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In the present work, polylactic acid (PLA), elastin and gelatin fibers, containing clindamycin, were prepared to test their potential application as wound dressings. They underwent release studies to determine the mechanism of drug release through mathematical models. The fibers have a homogeneous morphology, without pores. The studies of FTIR and thermal analysis corroborate the presence of each of the components in the fibers; the results of the feasibility tests showed encouraging percentages with a viability of 82% after 7 days of direct contact of the HUVEC cells with the membranes. Similarly, cell adhesion assays show the presence of viable and stretched cells on the fibers, the tendency of the cells to position themselves on the fibers and follow this conformation was observed. On the other hand, studies of antimicrobial activity against S. aureus show us that in fibers loaded with clindamycin they have inhibition halos greater than 8 mm.

The extensive use of petroleum-based plastics has led to serious environmental problems worldwide. A viable alternative is to replace these polymers with those that are biodegradable. Polylactic acid (PLA) is a biodegradable polymer with properties that are similar to petroleum-based polymers. However, it has some drawbacks such as brittleness, poor impact strength, low heat distortion, and poor difficulties in thermal stability during processing. In this study, we describe the use of modified jute fibres to reinforce the PLA polymer matrix in order to improve its adhesion. Biocomposites of PLA and cut jute fibres (CJF) were prepared by extrusion. The CJF were modified using three different physical and chemical pretreatments (alkaline, maleic anhydride functionalization, and gamma irradiation). The results showed improvement in the mechanical, thermal, structural, and morphological properties of PLA biocomposites with 10% wt. CJF that were subjected to gamma irradiation at 50 kGy. The biocomposites developed could be used for rigid food packaging and are a good alternative for reducing domestic dependence on petroleum-based thermoplastics.

The development of Green-based methods for preparing polypyrrole (PPy)-containing materials with optimal electroactivity still remains a challenge. We herein report a new green approach for the preparation of PPy/carbon nanotube/alginate multifunctional nanocomposites through H2O2 oxidation in micellar medium. The polymerization conditions were systematically varied to optimize the reaction yield and the material electroconductivity. The pre-polymerization emulsion system was studied by contact angle measurements and dynamic light scattering. The results of zeta potential characterization, field-emission scanning electron and atomic force microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy are discussed in detail, and a consistent mechanism for the nanocomposite formation is proposed. Interestingly, the synergistic combination of pristine carbon nanotubes and the alginate improves the conductivity and stability of PPy-based colloids. Furthermore, a metoprolol-loaded platform, obtained by the confinement of the synthesized nanocomposite into an alginate network, revealed a cumulative release lesser than 10% after five hours of delivery under passive conditions. This behavior seems to be promising to overcome the undesired burst release in stimulus-controlled drug delivery.

Polyethylene/poly (lactic acid)/chitosan films, with and without poly (ethylene-g-maleic anhydride) (PEgMA) as compatibilizer, were prepared by extrusion and the degradation behavior under different times of standard weathering conditions was analyzed. The materials were characterized by means of infrared spectroscopy, scanning electron microscopy, tensile strength, differential scanning calorimetry and thermogravimetric analysis. It was demonstrated that blends of synthetic and natural polymers have a higher susceptibility to degradation in comparison to neat polyethylene and poly (lactic acid) films. Additionally, it is found that the incorporation of PEgMA into the extruded films apparently favored the polymer degradation, as it deduced from the fall of the mechanical properties when the films are exposed to accelerated weathering simulation.

Optimal usage of urea-based fertilizers can increase their use efficiency and reduce pollution. A new alternative for prolonged-release (PR) urea based on wheat-gluten (WG) membranes obtained by electrospinning was studied. The effect of pH and temperature on the release rate of urea and its transport mechanisms were evaluated. At pH 4, 7, and 10, the equilibration times obtained were 1, 3, and 5 h, respectively. Additionally, at a higher temperature, a larger amount of urea was released into the medium. The Ritger–Peppas model suggests that with pH 4 and pH 10, at 25 °C, there is an anomalous diffusion mechanism. On the other hand, the remainder of the release conditions tested showed a release mechanism of urea by simple diffusion. According to the results, a potential application of these wheat-gluten membranes on the release system of urea for soils with pH 7 and soil temperatures between 25 and 40 °C is proposed.

Among the natural fibers, jute stands out for its characteristics. However, the adhesion between the fibers and the polymer matrix is limited and, therefore, physicochemical changes to the ...

This paper presents the selective adsorption of bromine-metallic complexes of Au and Ag on composite membranes, as well as the desorption process and redoping of the conducting polymers. The polyaniline (PANI) and polypyrrole (PPy) membranes exhibited relevant adsorption properties. 72% for gold and 98% for silver with PANI, 50% for gold and 97% for silver with PPy, in bromine complexes. The adsorption capabilities of the composite membranes were attributed to the ion exchange between the dopant and the AuBr 4 − or AgBr 2 − complexes. Both materials fitted to a Langmuir isotherm. PANI-based membranes reached 31.4% of gold and 54.4% of silver desorption whereas PPy-based membranes reached 54% of gold and 28.8% of silver. Redoping studies suggested the potential reuse of the PANI-based membranes at least for six cycles of the adsorption/desorption process. The preparation of cellulose acetate membranes modified with poly (acrylic acid) and triphenyl phosphate and coated with the conducting polymers, PANI or PPy was in accordance to our previously reported method. The composite membranes were characterized by FT-IR, scanning electron microscopy, electrical conductivity measurements, I–V, mechanical tests, contact angle measurements, XRD and energy disperse spectroscopy. The novelty of the present work is the combination of electroconductive polymers, for the recovery of metals, and bromide as a leachate, less harmful than the traditionally used leachers.

Development of microparticles based on natural polymers has been of interest for researchers due to their applications, such as release systems. Currently, one of the problems presented by agriculture worldwide is the loss of fertilizers, i.e., urea, causing environmental pollution and high costs. The aim of this work was to develop microparticles of wheat glutenins by means of electrospray technique, with potential application as a urea controlled-release system in agricultural soils. The microparticles of wheat glutenins were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). In addition, a release kinetic test was performed to evaluate the possible behaviour of wheat-glutenin microparticles in agricultural soils with pH 4, 7 and 10, using buffers as the release medium. TGA indicated that microparticle stability was $${>}100{^{\circ }}\hbox {C}$$ , while FT-IR demonstrated the existence of physical interactions between urea and wheat glutenins. The kinetic tests showed the possible behaviour of the controlled-release fertilizer at pH 4, 7 and 10; rapid release at acidic pH and a decrease in release time at basic pH. With these results, we can conclude that the urea-charged wheat-glutenin microparticles can function as a controlled-release fertilizer in agricultural soils.

Polyacrylamide (PAAm) hydrogel containing nanofibers of polyaniline (PANI) has been prepared in order to evaluate it as electric stimuli-responsive material. Amoxicillin was loaded onto chemically synthesized PANI nanofibers of large-aspect-ratio. Composite hydrogel was obtained by the in situ incorporation of amoxicillin-loaded PANI during polymerization and reticulation of acrylamide. TEM images of cross sections of PAAm/amoxicillin-loaded PANI composite revealed a continuous 3D nanofiber network of PANI supported by the hydrogel matrix. The antibiotic molecules were accurately released (or sustained) from composite hydrogel in response to application (or removal) of cathodic electrical stimulation. In vitro cytotoxicity evaluation of composite hydrogel extract on mouse subcutaneous connective tissue has shown cell viability higher than 80%. The tuning release profile and minimal toxicity of the material evidenced its potential for electrically controlled drug delivery applications such as implantable devices and transdermal drug delivery systems.

We report, for the first time, the use of a bile salt, the sodium taurocholate (Tch), as a surface-active agent in the emulsion synthesis of electroactive polypyrrole (PPy) nanoparticles. PPy was obtained under mild and environmentally friendly conditions, using hydrogen peroxide (H2O2) as a green oxidant. The combined addition of a non-ionic surfactant, Tween 20 (Tw), was also studied. The electrical, structural, morphological, and colloidal properties of reaction products were analyzed in detail to find the best conditions of synthesis. The pre-polymerization emulsion systems were studied by osmometric measurements, isothermal titration calorimetry (ITC), and dynamic light scattering (DLS). A consistent mechanism of nucleation and growth of PPy colloids is proposed. The Tch acts as an emulsifier of the reaction media, a doping agent of oxidized chain of PPy, and a stabilizer of the resulting colloids. The main advantage of this work is the preparation of polymer colloids through a completely green alternative route, which could open up new possibilities for obtaining nanoparticles through an effective and non-toxic method.

Optimal conditions for the preparation of a composite material of fibers of cellulose acetate (CA) and poly(vinyl pyrrolidone) (PVP), containing epicatechin (Epic) within the fiber CA/PVP–Epic/CA, were found. The morphology and physical/chemical properties of the fibrous membranes containing CA, PVP, and epicatechin were characterized using FTIR spectroscopy, thermal analysis, SEM, TEM, and natural weathering. Also, mechanical characterization of the fibers showed that tensile strength of the membrane was not affected by the presence of epicatechin within the fiber as compared with fibers without epicatechin. The effect of the medium on the release rate of epicatechin was also studied. The amount of epicatechin release was higher in water, 79.6%, and 31% in MesenCult medium. These results showed that these composite materials are recommended for cardiac tissue engineering; furthermore, using these materials allows precise release of the epicatechin in the damaged tissue.

The use of mixtures of synthetic and natural polymers is a potential option to reduce the pollution by plastic waste. In this work, the method for the chemical modification of chitosan with poly(lactic acid) was developed, then, the preparation of films of blends of polyethylene and chitosan-poly(lactic acid) produced by an extrusion method using polyethylene-graft maleic anhydride as a compatibilizer. It was possible to obtain films with a maximum content of 20 wt% and 30 wt%, chitosan, with and without compatibilizer, respectively. Scanning electron microscope (SEM) analysis showed a homogeneous surface on all films. The addition of the compatibilizer had a significant effect on the mechanical properties of the films, such as an increase in Young’s modulus and a decrease in the elongation at break, additionally, the compatibilizer promotes thermal degradation in a single step and gives the film a slight increase in thermal resistance. These results are attributed to an improved interaction in the interface of polyethylene and chitosan-poly(lactic acid), promoted by the compatibilizer.

Novel films of polyethylene and chitosan were obtained using extrusion. These polymers have interesting properties, and processing them with methods that are of high use in the industry, such as the extrusion method, can have a significant effect on the potential applications of these materials. The individual materials were thermally characterized; after this, extruded films of low density polyethylene and chitosan mixtures were prepared with the addition of polyethylene-graft-maleic anhydride as a compatibilizer for the blends, and glycerol, as a plasticizer for chitosan. The use of compatibilizer and plasticizer agents improved the processability and compatibility of the mixtures, as well as their mechanical properties, as revealed by mechanical property measurements and scanning electron microscopy. It was possible to prepare blends with a maximum chitosan content of 20 wt%. The material stiffness increased with the increase of chitosan in the sample. FTIR studies revealed the existence of an interaction between the compatibilizer and chitosan.

Hybrid submicro/nanostructures of polyaniline (PANI) and l -glutamic acid (GA) were chemically prepared with the addition of ammonium persulfate (APS) as the oxidant. Different GA and APS concentrations were investigated in order to obtain the optimal conditions for the formation of high aspect ratio structures. TEM, electrical and XPS characterizations revealed that at monomer:amino acid:oxidant molar ratio of 1:0.25:1, the PANI presented a fibrillar morphology with diameters in submicro and nanometric scale, the structures were coating with the GA and the GA doped the PANI backbone. The fibrillar structures of GA coated-PANI efficiently adsorbed therapeutic doses of amoxicillin and controlled release of the drug can be achieved in function of pH environment, with a maximum cumulative release of 98% at pH 9 within 48 h.

The preparation of composites of synthetic and natural polymers represent an interesting option to combine properties, in this manner, polypropylene and chitosan extruded films using a different proportion of components and polypropylene-graft-maleic anhydride (PPgMA) as compatibilizer were prepared. The effect of the content of the biopolymer in the polypropylene (PP) matrix, the addition of compatibilizer, and the particle size on the properties of the composites was analyzed using characterization by fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), tensile strength, and contact angle, finding that in general, the addition of the compatibilizer and reducing the particle size of the chitosan, favored the physicochemical and morphological properties of the films.

The preparation, characterization, and photocatalytic activity evaluation of three hybrid fibrous materials composed mainly by poly(methyl methacrylate) (PMMA), methyl methacrylate (MMA): 3-(trimethoxysilyl) propyl methacrylate (TMSPM): titanium butoxide (TBT), TiO2 nanoparticles (NPTiO2), and TiO2 nanowires (NWTiO2) is studied. Two types of fibeŕs structures were prepared, single and core-shell structures. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis showed both structures, single and core-shell, as well as the inorganic phase were dispersed in the hybrid fibers. Infrared spectroscopic analysis (FT-IR) and thermal analysis showed the organic and inorganic components, as well as the weight percentage of the inorganic phase present in hybrid fibers. The photocatalytic activity of the hybrid fibers class I and II showed that the best photodegradative efficiency for methylene blue in aqueous solution (2.9 × 10−5 M) was 95%, provided by PMMA—10 wt % NPTiO2. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44334.

The optimal conditions for the preparation of a composite material of fibers of cellulose acetate (CA), poly (vinyl pyrrolidone) (PVP), containing amoxicillin (Amoxi) within the fiber, CA/PVP-Amoxi/CA, were found. The geometrical, physical–chemical and thermal properties of the fibrous membranes containing CA, PVP and amoxicillin were characterized using FTIR spectroscopy, thermal analysis, SEM and TEM. Also, mechanical characterization of the fibers showed that the tensile strength of the membrane is not affected by the presence of amoxicillin within the fiber as compared with fibers without amoxicillin; however, the rigidity of the membrane decreases by approximately 45%. The effect of the pH on the release rate of amoxicillin was also studied. The amount of amoxicillin release and the k value increased with an increasing pH, from 61% for a pH 3.0 to 79% at pH 7.2, with k values of 0.2120 and 0.2609 respectively. An empirical model for the amoxicillin release was studied; the release of amoxicillin is assumed to obey a diffusion mechanism. These composite materials are recommended for solving the problem of possible loss of drug during the process of entrapment in the matrix with potential local application in biological media to treat dental or skin infections.

Cellulose acetate membranes (M1) with controlled thickness were coated with an electroconductive polymer, and the resulting composites were characterized by SEM, XPS, electrical conductivity, and mechanical measurements. A comparative study of M1 coated with polyaniline (PANI) or with polypyrrole (PPy) for adsorption and subsequent desorption of a gold–iodide complex was performed. The PANI-coated M1 (M2) and that coated with PPy (M3) are effective adsorbents for recovery of the AuI2− complex. The adsorption of gold on the membranes was attributed to the exchange between the dopant ions and the AuI2− complex ions. The adsorption equilibrium data fitted the Langmuir isotherm model for both membranes M2 and M3. The desorption of the AuI2− complex with a NH4OH solution 3 M reached 97% for M3 membrane. This study shows a convenient method for the recovery of gold through the use of a complex with iodine without cyanide solutions.

Hydrogels of semi-interpenetrating networks composed of poly(acrylamide) (PAAm) and poly(γ-glutamic acid) (γ-PGA) with different proportions were studied as potential amoxicillin controlled-release devices. The effects of the hydrogels composition, pH, and temperature on the kinetics and final release of amoxicillin were determined in batch experiments. The release kinetic tests were conducted using a buffer solution as the release medium under pH conditions of 3 and 7.2, and temperature of 25, 37, and 45 °C. The final percentage of amoxicillin released from the hydrogels was found to increase with temperature, pH, and the amount of γ-PGA in the hydrogels formulation. Overall, equilibrium conditions in the kinetics experiments were achieved within 240 min of hydrogel–solution contact. The overall rate of amoxicillin release was represented with a two-parameter empirical model as a function of time.

The use of compatibilizers as interfacial agents in composites can offer a convenient way to improve the mechanical properties of immiscible polymer blends. The aim of this article is to illustrate the compatibilization effect of polyethylene-graft-maleic anhydride (PEgMA) in blends of low-density polyethylene (LDPE) and n-dodecylbenzene sulfonate doped polyaniline (PANIDBSA) prepared by extrusion. Films with different compositions of the coupling agent were evaluated with optical spectroscopy and thermomechanical, electrical, mechanical, and morphological techniques. The incorporation of PEgMA into the LDPE/PANIDBSA composites resulted in an improvement of their electrical conductivity and changes in the mechanical and morphological properties of the films. When 5 wt % of the coupling agent was added to a 30 wt % of the polyaniline-containing film, the conductivity increased by more than three orders of magnitude, and the ductility also improved qualitatively. The morphology analysis also indicated that the addition of PEgMA produced a strengthening of the filler–matrix interfacial region. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The optimal conditions for the fibers preparation of cellulose acetate (CA) and poly(vinyl pyrrolidone) (PVP) containing triclosan within the fiber were successfully found; the physicochemical characteristics of these fibrous membranes were corroborated by FTIR spectroscopy, thermal analysis, mechanical tests, SEM , and TEM analysis. The formation of composite fibers of CA and PVP containing triclosan at the core of the fiber was evidenced. A comparative study of the release properties of amoxicillin, epicatechin or triclosan embedded into fibers CA/PVP/CA was performed. As more interactions of the drug with CA or PVP occur, slower release of the drug into the release medium takes place. Regarding the drug delivery system design, it is important to consider the possible molecular interactions between the material components and predict how fast or slow the drug will be delivered into the corresponding medium.

Proteins suffer changes in their tertiary structure when they are immobilized, and enzymatic activity is affected due to the low biocompatibility of some supporting materials. In this work immobilization of lysozyme on carbon nanotubes previously functionalized by microwave irradiation was studied. The effectiveness of the microwave-assisted acid treatment of carbon nanotubes was evaluated by XPS, TEM, Raman and FTIR spectroscopy. The carboxylic modification of nanotube surfaces by this fast, simple and feasible method allowed the physical adsorption and covalent linking of active lysozyme onto the carbonaceous material. Thermal inactivation kinetics, thermodynamic parameters and storage stability were studied for adsorbed and covalent enzyme complexes. A major stability was found for lysozyme immobilized by the covalent method, the activation energy for inactivation of the enzyme was higher for the covalent method and it was stable after 50 d of storage at 4 ?C. The current study highlights the effect of protein immobilization method on the biotechnological potential of nanostructured biocatalysts.

The impact of chitosan on the natural weathering behavior of two blends obtained by mixing either polyethylene (PE) with chitosan or PE, chitosan and polyethylene-graft-maleic anhydride (PEgMA) as a compatibilizer is analyzed. In order to follow the weathering behavior of both the uncompatibilized and compatibilized systems, the blend films are exposed to outdoor conditions for 6 months. The weathering behavior of the films is monitored by mechanical tests, spectroscopic Fourier transform infrared, and morphological analyses at different weathering periods of time. The presence of chitosan in the blends accelerates significantly the degradation of the films. Apparently, PEgMA also accelerates the photo-oxidation rate of the films. This behavior appears to be related to the photo-oxidative instability of maleic anhydride, and also to the better dispersion of chitosan in the PE matrix, which is due to the interactions in the PE/chitosan interface caused by the addition of the compatibilizer. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41045.

Homogeneous and thin porous membranes composed of oriented fibers were obtained from wheat gluten (WG) using the electrospinning technique. SEM micrographs showed an asymmetric structure and some porosity, which, in addition to a small thickness of 40 mm, are desirable characteristics for the membranes’ potential application in release systems. The membranes were loaded with urea to obtain pastilles. FT-IR and DSC studies confirmed the existence of interactions via hydrogen bonding between urea and WG proteins. The pastilles were studied as prolonged-released systems of urea in water. The release of urea during the first 10 min was very fast; then, the rate of release decreased as it reached equilibrium at 300 min, with a total of »98% urea released. TGA analysis showed that the release system obtained is thermally stable up to a temperature of 117 °C. It was concluded that a prolonged-release system of urea could be satisfactorily produced using WG fibers obtained by electrospinning for potential application in agricultural crops.