A Method for the Immobilization of Chitosan onto Urinary Catheters.

A method for the immobilization of an antibacterial chitosan coating to polymeric urinary medical catheters is presented. The method comprises a two-step plasma-treatment procedure, followed by the deposition of chitosan from the water solution. In the first plasma step, the urinary catheter is treated with vacuum-ultraviolet radiation to break bonds in the polymer surface film and create dangling bonds, which are occupied by hydrogen atoms.

Characterization of chitosan-lysine surfactant bioactive coating on silicone substrate.

Chitosan (Chi) and anionic surfactant derived from lysine (77KS) were used to prepare a novel bioactive coating and as a drug delivery system for amoxicillin (AMOX) on a model polydimethylsiloxane (PDMS) surface. The bioactive coating was formulated as polyelectrolyte-surfactant complex (PESC). Aggregation behaviour between the cationic Chi and oppositely charged 77KS in bulk was analysed using turbidity and ζ-potential measurement.

Rapid Water Softening with TEMPO-Oxidized/Phosphorylated Nanopapers.

Water hardness not only constitutes a significant hazard for the functionality of water infrastructure but is also associated with health concerns. Commonly, water hardness is tackled with synthetic ion-exchange resins or membranes that have the drawbacks of requiring the awkward disposal of saturated materials and being based on fossil resources. In this work, we present a renewable nanopaper for the purpose of water softening prepared from phosphorylated TEMPO-oxidized cellulose nanofibrils (PT-CNF).

Native cellulose nanofibrills induce immune tolerance in vitro by acting on dendritic cells.

Cellulose nanofibrills (CNFs) are attractive biocompatible, natural nanomaterials for wide biomedical applications. However, the immunological mechanisms of CNFs have been poorly investigated. Considering that dendritic cells (DCs) are the key immune regulatory cells in response to nanomaterials, our aim was to investigate the immunological mechanisms of CNFs in a model of DC-mediated immune response.

Enhanced catalytic activity of the surface modified TiO2-MWCNT nanocomposites under visible light.

Fusing multiwall carbon nanotubes (MWCNTs) with TiO2 at the nano-scale level promotes the separation of those electron-hole charges generated upon UV and daylight irradiation. In this study, we investigated facile sonochemical synthesis, combined with the calcination process for the preparations of TiO2-MWCNT composites with different mole ratios of titanium and carbon. In order to produce stable nano dispersions we exploited an innovative biotechnology-based approach for the covalent functionalizations of TiO2-MWCNTs with in-situ synthesized soluble phenoxazine dye molecules.

Surface-Sensitive Approach to Interpreting Supramolecular Rearrangements in Cellulose by Synchrotron Grazing Incidence Small-Angle X-ray Scattering.

The supramolecular rearrangements of biopolymers have remained difficult to discern. Here, we present a versatile approach that allows for an investigation of two major types of rearrangements typically observed with cellulose, the most abundant biopolymer on earth. Model thin films were employed to study time-resolved pore size changes using grazing incidence small-angle X-ray scattering (GISAXS) during regeneration and drying.

Effect of Low-Density Static Magnetic Field on the Oxidation of Ammonium by and by Activated Sludge in Municipal Wastewater.

Ammonium removal is a key step in biological wastewater treatment and novel approaches that improve this process are in great demand. The aim of this study is to test the hypothesis that ammonium removal from wastewater can be stimulated by static magnetic fields. This was achieved by analysis of the effects of static magnetic field (SMF) on the growth and activity of , a key ammonia-oxidising bacterium, where increased growth and increased ammonia oxidation rate were detected when bacteria were exposed to SMF at 17 mT.

Nanocelluloses and their phosphorylated derivatives for selective adsorption of Ag(+), Cu(2+) and Fe(3+) from industrial effluents.

The potential of nanoscaled cellulose and enzymatically phosphorylated derivatives as bio-adsorbents to remove metal ions (Ag(+), Cu(2+) and Fe(3+)) from model water and industrial effluents is demonstrated. Introduction of phosphate groups onto nanocelluloses significantly improved the metal sorption velocity and sorption capacity. The removal efficiency was considered to be driven by the high surface area of these nanomaterials as well as the nature and density of functional groups on the nanocellulose surface.

New findings about the lipase acetylation of nanofibrillated cellulose using acetic anhydride as acyl donor.

The acetylation efficiency of nanofibrillated cellulose (NFC) with acetic anhydride as acetyl donor was studied using lipase from Aspergillus niger in a mixture of dimethyl sulphoxide (DMSO) and phosphate buffer solution at ambient conditions and in supercritical carbon dioxide (scCO2). The chemical acetylation of NFC with comparable ester content was carried out for comparison. The ATR-FTIR, solid-state CP/MAS (13)C NMR and DSC analyses revealed that, besides the enzyme-catalysed acetylation, predominantly appearing at the C-6 position of cellulose hydroxyls, a strong and stable acyl-enzyme intermediate attachment also occurred on the NFC via Maillard reaction.

Characterisation and properties of homo- and heterogenously phosphorylated nanocellulose.

Nano-sized cellulose ester derivatives having phosphoryl side groups were synthesised by phosphorylation of nanofibrilated cellulose (NFC) and nanocrystaline cellulose (NCC), using different heterogeneous (in water) and homogeneous (in molten urea) processes with phosphoric acid as phosphoryl donor. The phosphorylation mechanism, efficacy, stability, as well as its influence on the NC crystallinity and thermal properties, were evaluated using ATR-FTIR and (13)C NMR spectroscopies, potentiometric titration, capillary electrophoresis, X-ray diffraction, colorimetry, thermogravimmetry and SEM. Phosphorylation under both processes created dibasic phosphate and monobasic tautomeric phosphite groups at C6 and C3 positioned hydroxyls of cellulose, yielded 60-fold (∼1,173 mmol/kg) and 2-fold (∼1.

Introduction of aldehyde vs. carboxylic groups to cellulose nanofibers using laccase/TEMPO mediated oxidation.

The chemo-enzymatic modification of cellulose nanofibers (CNFs) using laccase as biocatalysts and TEMPO or 4-Amino-TEMPO as mediators under mild aqueous conditions (pH 5, 30 °C) has been investigated to introduce surface active aldehyde groups. 4-Amino TEMPO turned out to be kinetically 0.5-times (50%) more active mediator, resulting to oxoammonium cation intermediacy generated and its in situ regeneration during the modification of CNFs.

Synergies of phenolic-acids' surface-modified titanate nanotubes (TiNT) for enhanced photo-catalytic activities.

The adsorption of chemically similar but differently oxygen reactive phenolic-acid derivatives on the Ti-nanotubes (TiNTs) surfaces to increase and/or broaden their photo-induced activity was studied using Raman and X-ray photoelectron spectroscopies combined with zeta-potential analyses. Photo-catalytic activities and stabilities of newly synthesized particles were evaluated by using high-resolution capillary electrophoresis in combination with cyclic voltammetry and spin-trapping EPR spectroscopy. The modification with caffeic acid (CA) resulted in well-oriented and dense but oxygen semi-stable thin layer (1-3 nm) of self-assembled mono-molecular and/or bi-dentate coordinated molecules on the TiNTs' surfaces, which narrowed the band gap from 2.

Processing of gelatin-based cryogels with improved thermomechanical resistance, pore size gradient, and high potential for sustainable protein drug release.

Porous gelatin (GEL) cryogels were processed by spatiotemporal and temperature-controlled gelation and freezing-lyophilizaton process, followed by zero-length crosslinking, using different molarities of reagents (EDC and NHS) and reaction media (100% PBS or 20/80% PBS/EtOH mixture) for variable time extensions (1-24 h). In this way, tuneable cryogels with gradient microporosity (from 100 µm to 1000 µm) were formed, being mainly influenced by crosslinkers' concentration and EtOH addition. Later affect the pore morphology (from round to ellipsoid), consequently modulating the steady-state physiological swelling profile toward twice lower values (∼ 600%) comparing to stepwise swelling of in 100% PBS media crosslinked cryogels.

Evaluation of surface/interface-related physicochemical and microstructural properties of gelatin 3D scaffolds, and their influence on fibroblast growth and morphology.

This article present new insights in complex relation between surface- and interface-related physicochemical properties and microstructuring of three-dimensional (3D) gelatin scaffolds, being fabricated by simultaneous temperature-controlled freeze-thawing cycle and in situ cross-linking using variable conditions (pH) and molarity of carbodiimide reagents, on the seeding and growth of fibroblast cells with subsequent tracking of their spreading and morphology. Rarely populated cells with rounded morphology and small elongations are observed on negative charge-rich scaffold surface with a lower cross-linking degree (CD), and consequently higher molecular mobility and availability of cell-recognition sequences, in comparison with the prominently elongated and densely populated cells on a positively charged scaffold's surface with higher CD and low mobility. Surface microstructure effect was demonstrated by cell vacuolization and their pure intercommunication being present on scaffold's bottom side with smaller pores (25 ± 19 µm) and pore wall thickness (9 ± 5 µm), over the air-exposed side with twice bigger pores (56 ± 38 µm) and pore wall thicknesses (12 ± 6 µm).

Biocatalytic response of multi-layer assembled collagen/hyaluronic acid nanoengineered capsules.

Biodegradable hollow capsules filled with fluorescently labelled bovine serum albumin (BSA) as a model drug were prepared via layer-by-layer (LbL) self-assembly of type-I collagen (COL) and hyaluronic acid (HA) using calcium carbonate micro-particles and co-precipitation method. Capsules loaded with fluorescein isothiocyanate (FITC)-BSA, tetramethylrhodamin isothiocyanate (TRITC)-BSA or Alex-Fluor-488-BSA, respectively, were characterised before and after core removal using Confocal Laser Scanning Microscopy (CLSM), whilst the morphologies of individual hollow capsules were assessed using Atomic Force Microscopy (AFM). The sustained release of the encapsulated FITC-BSA protein was attained using enzymatic degradation of the capsule shells by collagenase.

Use of polysaccharide based surfactants to stabilize organically modified clay particles aqueous dispersion.

Pure as well as organically modified clay minerals are widely applied particles in different research areas. For the incorporation of hydrophobic organically modified clay particles into the hydrogel matrix, a stable aqueous dispersion must be prepared. In this article we report on the stabilization of aqueous dispersions of hydrophobic organically modified clay particles by using a non-ionic polysaccharide-based surfactant system-Inutec SP1 (based on chicory inulin).

Generalized indirect Fourier transformation as a valuable tool for the structural characterization of aqueous nanocrystalline cellulose suspensions by small angle X-ray scattering.

Small angle X-ray scattering (SAXS) is employed to characterize the inner structure and shape of aqueous nanocrystalline cellulose suspensions using the generalized indirect Fourier transformation (GIFT). The use of the GIFT approach provides a single fitting procedure for the determination of intra- and interparticle interactions due to a simultaneous treatment of the form factor P(q) and the structure factor S(q). Moreover, GIFT allows for the determination of particle charges and polydispersity indices.

Homogeneous and heterogeneous methods for laccase-mediated functionalization of chitosan by tannic acid and quercetin.

Homogeneous and heterogeneous methods for functionalization of chitosan with quercetin or tannic acid using laccase from Trametes versicolor is presented, yielding a bio-based product with synergistic antioxidant and antimicrobial properties. HPLC-SEC analysis and cyclic voltammetry kinetic studies showed that laccase catalyzes the oxidation of quercetin to electrophilic o-quinones, which undergo to an oligomer/polymer-forming structures. On the other hand, tannic acid was converted into gallic acid, its dimers, partially gallic acid esterified glucose and glucose, when exposed to laccases.

Preparation, characterization, and in vitro enzymatic degradation of chitosan-gelatine hydrogel scaffolds as potential biomaterials.

The crosslinking of chitosan (CHT) and gelatin (GEL) accomplished with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) was investigated and optimized in relation to hydrogels stability by varying the CHT/GEL mass ratio and the EDC/NHS molar ratio at different and constant EDC concentrations. Hydrogels were also fabricated in the presence of α-tocopherol to assess the release mechanism of a lipophilic drug from a highly-hydrophilic CHT/GEL hydrogel network. Alterations in the physico-chemical properties of hydrogels were characterized by differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR), and their biostability was studied within a simulated body-fluid solution (PBS of pH 7.