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This study aimed to develop a new bioactive wound dressing based on electrospun poly (L-lactide-co-D, L-lactide) (PLDLLA) nanofibers containing Lawsonia Inermis (LI) for burn wounds. The SEM results showed that loading LI increased the average diameter of PLDLLA nanofibers to 528 nm with smooth and beadless morphology. The analysis of LI release from PLDLLA nanofibers and film samples was measured by UV-vis spectrophotometry, and the obtained results revealed that LI molecules could diffuse from the nanofibrous sample with a higher rate than film ones during 48 h. In this regard, the PLDLLA nanofibrous sample as a drug carrier has advantages compared to the film. Moreover, the antibacterial results confirmed the positive influence of LI related to the bacteria which in turn the growth inhibition zones were increased from 6 to 22 mm for

Used lubricating oil (ULO) is a heavy mixture of various hydrocarbons and needs to be treated before discharging. Considering ULO nature, it is more favorable to recover lighter hydrocarbon cuts fr...

Kiwi extract (KE) including different components such as quercetin, vitamins C and E, and actinides has been known as a debridement agent for burn wounds. In this study, electrospun poly(ɛ-caprolactone)/cellulose acetate blend nanofibers incorporating KE (PCL/CA/KE) were prepared and their performance was evaluated for healing acceleration of burn wounds. The physicochemical characterization of PCL/CA/KE nanofibers showed an average diameter of ∼420 nm, porosity of 70%, water contact angle of 61°, and water uptake of ∼220%. Moreover, the continuous release trend of KE from PCL/CA blend nanofibers happened during 24 h and the release mechanism was governed by the Fickian diffusion. Besides the cytocompatibility of PCL/CA/KE nanofibers, their in vivo experiments revealed that the bioactive wound dressing based on the sample has higher wound closure compared to KE after 21 days. Histopathology of wounds dressed by PCL/CA/KE nanofibers indicated epidermal formation along with a fully extended layer. Eventually, the obtained results confirmed that the PCL/CA/KE nanofibrous sample was a promising wound dressing for burn wound healing.

Background: Nanomaterials have a significant role in improving the performance of electrochemical sensing systems. Unique physical and chemical properties have extended the application of nanomaterials in the fields of engineering, materials and biomedical science. In the last few years, these materials with unique properties have been preferred in the design of experimental approaches for the analysis of metal ions, proteins, biomarkers and pharmaceutical compounds. This paper reports preparation, characterization of two different nanomaterials and their electrochemical application on doublestranded calf-thymus DNA signals. Methods: The multi-walled carbon nanotubes were functionalized with amine groups (MWCNTs-NH2) by employing the dielectric barrier discharge plasma treatment and then applied as MWCNTs- NH2/glassy carbon electrode. Moreover, the synthesized mesoporous silica MCM-41 was chemically amine functionalized and used as MCM-41-NH2/carbon paste electrode. For biosensor preparation, a thin layer of calf thymus double stranded deoxyribonucleic acid (ct-dsDNA) was immobilized over the modified electrodes. Results: The influence of dsDNA immobilized substrate was investigated based on the electrochemical signals. While dsDNA/MCM-41-NH2/carbon paste biosensor showed a selective effect for guanine signals, the dsDNA/MWCNTs-NH2/glassy carbon biosensor presented electrocatalytic effect for dsDNA signals. Both dsDNA modified electrodes were employed to explore the interaction between the dsDNA and the anticancer drug etoposide (ETP) in aqueous solution through voltammetric techniques. By increasing the interaction time with ETP, the adenine peak current was quenched in the presence of MWCNTs-NH2 based glassy carbon electrode. Whereas, in the presence of MCM-41-NH2 based CP electrode, selective interaction with guanine occurred and oxidation peak intensity was diminished. Conclusion: The selective effect of MCM-41-NH2 can be used when the studied substances give a signal with the same potential of adenine.

The electron transfer of redox-active sites of immobilised haemoglobin (Hb) has been studied by voltammetric experiments. The electrode surface was modified by nanoparticles (NPs) to make a suitable substrate for electric wiring of protein molecules and efficient electron transferring. Hence, the Hb/zinc oxide NPs/platinum electrode was prepared by chronoamperometric deposition of the NPs and immobilisation of protein molecules. The electrochemical behaviour of the prepared biosensor was quasi-reversible and showed a pair of redox peaks with a formal potential (E 0′) of 214 mV. Additionally, the electron transfer rate constant (ks ) of immobilised Hb was about 0.621 s−1. Biocatalytic reduction of hydrogen peroxide was also examined on the prepared biosensor. Result indicated to good sensitivity, wide linear range and low detection limit of 6 μM.

The objective of this work was to prepare electrospun cellulose acetate (CA) nanofibers containing betamethasone sodium phosphate (BSP). Two different morphologies including random and aligned orientations were rationally designed to improve the performance of samples in in vitro experiments. By comparing the CA nanofibrous samples with randomly and aligned-oriented morphologies, the scanning electron microscopy images showed that the neat aligned-oriented nanofibers with an average diameter of 180±15 nm could be obtained using a high-speed rotating collector. Subsequently, the tensile test confirmed that the aligned CA nanofibers had higher mechanical properties than that of the randomly oriented ones. Moreover, the BSP release profile obtained by UV-vis spectrophotometry depicted that the aligned samples had an initial burst release of BSP followed by a slow penetration of the drug with a gentle slope during 72 h. Furthermore, the ultimate amounts of BSP released from the random and aligned CA nanofibers into the phosphate buffer solution were 63% and 53%, respectively. Finally, human adipose-derived mesenchymal stem cells were seeded on both aligned and random electrospun CA nanofibrous samples containing BSP. The thiazolyl blue and hematoxylin and eosin staining results showed that the BSP-loaded nanofibers with the aligned morphology provided the most suitable environment for the cells’ growth, viability, and proliferation.

Europium-doped yttrium oxide nanoparticles (Y2O3:Eu NPs) modified by captopril were prepared in aqueous solution. In this study, we report the effect of pyridoxine hydrochloride on the photoluminescence intensity of Y2O3:Eu NPs in pH 7.2 buffer solution. By increasing the pyridoxine concentration, the luminescence intensity of Y2O3:Eu NPs is quenched. The results show that this method demonstrates high sensitivity for pyridoxine determination. A linear relationship is observed between 0.0 and 62.0 μM with a correlation coefficient of 0.995 and a detection limit of 0.023 μM. Copyright © 2014 John Wiley & Sons, Ltd.

In the recent decade, there has been a growing interest in using electrospun polymeric scaffolds for sustained release of drugs. In this work, fibrous scaffolds of polylactic acid/polyethylene glycol (PLA/PEG) were prepared and characterized through scanning electron microscopy, for subsequent utilization as the drug delivery system for cefixime (CF). In this regard, the response surface experimental design (RSM) was successfully used for finding optimized electrospinning condition such as total solution concentration (C_tot), PEG content (%PEG), and applied voltage (V) on the morphology of electrospun PLA/PEG fibrous mats. While increasing the applied voltage and reducing both solution concentration and %PEG resulted in thinner fibers, C_tot was the influential factor on the fiber defects and continuity. Finally, PLA/PEG/CF fine fibers were produced under optimized electrospinning conditions and the controlled drug release profile was obtained in the presence of graphene oxide (GO). GO-CF intermolecular interactions, revealed by attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR) analysis, authorized the drug release mechanism and resulted in near-Fickian diffusion of cefixime from the PLA/PEG/CF/GO fibrous mats.

A sensitive electrochemical sensor is formed by a carbon nanoparticles (CNPs)/glassy carbon electrode for the determination of antidepressant drug fluoxetine in pharmaceutical formulation. The dependence of fluoxetine electro-oxidation currents and potentials on pH concentration and the potential scan rate was studied. Scanning electron microscopy was used for characterisation of the CNPs. The porous layer of the CNPs improved the electroactive surface area and led to a significant increasing in the peak currents, based on the diffusion within a nanoporous film. The best electrochemical response was obtained from differential pulse voltammograms in the buffer solution (pH 9.0). Linear calibration graphs were obtained in 1–25 µM with %RSD values from 0.3 to 5.7 and the detection limit of 0.4 µM (S/N = 3). The CNPs modified electrode was successfully applied for fluoxetine determination in capsules and the results showed sufficient precision and achieved a mean recovery accuracy of 99.06%.

Amlodipine besylate and atorvastatin calcium have been determined by the simultaneous voltammetric method at a multi-walled carbon nanotubes:graphite (MWCNTs:G) paste electrode. In comparison with a glassy carbon electrode, the prepared electrode showed an increase in the peak current because of the high electroactive surface area and excellent electronic conductivity of MWCNTs. The dependence of currents and potentials on pH were investigated for these components at the surface of the MWCNTs:G paste electrode. Differential pulse voltammetry was applied as a sensitive technique for simultaneous determination of the drugs in commercial tablets. By anodic differential pulse voltammetry, the calibration plot was linear in the range of 2.5-100 μg/ml with standard deviation between 2.7-7.1 and 1.8-8.3% for amlodipine and atorvastatin, respectively. The detection limit was 1 μg/ml at the prepared electrode in the buffered solution pH 6.

We report on a novel luminescent method for the detection of folic acid (FA), a member of the vitamin B family. Y2O3 nanoparticles were doped with europium(III) ions and surface-modified with captopril. Their fluorescence is quenched by FA, and intensity is a function of folic acid concentration in the 0.1 – 40 μM concentration range. The detection limit is 83 nM of FA at pH 7 and room temperature.

Polyaniline (PANI)/Ag nanocomposites were successfully synthesized via in situ chemical oxidative and enzymatic polymerization of aniline based on 2-aminothiophenol (2-ATP)-capped Ag nanoparticles. The approach to the fabrication included three steps: (i) the preparation of silver nanoparticles; (ii) the formation of an ATP monolayer on the silver particle surface, which serves as a binder; and (iii) the polymerization of aniline monomers joined to ATP by using ammonium persulfate in the chemical method, and horseradish peroxidase in the presence of sulfonated polystyrene as a polyanionic template and H2O2 as an oxidized agent in the enzymatic method. Comparison of the results revealed that the enzymatic method is more suitable because not only the size of the nanocomposites was smaller but also their thermal stability was more improved with the enzymatic method than with chemical one.

Direct electrochemical response of cytochrome c (cyt c) on the modified electrode was studied by cyclic voltammetry. The results indicated that cyt c could be adsorbed on the surface of the electrodeposited cobalt oxyhydroxide nanoparticles (CoOx NPs) modified electrode. A couple of well-defined redox peaks can be observed in a phosphate buffer solution (pH 7.0), whose formal potential, E°′ (defined as the average of reductive and oxidative peaks), was −86.5 mV with respect to the reference electrode equal to 110.5 mV against normal hydrogen electrode. Cyt c adsorbed on the surface of CoOx NPs shows a remarkable electrocatalytic activity for the reduction of oxygen. Based on these, a third-generation biosensor could be developed to detect the concentration of oxygen in aqueous solution.

The in situ enzymatic polymerization of aniline onto multi-walled carbon nanotubes (MWCNT) and carboxylated MWCNT (COOH-MWCNT) is reported. Nanostructured composites were prepared by this method. Polymerization was catalyzed with the enzyme horseradish peroxidase at room temperature in aqueous medium of pH 4. Hydrogen peroxide was used in low concentration as the oxidant. The nanocomposites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The TEM studies showed tubular morphology with uniformly distributed MWCNT in the nanocomposites. The SEM and TEM investigations revealed wrapping of the MWCNT with polyaniline (PANI) chains. TGA demonstrated that the PANI component is thermally more stable in PANI/COOH-MWCNT compared to the PANI/MWCNT composites. The synthesized nanocomposites showed higher conductivity than pure PANI, which may be due to the strong interaction between the PANI chains and the MWCNT.

A fiber coated by polyaniline (PANI) was obtained through electrochemical deposition and applied for solid-phase microextraction (SPME). The same method was applied for the preparation of an SPME fiber coated by a PANI/multiwalled carbon nanotubes (PANI/MWCNTs) composite. The prepared fibers were employed for extraction of methylenedioxymethamphetamine (MDMA) hydrochloride from aqueous and chloroform samples. The resulting substances were analyzed by gas chromatography-mass spectrometry. The developed method proved to be simple with high reproducibility. The amount of extracted MDMA hydrochloride from aqueous solution and MDMA from chloroform solution by the PANI/MWCNTs fiber was about 3.5-fold and 2-fold that of the one without CNTs. It could be suggested that the composite material with CNTs has both an augmented surface area and an elevated adsorptive capacity which lead to the increased extractive capacity for MDMA.

We report on the application of nanocrystals (NCs) of the type Y2O3: Eu,Zn as a probe for the fluorescent detection of biotin in aqueous solution. The NCs were dispersed in water in the presence of various surface modifiers including mercaptoethanol (ME), monoethanolamine and ethylene glycol. Both the absorbance of surfactant and the stability of the suspensions were investigated in order to optimize the experimental conditions. ME is found to be the most suitable surfactant for stabilization of the suspended NCs. Their photoluminescence intensity is found to be quenched by biotin. The Stern-Volmer constant for the quenching process is 7.6 × 103 M−1. This NC probe can be applied to the detection of biotin in the 1–60 μM concentration range with detection limit of 1.89 μM. The possible mechanisms of quenching also are discussed.

In this work, various nano-sized samples of Y 2 O 3, Y 2 O 3 :Eu and Y 2 O 3 :Eu , Sr were prepared by urea solution combustion method. Then the resultant nanopowders were investigated by means of X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR) and photo-luminescence emission spectra. Furthermore, the CIE color coordinate of samples were calculated from photoluminescence emission spectra. Results showed that by doping of strontium, the photoluminescence intensity and chromaticity of Y 2 O 3: Eu phosphor was enhanced while crystallite size was decreased.

Ferritin was immobilized on a glassy carbon electrode with electrodeposited cobalt oxide nanoparticles, and its direct electron transfer behavior was studied. It exhibits a pair of redox peaks due to direct electron transfer between ferritin and the nanoparticles. Electrochemical parameters including the formal potential (E0′), the charge transfer coefficient (α), and the apparent heterogeneous electron transfer rate constant (ks) were determined. The sensor displays excellent biocatalytic activity in terms of reduction of hydrogen peroxide, and this was applied to electrochemical sensing of hydrogen peroxide.

Erbium oxide nanoparticles (Er2O3 NP) were synthesized with an efficient method in the presence and absence of sodium dodecylsulfate (SDS) as surfactant. The effect of SDS on the morphology of the synthesized Er2O3 NP is described. The NP were studied through scanning electron microscopy and X-ray diffractometry. Then, polyaniline and a hybrid material of polyaniline/Er2O3 NP were deposited directly on a stainless steel wire by the potentiostatic process. The electrochemical data and scanning electron microscopic studies of polyaniline and its nanocomposite on the stainless steel wire demonstrate the influence of the synthesized Er2O3 NP on the electrodeposition of polyaniline. The presence of NP in the electrolyte solution during electrodeposition of polyaniline creates a nanocomposite with a more porous structure than pure polyaniline.

We describe a modification of glassy carbon (GC) electrode surface with electrodeposited cobalt oxide nanoparticles (CoOx NPs), and then, this electrode is used to immobilization of Cytochrome c (Cyt c). The morphology of electrodeposited CoOx NPs was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Electrochemical redox property investigation of immobilized protein (Cyt c) molecules was accomplished by cyclic voltammetry (CV) technique. Cyt c/CoOx NPs/GC electrode exhibits electron transfer between the protein prosthetic groups and electrodeposited nanoparticles on the electrode surface and displayed a couple of stable redox peaks with a formal potential (E°′) of −89.5 mV (107.5 mV vs. NHE) with respect to reference electrode in 0.05 M phosphate buffer solution (pH 7.0). The experimental results demonstrated that Cyt c/CoOx NPs/GC biosensor exhibited electrocatalytic activity toward the reduction of hydrogen peroxide and application to hydrogen peroxide determination was exemplified.

The oxidation of acetaminophen was studied at a glassy carbon electrode modified with multi-walled carbon nanotubes and a graphite paste. Cyclic voltammety, differential pulse voltammetry and square wave voltammetry at various pH values, scan rates, and the effect of the ratio of nanotubes to graphite were investigated in order to optimize the parameters for the determination of acetaminophen. Square wave voltammetry is the most appropriate technique in giving a characteristic peak at 0.52 V at pH 5. The porous nanostructure of the electrode improves the surface area which results in an increase in the peak current. The voltammetric response is linear in the range between 75 and 2000 ng.mL−1, with standard deviations between 0.25 and 7.8%, and a limit of detection of 25 ng.mL−1. The method has been successfully applied to the analysis of acetaminophen in tablets and biological fluids.

Inorganic nanoparticles combined with conducting polymers provide interesting physical properties. This research describes the aniline polymerization taking place on the nanoparticles surface by catalytic oxidative polymerization with metalloporphyrin and metallophthalocyanine. In this way, the core-shell structure of the polyaniline/ TiO2 nanocomposites was obtained. The comparison of results demonstrates that porphyrin is a better catalyst than phthalocyanine for synthesis of nanocomposite. The morphology and composition of the nanocomposites were characterized by techniques such as SEM and FT-IR spectroscopy. TGA analysis showed that the nanocomposites, synthesized with iron(III) tetrasulfonated tetraphenyl porphyrin and iron(II) tetrasulfonated phthalocyanines, contained 10% and 5% conducting polyaniline (by mass), respectively. Eventually, the voltammograms revealed that these nanocomposites were electroactive and there was a linear relationship between the anodic and cathodic peak current values and scan rates.

Peroxidase-catalyzed template-guided polymerization of aniline in the presence of γ- alumina nanosheet (NS) particles have been carried out in aqueous media and γ-Al2O3/PANI nanocomposite was obtained. The polymerization of aniline occurred in aqueous solution in the presence of SPS (sulfonated polystyrene) as a template and SDS (sodium dodecyl sulfate) as a surfactant. Both obtained nanocomposites were comparable by SEM images. It was demonstrated that the γ-Al2O3 NS/PANI-SPS nanocomposite has higher conductivity and the γ-Al2O3 NS/PANI-SDS nanocomposite has higher void areas. The higher conductivity of γ-Al2O3 NS/PANI-SPS nanocomposite is attributed to the higher coated areas of γ-Al2O3 NS during polymerization in comparison with γ-Al2O3 NS/PANI-SDS which are not coated efficiently as the former. The FT-IR studies showed that the γ-Al2O3 NS/PANI nanocomposite was formed by interaction of the polyaniline (PANI) and γ-Al2O3 NS. FTIR also showed that the amount of PANI in γ-Al2O3 NS/PANI-SPS is more than in γ-Al2O3 NS/PANI-SDS. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

The voltammetric behavior of cinnamic acid (CA) and 3, 4-dihydroxy benzoic acid (BA) at an glassy carbon disc electrode has been investigated. The obtained cyclic voltammograms showed that their oxidation peaks were over- lapped and it was difficult to determine them individually from a mixture without separation. To overcome this limitation, partial least squares (PLS) modeling, as a powerful multivariate statistical tool, was proposed for the resolution of the overlapped voltammetric signals from mixtures of CA and BA. With the help of the orthogonal signal correction (OSC), the unrelated information was removed and the results were confirmed. In this procedure, the genetic algorithm (GA) was used for the potentials selection for PLS. In addition, OSC-GA-PLS for the first time was used and the results of this method were better than those of the other methods. The proposed method was suitable for the determination of CA and BA in mixtures.