We report the preparation of flexible polystyrene/polypyrrole (PS/PPy) mats and their successful use as a resistive humidity sensor. These composite membranes were prepared by first obtaining PS ...films through the electrospinning technique, and then incorporating PPy chains by an in situ chemical polymerization of the pyrrole monomer. The PS fibers were homogeneously distributed, with diameters that obeyed a normal distribution with an average value of (1.04 ± 0.12) μm. The deposition of conducting PPy chains on the surface of the PS fibers was confirmed after characterizing the PS/PPy mats by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), contact angle measurements, and electrochemical impedance spectroscopy (EIS). When used as humidity sensors, the PS/PPy mats exhibited a sensor response of 128.6%, with fast response ((54.9 ± 3.5)s) and recovery times ((76.8 ± 11.1)s), and stable response under different humidity conditions over several days. These performance characteristics compare favorably to those of previous resistive humidity sensors discussed in the literature.
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•We deposited polypyrrole (PPy) chains on electrospun polystyrene (PS) films by in situ polymerization.•We examined the use of these hydrophilic PS/PPy films as resistive humidity sensors.•The hybrid PS/PPy films exhibit good sensing response towards the presence of water vapor and fast response times.•The hybrid PS/PPy films appear as promising active materials for the development of humidity sensors.
After preparing composite PSGO films by coating electrospun polystyrene (PS) fibers with graphene oxide (GO), we examined their use as dye adsorbents for water remediation. The GO, which was ...synthesized via a modified Hummers' method, was adsorbed on the surface of the PS fibers. Through X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TGA) analyses, we characterized the structure and morphology of the composite films, confirming that the GO was successfully incorporated onto the PS fibers. SEM images revealed that the PS fibers exhibited a smooth surface and that the GO was uniformly deposited on them. TGA analysis indicated that the PSGO is composed of ∼13 wt% GO and ∼87 wt% PS, and that both components exhibited similar thermogravimetric behavior. We examined the removal of the methylene blue (MB) dye from aqueous solutions as a model system to assess the adsorptive properties of the PSGO films. The composite films had a removal capacity that was approximately 2.3 times greater than that of pure PS membranes. For all MB concentrations investigated, the removal of the dye, which was very fast in the first 30 min, the equilibrium value of the adsorption capacity (qe = 114 mg g−1) was reached after 120 min. The kinetics of the adsorption process was best described by the pseudo-second-order (PSO) model, which predicted an adsorption capacity (qt) of 116.69 mg g−1.
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•Fabrication and use of electrospun polystyrene fiber covered with graphene oxide.•GO-coated polystyrene is a promising adsorbent of the Methylene Blue dye.•Outstanding adsorptive capacity in comparison to other reported adsorbents.
We report the preparation of polyacrylonitrile/polypyrrole/polyaniline (PAN/PPy/PANI) mats, a new type of composite membrane obtained through an in situ chemical polymerization of pyrrole and aniline ...on an electrospun polymeric matrix of polyacrylonitrile, and their use for the capture and removal of Remazol Black B (RBB) dye molecules dissolved in an aqueous media. We characterized these membranes through scanning electron microscopy (SEM), Fourier Transform Infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), thermogravimetric analysis (TGA), and contact angle measurements. We observed that the coating of electrospun PAN fibers was uniform, with the resulting membrane exhibiting a hydrophilic character. When exposed to RBB aqueous solutions at room temperature, the PAN/PPy/PANI mats presented the highest adsorption capacity (247.7 mg g−1) at pH 2. While the kinetics and adsorption isotherm data were best described by pseudo-second-order (PSO) and Langmuir models, respectively, the RBB adsorption was favored by an increase in the temperature. After subjecting the RBB-loaded membrane to different elution procedures, we were able to achieve full desorption in just 10 min. The thermal and environmental stability of the composite membranes allowed us to use them in at least 6 consecutive adsorption/desorption cycles without noticeable loss of their properties. These results suggest that PAN/PPy/PANI membranes are promising adsorbent materials for use in water remediation protocols.
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•We deposited polypyrrole and polyaniline on electrospun polyacrylonitrile films.•The PAN/PPy/PANI mats exhibited excellent capacity for adsorbing Remazol Black B.•The dye captured by the membranes can be completely desorbed in just 5 min.•These composite mats can be used in several adsorption/desorption cycles.
Colon cancer is one of the world’s most deadly diseases. Because of its internal location, it is necessary to obtain faster and more efficient diagnostic tools for this organ site. In this context, ...we studied the development of new luminescent nanoprobes (LNPs) as an alternative diagnostic apparatus for detecting this disease. The nanoparticles examined herein are lanthanide-doped sodium yttrium fluoride (NaYF
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:Ln) and have shown to be promising as investigative devices. However, significant problems with the use of LNPs are the lack of biocompatibility and the targeting of the system to tumor regions. One of the strategies to bypass these problems is to increase of the particle lipophilicity modifying their surfaces with organic compounds that present high similarity to the biological system. In this work, we synthesized six new materials for use in bioimaging techniques obtained from the combination of nanoparticles of NaYF
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:5%Eu with organic aromatic compounds covalently bonded. The materials were characterized structurally and morphologically using XRD and TEM, techniques, which showed the identification of the crystallographic phase β-NaYF
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:5%Eu and its nanometric size (particles smaller than 50 nm). The conjugation process was confirmed by FT-IR spectra analysis and from the TGA profile. Excitation and emission spectra allowed the evaluation of the optical properties of the synthesized compounds. The interaction and cellular uptake was confirmed when HT-29 colon cancer cells were exposed to LNPs, indicating that the developed system has promising applications in bioimaging procedures.
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Gastrointestinal parasites are one of the biggest health problems faced in sheep, mainly due to their pathogenicity and resistance to drugs used to control these parasites. Thus, the following study ...aimed to assess the anthelmintic efficacy of Melaleuca alternifolia against Haemonchus contortus in gerbils (Meriones unguiculatus) experimentally infected. Three treatments were tested: M. alternifolia essential oil, popularly known as tea tree oil (TTO), a solid lipid nanocarrier made with essential oil of Melaleuca (nanoTTO), and terpinen-4-ol (terp-4-ol). In vivo studies were performed by determining the mean worm burden of H. contortus in gerbils TTO (0.75 mL/kg); nanoTTO (0.5 mL/kg) and terp-4-ol (0.5 mL l/kg) were able to reduce 46.36%; 48.64%, and 43.18% worm burden, respectively. H. contortus increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, as demonstrated by liver injury. It was found that the TTO, nanoTTO, and terp-4-ol were not toxic to liver and kidneys since hepatic and renal functions were not affected. Moreover, terp-4-ol was able to prevent increased levels of seric AST and ALT in infected animals, indicating a hepatoprotective effect. Thus, our results indicate that TTO, nanoTTO, and terp-4-ol are safe and efficient against H. contortus infection in gerbils, and possibly the terp-4-ol may be considered the compound present in the Melaleuca alternifolia responsible for parasitic action against H. contortus.
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•The treatments used were effective on reducing infection by H. contortus in gerbils.•The nanocarriers used with essential oil of M. alternifolia (nanoTTO) showed highest efficiency.•Nanotechnology can increase efficacy and bioavailability of therapeutic substances.•Terpinen-4-ol may protect against liver damage caused by infectious agents.
The aim of this study was to evaluate the nitric oxide (NO) levels, and oxidative and antioxidant markers of lambs experimentally and naturally infected by Haemonchus contortus, and its relation to ...lesions in the abomasum. For experimental study, a total of 14 healthy lambs were divided into two groups with seven animals each. Group A represented the uninfected animals (control), and Group B was formed by infected animals with 15,000 larvae of H. contortus. Blood was collected on days 15, 45, and 75 post-infection (PI) to obtain serum for biochemical analysis: lactate dehydrogenase (LDH), nitrite/nitrate (NOx), advanced oxidation protein products (AOPP), and ferric reducing ability of plasma (FRAP). Parasitological stool examination (eggs per gram of feces – EPG) was performed on days 15, 45, and 75 PI to verify the evolution of the infection. On day 15 PI EPG was negative, but on days 45 and 75 PI the EPG was positive for animals from Group B. In the three periods evaluated it was observed an increase of LDH levels in serum of lambs infected with gastrointestinal nematodes, but on the other hand NOx levels were reduced on the same periods in infected animals. The AOPP and FRAP levels did not differ between groups on days 15 and 45 PI, but increased significantly on day 75 PI in infected lambs. The same variables were studied in 10 lambs naturally infected with helminths, where more than 97% corresponded to H. contortus (hematocrit and EPG values were 18.8±2.5% and 7120±2940, respectively). Similar to the experimental study, the levels of NOx reduced, and the levels of LDH, FRAP, and AOPP increased in serum of this animal associated inflammatory infiltrate in the mucosa of the abomasum. Therefore, during the infection by H. contortus it was observed alterations in oxidative markers, indicators of cell lesion confirmed by histological examination of the abomasum, and consequently there were changes in antioxidant levels, with the purpose of cell protection. We also conclude that helminth infection interferes with the nitric oxide metabolism.
