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The effectiveness of antibiotics toward resistant strains of bacteria has brought serious concerns related to human and animal health. Controlled drug release systems, especially those based on polymer and polymer-based nanostructures appears as a remarkable approach, once they can potentially improve the therapeutic outcomes toward bacterial infections, while requiring lower amounts of drugs. The current study was designed to investigate the incorporation and release profile of a drug loaded in biodegradable electrospun nanofibrous membranes, based on the drug-polymer interactions, as well as its ability to inhibit bacterial growth. For that purpose, nanofibrous membranes of Ecovio® (EC), a polymer blend composed by poly (lactic acid) (PLA)/poly (butylene adipate-co-terephthalate) (PBAT), loaded with different cloxacillin (CLOX) contents were successfully produced via electrospinning technique. Electrospun nanofibers of EC unloaded and loaded with drug presented smooth surface with a mean diameter close to 600 nm. The physical-chemical characterizations by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) confirmed the successful drug encapsulation achieved by electrospinning technique. In vitro studies revealed that the developed drug-loaded nanofibrous membrane was successful in inhibiting S. aureus growth. The cumulative release of drug from EC nanofibrous membranes containing 20% of CLOX was demonstrated to be pH dependent, where the antibiotic release rate was much faster for pH 7.3 than that for pH 5.5. In this way, the mechanism involved in the release could be either Fickian or non-Fickian depending on the pH environment. The simple and efficient strategy presented here to develop antimicrobial nanofibrous membrane make them promising for drug delivery carrier and wound dressing applications.

Blends of zein and poly(vinyl alcohol) (PVAl) were processed in an internal mixer (150oC, 50 rpm) for 5-8 minutes. Glycerol and oleic acid were used as plasticizers. The mixtures obtained were then compression molded and further characterized by Fourier transform infrared spectroscopy (FTIR), water-absorption experiments, mechanical tests, and scanning electron microscopy (SEM). FTIR analysis indicated the existence of hydrogen bonding interactions between zein and PVAl. Tensile tests showed that the addition of PVAl increased the flexibility of the blends. The tensile strength ranged from 1.7 to 5.7 MPa, elongation at break ranged from 2.7 to 32% and Young’s modulus ranged from 433 to 7371 MPa. Water absorption at equilibrium decreased with increasing zein content, which favored a brittle behavior in the zein/PVAl. The blends were immiscible in the composition studied and the presence of voids indicated poor interfacial interaction between the polymers.

In this study, gelatin, a biocompatible, collagen-derived protein, was combined with clove essential oil (CEO) and hydrotalcite ([Mg-Al-CO3]-LDH) nanoplates (D ∼ 100 nm) as an attempt to develop new antimicrobial wound dressings. CEO-loaded gelatin films covering different hydrotalcite contents (0.5–5.0 wt.%) were obtained by solution casting and characterized by light microscopy, FTIR and UV–vis spectroscopies, tensile and optical tests, water contact angle (WCA) determinations, and disc diffusion assays. CEO formed emulsified morphologies with gelatin over the entire hydrotalcite content range. Hydrotalcite contents larger than 2.5 wt.% were key for retain CEO in the gelatin matrix, which ensured antimicrobial activity for the films against Staphylococcus aureus and Escherichia coli. The UV barrier and mechanical properties of gelatin were significantly increased by CEO and further sustained upon hydrotalcite addition. All the composite films were regarded as hydrophilic materials (WCA

Endocrine disruptor compounds (EDCs) are environmental pollutant chemicals that can affect the endocrine system of some organisms. Such compounds are excreted by humans and released into aquatic environments via sewage treatment plant. One example of EDC is 17α-ethinylestradiol (EE2), a synthetic estrogen widely used as oral contraceptive and considered a powerful estrogenic. Although there has been a deep concern about the EDC presence in surface and drinking waters, there are only a few works in the scientific literature regarding EE2 electrochemical detection. Here we present the development of a new nanostructured sensing platform aimed at the electrochemical detection of EE2. The platform was based on a fluorine doped tin oxide (FTO) electrode coated with nanostructured Layer-by-Layer (LbL) films of chitosan/multi-walled carbon nanotubes (Chi/CNTs). The physicochemical properties of the films were evaluated by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical characterization revealed a decrease in the film resistance as the number of bilayers increased from 1 to 3, as a direct consequence of the augment in the amount of conductive material (CNTs). Cyclic voltammetric measurements showed that the three bilayer electrode, namely FTO-(Chi/CNTs) 3 , are suitable to EE2 detection, through an irreversible and adsorption-controlled electrochemical oxidation process. Square Wave Voltammetry (SWV) yielded a linear response for EE2 detection in range from 0.05 to 20 μmol L − 1 , with a detection limit of 0.09 μmol L − 1 (S/N = 3). The sensor showed a good reproducibility with the relative standard deviation (RSD) equal to 3.2% and 6.6% to intra- and inter-electrode, respectively. Furthermore, the sensor platform showed to be suitable to EE2 selective electrochemical detection, with no significant interference from common interfering compounds. The concepts behind the EE2 electrochemical behavior can be potentially harnessed for designing new electrochemical sensors and biosensors with the architecture described here.

In this work, thermoplastic starch (TPS)–clay bionanocomposites were obtained by an innovative methodology using a combination of methodologies commonly used in the composites and nanocomposites preparations. The main objectives or novelties were to confirm efficiency of the processing methodology by field emission gun scanning electron microscopy and investigate the effect of clay content on the spectroscopic, bulk and surface hydrophilic/hydrophobic properties of these bionanocomposites. Raman and FTIR spectroscopies confirmed the changes in the spectroscopic properties of the TPS bionanocomposites with the addition of the clay materials. Water absorption and contact angle measurements were also used to analyze the effect of the clay content on the hydrophilic properties of the TPS bionanocomposites. The results also showed that the addition of the cloisite-Na + clay increased the bulk and surface hydrophobicities of the TPS matrix, which may increase its industrial application, particularly in manufacturing of food containers.

Solution blow spinning (SBS) is a novel technology feasible to produce nanostructured polymeric membranes loaded with active agents. In the present study, nanofibrous mats of poly(lactic acid) (PLA) loaded with progesterone (P4) were produced by SBS at different P4 concentrations. The spun membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The in vitro releasing of P4 was evaluated using high-performance liquid chromatography (HPLC). Interactions between progesterone and PLA were confirmed by rheological measurements of the PLA/P4 solutions and in the spun mats by microscopy (SEM), thermal (DSC) and spectral (FTIR) analyses. SEM micrographs provided evidences of a smooth and homogeneous structure for nanostructured membranes without progesterone crystals on fiber surface. FTIR spectroscopy indicated miscibility and interaction between the ester of PLA and the ketone groups of the P4 in the nanofibers. X-ray analysis indicated that the size of PLA crystallites increased with progesterone content. Finally, by in vitro release experiments it was possible to observe that the progesterone releasing follows nearly first-order kinetics, probably due to the diffusion of hormone into PLA nanofibers.

Nonwoven mats of poly(lactic acid) (PLA), poly(ethylene oxide) (PEO), and poly(ε-caprolactone) (PCL) were prepared at a nano- and submicron scale by solution blow spinning (SBS) and electrospinning in order to compare crystalline structure and morphology developed by both processes during fiber formation. Polymer solutions were characterized by rheometry and tensiometry. Spun fibers were characterized by several analytical steps. SEM analyses showed that both solution blow spun and electrospun fibers had similar morphology. Absence of residual solvents and characteristic infrared bands in the solution blow spun fibers for PLA, PCL, and PEO was confirmed by FTIR studies. XRD diffraction patterns for solution blow spun and electrospun mats revealed some differences related to distinct mechanisms of fiber formation developed by each process. Significant differences in thermal behavior by DSC were observed between cast films of PLA, PCL, and PEO and their corresponding spun nanofibers. Furthermore, the average contact angles for spun PLA and PCL were higher than for electrospun mats, whereas it was slightly lower for PEO. When comparing electrospun and solution blow spun fibers, it was possible to verify that fiber morphology and physical properties depended both on the spinning technique and type of polymer.

The effect of UV-C irradiation of the TPS and PCL biocomposites with sisal bleached fibers was investigated. The biocomposite was UV-C irradiated at room temperature under air atmosphere. The structural and morphological changes produced when the films were exposed to UV irradiation for 142 h, were monitored using Scanning Electron Microscopy (SEM), Mechanical Tensile Tests, Differential Scanning Calorimetry (DSC), X-ray diffraction, Thermogravimetric analysis (TGA), and Fourier transform infra-red analysis (FTIR). Addition of 5–10% fibers in composites exhibited improved mechanical and thermal properties attributed to more efficient dispersibility of fiber in the matrix and good compatibility between fibers and the matrix polymer, however, after irradiated, the tensile properties decreased due to chain scission. The samples of irradiated PCL and TPS showed crystallinity increase, whereas the blend and composites showed a decrease in crystallinity. The DSC and X-ray diffraction studies suggested interaction between polymers in the blend via carboxyl groups in thermoplastic starch-PCL and hydroxyl groups in fibers.

Hydrogels with potential technological applications has been prepared using polyacrylamide (PAAm) and methylcellulose (MC) polymers by free radical polymerization reaction. The spectroscopic, morphological, swelling, and kinetic properties were investigated by solid state 13C VACP-MAS nuclear magnetic resonance (NMR), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), water uptake (WU) measurements, respectively. FTIR and NMR analysis confirmed the formation of semi-IPN structured hydrogel. Data from WU and SEM revealed that the addition of MC into the solution-forming hydrogel leads to increase in average pore size and hydrophilicity. By varying of AAm, MC, pH and ionic-strength of swelling medium, it was possible to obtain hydrogels with hydrophilic properties controlled and optimized. The water uptake mechanism is dependent of the AAm concentration, which can follow the Fickian diffusion and anomalous transport process. In this way, PAAm-MC hydrogels are promising materials for technological applications, such as agricultural field. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Cellulose nanowhiskers were prepared by sulfuric acid hydrolysis from coconut husk fibers which had previously been submitted to a delignification process. The effects of preparation conditions on the thermal and morphological behavior of the nanocrystals were investigated. Cellulose nanowhisker suspensions were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and X-ray diffraction. Results showed that it was possible to obtain ultrathin cellulose nanowhiskers with diameters as low as 5 nm and aspect ratio of up to 60. A possible correlation between preparation conditions and particle size was not observed. Higher residual lignin content was found to increase thermal stability indicating that by controlling reaction conditions one can tailor the thermal properties of the nanowhiskers.

The use of gold nanoparticles combined with other organic and inorganic materials for designing nanostructured films has demonstrated their versatility for various applications, including optoelectronic devices and chemical sensors. In this study, we reported the synthesis and characterization of gold nanoparticles stabilized with poly(allylamine hydrochloride) (Au@PAH NPs), as well as the capability of this material to form multilayer Layer-by-Layer (LbL) nanostructured films with metal tetrasulfonated phthalocyanines (MTsPc). Film growth was monitored by UV-Vis absorption spectroscopy, atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). Once LbL films have been applied as active layers in chemical sensors, Au@PAH/MTsPc and PAH/MTsPc LbL films were used in an electronic tongue system for milk analysis regarding fat content. The capacitance data were treated using Principal Component Analysis (PCA), revealing the role played by the gold nanoparticles on the LbL films electrical properties, enabling this kind of system to be used for analyzing complex matrices such as milk without any prior pretreatment.

Electrically conductive poly(vinylidene fluoride)(PVDF) – polyaniline blends of different composition were synthesized by chemical polymerization of aniline in a mixture of PVDF and dimethylformamide (DMF) and studied by electrical conductivity measurement, UV–Vis–NIR and FTIR spectroscopy. The samples were obtained as flexible films by pressing the powder at 180 °C for 5 min. The electrical conductivity showed a great dependence on the syntheses parameters. The higher value of the electrical conductivity was obtained for the oxidant/aniline molar ratio equal to 1 and p-toluenesulfonic acid–TSA/aniline ratio between 3 and 6. UV–Vis–NIR and FTIR spectra of the blend are similar to the doped PANI, indicating that the PANI is responsible for the high electrical conductivity of the blend. The electrical conductivity of blend proved to be stable as a function of temperature decreasing about one order at temperature of 100 °C. The route used to obtain the polymer blend showed to be a suitable alternative in order to obtain PVDF/PANI–TSA blends with high electrical conductivity.

A detailed structural characterization study is presented for composite Langmuir–Blodgett (LB) films containing varying compositions of the 16-mer polyaniline, processed with camphor sulfonic acid and m -cresol, and cadmium stearate. The mixed monolayer approach was selected as it has been proven to yield the most uniform LB films for conducting polymers. Because film uniformity was indeed excellent as verified by visual inspection and also using surface potential measurements, attempts were made to probe whether molecular level mixing occurred. However, X-ray diffraction (XRD) results have shown clearly that the cadmium stearate and the 16-mer molecules are phase separated. Diffractograms were obtained which are very close to that of pure cadmium stearate films, at least for low weight percentages of the 16-mer. When the 16-mer content was increased, the stacking order of the cadmium stearate domains was affected to a large extent, being no longer apparent for 75% of the 16-mer. The presence of cadmium stearate and 16-mer polyaniline in the composite LB film was also detected in a Fourier transform infrared spectroscopy (FTIR) analysis. The deposition of a layer-by-layer structure was confirmed through ellipsometry which also provided film thickness to be compared with the bilayer thickness from XRD data. The thickness was found to be dependent on the film composition, being mostly determined by the cadmium stearate domains up to 50 wt.% of the 16-mer in the composite.

The formation of Langmuir monolayers and Langmuir−Blodgett films is reported for the first time for a polyaniline oligomer, 16-mer, that was mixed with cadmium stearate. The processibility of this oligomeric material was greatly improved as compared to the parent polyaniline, which allowed one to use common solvents like chloroform as the spreading solvent. Analogously to composite polyaniline monolayers, the stability and the transferability are found to depend on the 16-mer content in the composite film, with poor stability and low transfer ratios above 60% of 16-mer. Deposited Langmuir−Blodgett films were found to be undoped (or only weakly doped) since they were obtained from monolayers spread onto aqueous subphases (pH = 6.0). Uniform Langmuir−Blodgett (LB) deposition was confirmed by optical microscopy and UV−vis spectra whose intensity increased linearly with the number of layers deposited and also with the 16-mer content. Fourier transform infrared (FTIR) results revealed that cadmium stearate was...

This paper reports on the development of bioactive edible films based on pectin as a dietary matrix and magnesium hydroxide (Mg(OH)2) nanoplates as a reinforcing filler. Nanocomposites of high-methoxyl (HM) and low-methoxyl (LM) pectins were prepared using the casting method at concentrations of Mg(OH)2 ranging from 0.5 to 5 wt %. Atomic force microscopy and FTIR spectroscopy were employed to characterize the nanocomposite structure. The tensile properties and thermal stability of the nanocomposites were also examined to ascertain the effect of Mg(OH)2 inclusion and degree of methoxylation. The results provided evidence that the Mg(OH)2 nanoplates were uniformly dispersed and interacted strongly with the film matrix. The mechanical and thermal properties were significantly improved in the nanocomposite films compared to the control. Mg(OH)2 nanoplates were more effective in improving properties of LM pectin. Preliminary migration studies using arugula leaves confirmed that pectin-Mg(OH)2 nanocomposites can release magnesium hydroxide by contact, demonstrating their potential for magnesium supplementation in bioactive packaging.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:01:52Z No. of bitstreams: 1 S0104-14282012000400002.pdf: 3348386 bytes, checksum: d2f1ce80a66d634acaba0b6c7b78fab3 (MD5) Made available in DSpace on 2013-08-22T19:01:52Z (GMT). No. of bitstreams: 1 S0104-14282012000400002.pdf: 3348386 bytes, checksum: d2f1ce80a66d634acaba0b6c7b78fab3 (MD5) Previous issue date: 2012-01-01 Made available in DSpace on 2013-09-30T20:02:16Z (GMT). No. of bitstreams: 2 S0104-14282012000400002.pdf: 3348386 bytes, checksum: d2f1ce80a66d634acaba0b6c7b78fab3 (MD5) S0104-14282012000400002.pdf.txt: 33656 bytes, checksum: 6c5077e4f30fec2154ce3067661894b5 (MD5) Previous issue date: 2012-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:29:43Z No. of bitstreams: 2 S0104-14282012000400002.pdf: 3348386 bytes, checksum: d2f1ce80a66d634acaba0b6c7b78fab3 (MD5) S0104-14282012000400002.pdf.txt: 33656 bytes, checksum: 6c5077e4f30fec2154ce3067661894b5 (MD5) Made available in DSpace on 2014-05-20T13:29:43Z (GMT). No. of bitstreams: 2 S0104-14282012000400002.pdf: 3348386 bytes, checksum: d2f1ce80a66d634acaba0b6c7b78fab3 (MD5) S0104-14282012000400002.pdf.txt: 33656 bytes, checksum: 6c5077e4f30fec2154ce3067661894b5 (MD5) Previous issue date: 2012-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Neste trabalho foi reportada a caracterização de hidrogéis constituídos por metilcelulose (MC) e poliacrilamida (PAAm) preparados pelo processo de reticulação cruzada. As propriedades espectroscópicas e morfológicas foram investigadas por espectroscopia no infravermelho com transformada de Fourier e microscopia eletrônica de varredura, respectivamente. O efeito da carga iônica, presença de sais, concentrações de monômero AAm e polissacarídeo MC na absorção de água e nas propriedades cinéticas dos hidrogéis foi detalhadamente investigado. Os resultados indicaram que o decréscimo da concentração de MC ou aumento da concentração de AAm, carga iônica do contra-íon do sal de cloreto e a presença de fertilizante no meio externo de intumescimento provocaram diminuição significativa na absorção de água dos hidrogéis. O mecanismo de absorção de água dos hidrogéis de PAAm-MC em água seguiu o modelo de difusão Fickiana; já o mecanismo dos hidrogéis intumescidos em sais (cloreto ou fertilizante) seguiu o modelo de transporte anômalo. Pela alta e rápida absorção de água, as matrizes porosas e tridimensionais compostas por PAAm e MC podem em potencial ser aplicadas na agricultura como veículos carreadores. This work reported the characterization of hydrogels constituted by methylcellulose (MC) entrapped in polyacrylamide (PAAm) network prepared by cross-linking polymerization (gelling process). Spectroscopic and morphologic properties were investigated using Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. Effects of AAm, MC contents, ionic charge of salt counter-ions (NaCl, KCl, NH4Cl, CaCl2, MnCl2, MgCl2, and AlCl3), and fertilizers [(NH4)2SO4 and KH2PO4] on kinetic and hydrophilic (swelling degree) properties were investigated in detail. By decreasing the MC content or by increasing acrylamide content, there was a pronounced decrease in water uptake by the hydrogels. The increase in counter-ion X-Cl salt and the presence of fertilizer on the external swelling medium also provoked a decrease in water uptake. The water uptake mechanism of PAAm-MC hydrogels swollen in water followed the Fickian diffusion, while the mechanisms of hydrogels swollen in salt or fertilizer aqueous media followed the anomalous transport process. With their fast and high water absorption, the porous, three-dimensional matrices containing PAAm and MC are promising for agriculture as carrier vehicles. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) Instrumentação Laboratório Nacional de Nanotecnologia para o Agronegócio UFSCar Departamento de Química UNESP Instituto de Química UNESP Instituto de Química

The chemical synthesis of a new soluble polyaniline derivative, poly( o -phenetidine), was carried out with monomer excess and the polymer obtained was characterized by elemental analysis, FTIR, UV-vis spectroscopy, gel permeation chromatography, X-ray diffraction and cyclic voltammetry. The poly( o -phenetidine) has chemical and structural properties which are consistent with a pure polymer in the emeraldine oxidation state. Poly( o -phenetidine) Langmuir monolayers were spread from chloroform or dichloromethane solutions on an aqueous solution whose pH was varied from 6 to 2. Because kinetic effects on monolayer compression are extremely important for monolayers from preformed polymers, the influence of the various experimental parameters on the monolayer characteristics was investigated. It is shown that high transfer ratios are obtained in the LB deposition process when Langmuir monolayers are fabricated from very dilute dichloromethane solutions, spread on a low pH subphase, and compressed at a barrier speed of 30 mm min −1 . The monolayer is then transferred onto a solid substrate by vertical dipping. UV—visible spectroscopy and cyclic voltammetry of the deposited LB films reveal essentially the same behavior as cast poly( o -phenetidine) films.

The need for biodegradable polymers for packaging has fostered the development of novel, biodegradable polymeric materials from natural sources, as an alternative to reduce amount of waste and environmental impacts. The present investigation involves the synthesis of chitosan nanoparticles–carboxymethylcellulose films, in view of their increasing areas of application in packaging industry. The entire process consists of 2-steps including chitosan nanoparticles preparation and their incorporation in carboxymethylcellulose films. Uniform and stable particles were obtained with 3 different chitosan concentrations. The morphology of chitosan nanoparticles was tested by transmission electron microscopy, revealing the nanoparticles size in the range of 80 to 110 nm. The developed film chitosan nanoparticles–carboxymethylcellulose films were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis, solubility tests, and mechanical analysis. Improvement of thermal and mechanical properties were observed in films containing nanoparticles, with the best results occurring upon addition of nanoparticles with 110 nm size in carboxymethylcellulose films. Practical Application: Carboxymethylcellulose films containing chitosan nanoparticles synthesized and characterized in this article could be a potential material for food and beverage packaging applications products due to the increase mechanical properties and high stability. The potential application of the nanocomposites prepared would be in packaging industry to extend the shelf life of products.

In this work the preparation of chitosan nanoparticle was investigated using methacrylic acid in different conditions and studied by particle size analyzer, zeta-potential, Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). The particle size was dependent on the chitosan concentration used during the preparation method. Nanoparticles with sizes as small as 60 nm were achieved, that can be extremely important for several applications. The nanoparticles solution was also pH-sensitive, due to swelling and aggregation of the nanoparticles. The nanoparticles obtained presented a very homogeneous morphology showing a quite uniform particles size distribution and a rather spherical shape.