Particle size and concentration of poly(epsilon-caprolactone) and adipate modified starch blend on mineralization in soils with differing textures

The objective of this study was to evaluate the effect of particle size and concentration of poly(F.-caprolactone) and adipate modified starch blend on mineralization in soils with differing textures, comparing it with polyethylene under the same experimental conditions. Two soil types were used: a Kandiudalfic Eutrudox with a clayey texture and an Arenic Hapludult with a sandy texture. The two different plastic specimens were incorporated in the form of plastic films with three increasing particle sizes and six doses, from 0 to 2.5 mg C g(-1) soil. Each plastic dose was incorporated into 200 g of soil placed in a hermetically closed jar at 28 degrees C, and incubated for a 120-day period to determine CO(2) evolution. Once again it was confirmed that polyethylene is almost non-biodegradable, in contrast to PCL/S, which can be defined as a biodegradable material. Soil texture affected the mineralization kinetics of the plastic specimens, with higher values for the clayey soil. No changes in soil microbial biomass-C or -N were observed by adding polyethylene and PCL/S to the soil. Also, no significant differences were observed on seed emergence and development of rice seedlings (Oryza sativa L.) in plastic modified soil. (C) 2009 Elsevier Ltd. All rights reserved.

Enhanced fibroblast adhesion and proliferation on electrospun fibers obtained from poly(isosorbide succinate-b-L-lactide) block copolymers

Block copolymers containing isosorbide succinate and L-lactic acid repeating units with different mass compositions were synthesized in two steps: bulk ring-opening copolymerization from L-lactide and poli(isosorbide succinate) (PIS) preoligomer, in the presence of tin(II) 2-ethylhexanoate as catalyst. followed by chain extension in solution by using hexamethylene diisocyanate. Poly(L-lactide) (PLLA) and a chain extension product from PIS were also obtained, for comparison. SEC, (1)H and (13)C NMR, MALDI-TOFMS, WAXD, DSC, TG, and contact angle measurements were used in their characterization. The incorporation of isosorbide succinate into PLLA main backbone had minor effect on the thermal stability and the T(g) of the products. However, it reduced the crystallinity and increased the surface energy in relation to PLLA. Nonwoven mats of the block copolymers and PLLA obtained by electrospinning technique were submitted to fibroblasts 3T3-L1 cell culture. The copolymers presented enhanced cell adhesion and proliferation rate as revealed by MTT assay and SEM images. (C) 2009 Elsevier Ltd. All rights reserved.

Influence of Urea, Isopropanol, and Propylene Glycol on Rutin In Vitro Release from Cosmetic Semisolid Systems Estimated by Factorial Design

Rutin, one of the major flavonoids found in an assortment of plants, was reported to act as a sun protection factor booster with high anti-UVA defense, antioxidant, antiaging, and anticellulite, by improvement of the cutaneous microcirculation. This research work aimed at evaluating the rutin in vitro release from semisolid systems, in vertical diffusion cells, containing urea, isopropanol and propylene glycol, associated or not, according to the factorial design with two levels with center point. Urea (alone and in association with isopropanol and propylene glycol) and isopropanol (alone and in association with propylene glycol) influenced significant and negatively rutin liberation in diverse parameters: flux (g/cm2.h); apparent permeability coefficient (cm/h); rutin amount released (g/cm2); and liberation enhancement factor. In accordance with the results, the presence of propylene glycol 5.0% (wt/wt) presented statistically favorable to promote rutin release from this semisolid system with flux = 105.12 8.59 g/cm2.h; apparent permeability coefficient = 7.01 0.572 cm/h; rutin amount released = 648.80 53.01 g/cm2; and liberation enhancement factor = 1.21 0.07.

Separation and partitioning of Green Fluorescent Protein from Escherichia coli homogenate in poly(ethylene glycol)/sodium-poly(acrylate) aqueous two-phase systems

The partitioning of Green Fluorescent Protein (GFP) in poly(ethylene glycol)/Na-poly(acrylate) aqueous two-phase systems (PEG/NaPA-ATPS) has been investigated. The aqueous two-phase systems are formed by mixing the polymers with a salt and a protein solution. The protein partitioning in the two-phase system was investigated at 25 degrees C. The concentration of the GFP was measured by fluorimetry. It was found that the partitioning of GFP depends on the salt type, pH and concentration of PEG. The data indicates that GFP partitions more strongly to the PEG phase in presence of Na2SO4 relative to NaCl. Furthermore, the GFP partitions more to the PEG phase at higher pH. The partition to the PEG phase is strongly favoured in systems with larger tie-line lengths (i.e. systems with higher polymer concentrations). The molecular weight of PEG is important since the partition coefficient (K) of GFP gradually decreases with increasing PEG size, from K ca. 300-400 for PEG 400 to K equal to 1.19 for PEG 8000. A separation process was developed where GFP was separated from a homogenate in two extraction steps: the GFP is first partitioned to the PEG phase in a PEG 3000/NaPA 8000 system containing 3 wt% Na2SO4, where the K value of GFP was 8. The GFP is then re-extracted to a salt phase formed by mixing the previous top-phase with a Na2SO4 solution. The K-value of GFP in this back-extraction was 0.22. The total recovery based on the start material was 74%. (c) 2008 Elsevier B.V. All rights reserved.

Protein partitioning in poly(ethylene glycol)/sodium polyacrylate aqueous two-phase systems

The partition of hemoglobin, lysozyme and glucose-6-phospate dehydrogenase (G6PDH) in a novel inexpensive aqueous two-phase system (ATPS) composed by poly(ethylene glycol) (PEG) and sodium polyacrylate (NaPA) has been studied. The effect of NaCl and Na2SO4, pH and PEG molecular size on the partitioning has been studied. At high pH (above 9), hemoglobin partitions strongly to the PEG-phase. Although some precipitation of hemoglobin occurs, high recovery values are obtained particularly for lysozyme and G6PDH. The partitioning forces are dominated by the hydrophobic and electrochemical (salt) effects, since the positively charged lysozyme and negatively charged G6PDH partitions to the non-charged PEG and the strongly negatively charged polyacrylate enriched phase, respectively. (c) 2007 Elsevier B.V. All rights reserved.

A convergent approach for the generation of dendrimers containing the [Ru3O(CH3COO)(6)] electroactive core

We report on a convergent approach for the generation of dendrimers containing the [Ru3O(aC)(6)] electroactive core, of great interest as multielectron transfer catalysts. The proposed strategy is based on the generation of the trimeric complex [(Ru3O(ac)(6)(4-pic)(2)(pz))2-mu(2)-Ru3O(ac)(6)(CH3OH)](3+) (ac = acetate, 4-pic = 4-methylpyridine, pz = pyrazine). In this complex, the labile CH3OH ligand can be displaced by the bridging pyrazine ligand of [Ru3O(ac)(6)(pz)3](0), leading to the self-assembly of the [{[Ru3O(ac)(6)(4-pic)(2)(pz)](2)-mu(2)-Ru3O(ac)(6)(pz)}(3)- mu(3)-Ru3O(ac)(6)](n+) dendrimer containing 30 ruthenium atoms. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).

(-)-Hinokinin-loaded poly(d,l-lactide-co-glycolide) microparticles for Chagas disease

The (-)-hinokinin display high activity against Trypanosoma cruzi in vitro and in vivo. (-)-Hinokinin-loaded poly(d,l-lactide-co-glycolide) microparticles were prepared and characterized in order to protect (-)-hinokinin of biological interactions and promote its sustained release for treatment of Chagas disease. The microparticles contain (-)-hinokinin were prepared by the classical method of the emulsion/solvent evaporation. The scanning electron microscopy, light-scattering analyzer were used to study the morphology and particle size, respectively. The encapsulation efficiency was determined, drug release studies were kinetically evaluated, and the trypanocidal effect was evaluated in vivo. (-)-Hinokinin-loaded microparticles obtained showed a mean diameter of 0.862 A mu m with smooth surface and spherical shape. The encapsulation efficiency was 72.46 A +/- 2.92% and developed system maintained drug release with Higuchi kinetics. The preparation method showed to be suitable, since the morphological characteristics, encapsulation efficiency, and in vitro release profile were satisfactory. In vivo assays showed significant reduction of mice parasitaemia after administration of (-)-hinokinin-loaded microparticles. Thus, the developed microparticles seem to be a promising system for sustained release of (-)-hinokinin for treatment of Chagas disease.

Amphotericin B in poly(lactic-co-glycolic acid) (PLGA) and dimercaptosuccinic acid (DMSA) nanoparticles against paracoccidioidomycosis

The present study reports on the preparation and testing of a desoxycholate amphotericin B (D-AMB) sustained delivery system based on poly(lactic-co-glycolic acid) (PLGA) and dimercaptosuccinic acid (DMSA) polymeric blends (Nano-D-AMB) aimed at reducing the number of AMB administrations required to treat mycosis. BALB/c mice were infected with the yeast Paracoccidioides brasiliensis intravenously to mimic the chronic form of paracoccidioidomycosis. At 30 days post-infection, the animals were treated with Nano-D-AMB [6 mg/kg of encapsulated D-AMB, intraperitoneally (ip), interval of 72 h] or D-AMB (2 mg/kg, ip, interval of 24 h). Drug efficacy was investigated by the fungal burden recovery from tissues. Toxicity was assessed by renal and hepatic biochemical parameters, physical appearance of the animals and haematological investigation. The control groups used were non-infected and the infected mice mock treated with PBS. Nano-D-AMB presented results comparable to free D-AMB, with a marked antifungal efficacy. The Nano-D-AMB-treated group presented lower loss of body weight and absence of stress sign (piloerection and hypotrichosis) observed after D-AMB treatment. No renal [blood urea nitrogen (BUN), creatinine] or hepatic (pyruvic and oxalacetic glutamic transaminases) biochemical abnormalities were found. The micronucleus assay showed no significant differences in both the micronucleus frequency and percentage of polychromatic erythrocytes for Nano-D-AMB, indicating the absence of genotoxicity and cytotoxic effects. The D-AMB-coated PLGA-DMSA nanoparticle showed antifungal efficacy, fewer undesirable effects and a favourable extended dosing interval. Nano-D-AMB comprises an AMB formulation able to lessen the number of drug administrations. Further studies would elucidate whether Nano-D-AMB would be useful to treat systemic fungal infections such as paracoccidioidomycosis, candidiasis, aspergillosis and cryptococcosis.

Synthesis and characterization of ternary hybrid material based on poly-o-methoxyaniline and poly(ethylene oxide) in mesostructured V(2)O(5)

New hybrid composites based on mesostructured V(2)O(5) containing intercalated poly(ethylene oxide), poly-o-methoxyaniline and poly(ethylene oxide)/poly-o-methoxyaniline were prepared. The results suggest that the polymers were intercalated into the layers of the mesostructured V(2)O(5). Electrochemical studies showed that the presence of both polymers in the mesostructured V(2)O(5) (ternary hybrid) leads to an increase in total charge and stability after several cycles compared with binary hybrid composites. This fact makes this material a potential component as cathode for lithium ion intercalation and further, a promising candidate for applications in batteries.

Solid-phase microextraction using poly(pyrrole) film and liquid chromatography with UV detection for analysis of antidepressants in plasma samples

Poly(pyrrole) (PPY) coating was prepared on a stainless-steel (SS) wire for solid-phase microextraction (SPME) by electrochemical deposition (cyclic voltammetric). The PPY was evaluated by analyzing new-generation antidepressants (mirtazapine, citalopram, paroxetine, duloxetine, fluoxetine, and sertraline) in plasma sample by SPME and liquid chromatography with UV detection (LC-UV). The effect of electrolyte Solution (lithium perchlorate or tetrabutylammonium perchlorate) and the number of cycles (50, 100 or 200) applied during the polymerization process on the SPME performance was evaluated. Important factors in the optimization of SPME efficiency such as extraction time, temperature, pH, influence of plasma proteins on sorption mechanisms, and desorption conditions are discussed. The SPME-PPY/LC method showed to be linear in concentrations ranging from the limit of quantification (LOQ) to 1200 ng mL(-1). The LOQ values range from 16 to 25 ng mL-1. The inter-day precision of the SPME-PPY/LC method presented coefficient of variation (CV) lower than 15%. Based on analytical validation results, the SPME-PPY/LC methodology showed to be adequate for antidepressant analysis, from therapeutic to toxic levels. In order to evaluate the proposed method for clinical use, the SPME-PPY/LC method was applied to the analysis of plasma samples from elderly depressed patients. (c) 2009 Elsevier B.V. All rights reserved,

Spectroelectrochemistry and investigation of charge transport mechanisms of iron poly(pyridyl) redox polymers

In this work, we describe the characterization of the complex [Fe(tpy-NH2)(2)](PF6)(2) (tpy-NH2 = bis[4`-(3-aminophenyl)-2, 2`:6`,2 ``-terpyridine]. The complex was oxidatively electropolymerized on glassy.-carbon electrodes in CH3CN/0.1 M tetraethylammonium perchlorate (TEAP) to generate polymer films that exhibit reversible oxidative electrochemical behavior in a wide potential range (0.0-1.6 V), as well as high conductivity and stability/durability. In situ spectrocyclic voltammetry of this modified electrode was carried out on a photodiode array spectrophotometer attached to a potentiostat, which provided UV-Vis absorption spectra of the redox species during the potential sweep. We determined charge transport parameters as a function of time and thickness of the modified electrode, and the results showed that poly-[[Fe(tpy-NH2)(2)](2+)](n) can be made to exhibit three regimes of charge transport behavior by manipulation of the film thickness and the experimental time-scale. Morphological characterization of the film was provided by atomic force microscopy. (C) 2008 Elsevier Ltd. All rights reserved.

Development of nanostructured bioanodes containing dendrimers and dehydrogenases enzymes for application in ethanol biofuel cells

This paper describes the use of the electrostatic layer-by-layer (LbL) technique for the preparation of bioanodes with potential application in ethanol/O(2) biofuel cells. More specifically, the LbL technique was employed for immobilization of dehydrogenase enzymes and polyamidoamine (PAMAM) dendrimers onto carbon paper support. Both mono (anchoring only the enzyme alcohol dehydrogenase, ADH) and bienzymatic (anchoring both ADH and aldehyde dehydrogenase, AldDH) systems were tested. The amount of ADH deposited onto the Toray (R) paper was 95 ng cm(-2) per bilayer. Kinetic studies revealed that the LbL technique enables better control of enzyme disposition on the bioanode, as compared with the results obtained with the bioanodes prepared by the passive adsorption technique. The power density values achieved for the mono-enzymatic system as a function of the enzyme load ranged from 0.02 to 0.063 mW cm(-2) for the bioanode containing 36 ADH bilayers. The bioanodes containing a gas diffusion layer (GDL) displayed enhanced performance, but their mechanical stability must be improved. The bienzymatic system generated a power density of 0.12 mW cm(-2). In conclusion, the LbL technique is a very attractive approach for enzyme immobilization onto carbon platform, since it enables strict control of enzyme disposition on the bioanode surface with very low enzyme consumption. (C) 2010 Elsevier B.V. All rights reserved.

Development of novel bioanodes for ethanol biofuel cell using PAMAM dendrimers as matrix for enzyme immobilization

This paper describes the preparation and application of a novel bioanode for use in ethanol/O(2) biofuel cells based upon immobilization of alcohol dehydrogenase (ADH) and polyamidoamine (PAMAM) dendrimers onto carbon cloth platforms. The power density measurements indicated a direct relationship between the amount of anchored ADH and the anode power values, which increased upon enzyme loading. The power density values ranged from 0.04 to 0.28 mW cm(-2), and the highest power density was achieved with the bioanode prepared with 28 U of ADH, which provided a power density of 0.28 mW cm(-2) at 0.3 V. The latter power output values were the maximum observed, even for higher enzyme concentrations. Stability of the bioanodes was quite satisfactory, since there was no appreciable reduction of enzymatic activity during the measurements. The method of bioanode preparation described here has proven to be very effective. The PAMAM dendrimer represents a friendly environment for the immobilization of enzymes, and it is stable and capable of generating high power density compared to other immobilization methods. (C) 2010 Elsevier B.V. All rights reserved.

Synthesis and Characterization of Semi-Interpenetrating Networks Based on Poly(dimethylsiloxane) and Poly(vinyl alcohol)

Semi-interpenetrating networks (Semi-IPNs) with different compositions were prepared from poly(dimethylsiloxane) (PDMS), tetraethylorthosilicate (TEOS), and poly (vinyl alcohol) (PVA) by the sol-gel process in this study. The characterization of the PDMS/PVA semi-IPN was carried out using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and swelling measurements. The presence of PVA domains dispersed in the PDMS network disrupted the network and allowed PDMS to crystallize, as observed by the crystallization and melting peaks in the DSC analyses. Because of the presence of hydrophilic (-OH) and hydrophobic (Si-(CH(3))(2)) domains, there was an appropriate hydrophylic/hydrophobic balance in the semi-IPNs prepared, which led to a maximum equilibrium water content of similar to 14 wt % without a loss in the ability to swell less polar solvents. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 158-166, 2010

Pt/TiO(2)/poly(vinyl sulfonic acid) Layer-by-Layer Films for Methanol Electrocatalytic Oxidation

One major challenge for the widespread application of direct methanol fuel cells (DMFCs) is to decrease the amount of platinum used in the electrodes, which has motivated a search for novel electrodes containing platinum nanoparticles. In this study, platinum nanoparticles were electrodeposited on layer-by-layer (LbL) films from TiO(2) and poly(vinyl sulfonic) (PVS), by immersing the films into a H(2)PtCl(6) solution and applying a 100 mu A current during different electrode position times. Scanning tunnel microscopy (STM) and atomic force microscopy (AFM) images showed increased platinum particle size and electrode roughness for increasing electrodeposition times. The potentiodynamic profile of the electrodes indicated that oxygen-like species in 0.5 mol L(-1) H(2)SO(4) were formed at less positive potentials for the smallest platinum particles. Electrochemical impedance spectroscopy measurements confirmed the high reactivity for the water dissociation and the large amount of oxygen-like species adsorbed on the smallest platinum nanoparticles. This high oxophilicity of the smallest nanoparticles was responsible for the electrocatalytic activity of Pt-TiO(2)/PVS systems for methanol electrooxidation, according to the Langmuir-Hinshelwood bifunctional mechanism. Significantly, the approach used here combining platinum electrodeposition and LbL matrices allows one to both control the particle size and optimize methanol electrooxidation, being therefore promising for producing membrane-electrode assemblies of DMFCs.