glycerylphytate-crosslinked membranes were developed by changing the crosslinker concentration, from 2.

Polymeric Nanoparticles that Combine Dexamethasone and Naproxen for the Synergistic Inhibition of Il12b Transcription in Macrophages.

Recent studies have demonstrated in vivo synergistic immunosuppressive and anti-inflammatory capacity of dexamethasone (Dx) and naproxen (NAP) in collagen-induced arthritis (CIA) rats. However, the molecular basis of this synergistic effect is barely understood. The low solubility of these drugs and their adverse effects hamper their efficacy on the treatment of inflammatory processes making nanoparticulated systems promising candidates to overcome these drawbacks.

Highly Deformable Porous Electromagnetic Wave Absorber Based on Ethylene-Propylene-Diene Monomer/Multiwall Carbon Nanotube Nanocomposites.

The need for electromagnetic interference (EMI) shields has risen over the years as the result of our digitally and highly connected lifestyle. This work reports on the development of one such shield based on vulcanized rubber foams. Nanocomposites of ethylene-propylene-diene monomer (EPDM) rubber and multiwall carbon nanotubes (MWCNTs) were prepared via hot compression molding using a chemical blowing agent as foaming agent.

In situ NMR metrology reveals reaction mechanisms in redox flow batteries.

Large-scale energy storage is becoming increasingly critical to balancing renewable energy production and consumption. Organic redox flow batteries, made from inexpensive and sustainable redox-active materials, are promising storage technologies that are cheaper and less environmentally hazardous than vanadium-based batteries, but they have shorter lifetimes and lower energy density. Thus, fundamental insight at the molecular level is required to improve performance.

Design of Rubber Composites with Autonomous Self-Healing Capability.

The development of self-healing rubbers is currently under investigation as a strategy to promote their reuse and, hence, reduce their waste. However, autonomous, multicycle self-healing rubbers with good mechanical properties have so far proven difficult to achieve. Here, mechanically robust composites based on epoxidized natural rubber (ENR) and thermally reduced graphene oxide (TRGO) were successfully designed and prepared with a high healing efficiency of up to 85% at room temperature without applying external stimuli.

A Methodology Towards Mechanical Properties Optimization of Three-Component Polymers by the Gradual Variation of Feed Composition in Semi-Continuous Emulsion-Free Radical Polymerization.

In this work, a new methodology for the synthesis of three-component polymers (TCPs) was developed using a seeded, semi-continuous free-radical emulsion polymerization towards the optimization of the moduli-ultimate deformation performance and energy dissipation capacity for a styrene (S), n-butyl acrylate (BA), and 4-vinylbenzyl chloride (VBC) system. The three components were sequentially fed in pairs, varying feed composition along the conversion using S as the common monomer. To prepare a reference material, an industrial method was utilized with those monomers, using an equivalent global composition in a two-stage batch process (TS).

Giving a Second Opportunity to Tire Waste: An Alternative Path for the Development of Sustainable Self-Healing Styrene-Butadiene Rubber Compounds Overcoming the Magic Triangle of Tires.

Current regulations demand tires with long lifetime and reduced fuel consumption without sacrificing car safety. However, tire technology still needs to reach a suitable balance between these three indicators. Here, we address them by developing a self-healing tire compound using styrene-butadiene rubber (SBR) as the matrix and reclaimed tire waste as the sustainable filler.

Glycerylphytate as an ionic crosslinker for 3D printing of multi-layered scaffolds with improved shape fidelity and biological features.

The fabrication of intricate and long-term stable 3D polymeric scaffolds by a 3D printing technique is still a challenge. In the biomedical field, hydrogel materials are very frequently used because of their excellent biocompatibility and biodegradability, however the improvement of their processability and mechanical properties is still required. This paper reports the fabrication of dual crosslinked 3D scaffolds using a low concentrated (<10 wt%) ink of gelatin methacryloyl (GelMA)/chitosan and a novel crosslinking agent, glycerylphytate (G1Phy) to overcome the current limitations in the 3D printing field using hydrogels.

Biocompatible Polymer Materials with Antimicrobial Properties for Preparation of Stents.

Biodegradable polymers are promising materials for use in medical applications such as stents. Their properties are comparable to commercially available resistant metal and polymeric stents, which have several major problems, such as stent migration and stent clogging due to microbial biofilm. Consequently, conventional stents have to be removed operatively from the patient's body, which presents a number of complications and can also endanger the patient's life.

A Way to Predict Gold Nanoparticles/Polymer Hybrid Microgel Agglomeration Based on Rheological Studies.

In this work, a detailed rheological study of hybrid poly(acrylamide--acrylic acid) P(AAmAAc) aqueous microgel dispersions is performed. Our intention is to understand how the presence of gold nanoparticles, AuNP, embedded within the microgel matrix, affects the viscoelastic properties, the colloidal gel structure formation, and the structure recovery after cessation of the deformation of the aqueous microgel dispersions. Frequency sweep experiments confirmed that hybrid microgel dispersions present a gel-like behavior and that the presence of AuNP content within microgel matrix contributes to the elasticity of the microgel dispersions.

How Confinement Affects the Nucleation, Crystallization, and Dielectric Relaxation of Poly(butylene succinate) and Poly(butylene adipate) Infiltrated within Nanoporous Alumina Templates.

This work describes the successful melt infiltration of poly(butylene succinate) (PBS) and poly(butylene adipate) (PBA) within 70 nm diameter anodic aluminum oxide (AAO) templates. The infiltrated samples were characterized by SEM, Raman, and FTIR spectroscopy. The crystallization behaviors and crystalline structures of both polymers, bulk and confined, were analyzed by differential scanning calorimetry (DSC) and grazing incidence wide angle X-ray scattering (GIWAXS).

HDPE/Chitosan Composites Modified with PE-g-MA. Thermal, Morphological and Antibacterial Analysis.

In this work, composites of high density polyethylene (HDPE) with chitosan were prepared by melt compounding in a laboratory internal mixer. Maleic anhydride grafted HDPE (PE-g-MA) in a concentration up to 25 phr was used as a compatibilizer to enhance the dispersing effect of chitosan in the HDPE matrix. The degree of crystallinity was investigated by X-ray diffraction (XRD) and the thermal properties were analyzed by differential scanning calorimetry (DSC) and thermogravimetry (TG).

Bioadhesive functional hydrogels: Controlled release of catechol species with antioxidant and antiinflammatory behavior.

Chronic wounds are particularly difficult to heal and constitute an important global health care problem. Some key factors that make chronic wounds challenging to heal are attributed to the incessant release of free radicals, which activate the inflammatory system and impair the repair of the wound. Intrinsic characteristics of hydrogels are beneficial for wound healing, but the effective control of free radical levels in the wound and subsequent inflammation is still a challenge.

New Poly(Propylene Imine) Dendrimer Modified with Acridine and Its Cu(II) Complex: Synthesis, Characterization and Antimicrobial Activity.

A second-generation poly(propylene imine) dendrimer modified with acridine and its Cu(II) complex have been synthesized for the first time. It has been found that two copper ions form complexes with the nitrogen atoms of the dendrimeric core by coordinate bonds. The new compounds have been characterized by nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), fourier-transform infrared spectroscopy (FTIR) and fluorescence spectroscopy.

Anti-inflammatory Surface Coatings Based on Polyelectrolyte Multilayers of Heparin and Polycationic Nanoparticles of Naproxen-Bearing Polymeric Drugs.

Immune response to biomaterials can produce chronic inflammation and fibrosis leading to implant failure, which is related to the surface properties of the biomaterials. This work describes the preparation and characterization of polyelectrolyte multilayer (PEM) coatings that combine the anti-inflammatory activity of heparin as polyanion with the potential release of Naproxen, a nonsteroidal anti-inflammatory drug from polymeric nanoparticles (NP) with cationic surface charge. The polyelectrolyte multilayers were characterized by physical methods to estimate multilayer growth, thickness, zeta potential, and topography.

Glycerylphytate compounds with tunable ion affinity and osteogenic properties.

Phytic acid (PA) is a natural-occurring antioxidant, which plays an important role in many biological processes. PA is recognized as a potent inhibitor of lipid peroxidation because of its high affinity to multivalent cations, and it can play a role in osteogenic processes. However, its powerful chelating capacity is controversial because it can lead to a severe reduction of mineral availability in the organism.