Synthesis,structural and optical properties of tin oxide nanoparticles and its CMC/PEG–PVA nanocomposite films

Polyethylene glycol–polyvinyl alcohol (PEG–PVA) blend is a multifunctional material and controlling its properties is important for various medical and industrial uses. In this paper, we report the influence of carboxymethyl cellulose (CMC) and doping with tin oxide (SnO₂) nanoparticles (NPs) on the structural and optical properties of PEG–PVA. The prepared samples were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and UV–Vis-NIR spectroscopies. SnO₂ NPs of rutile structure, average crystallite size of ～30.2 nm and optical band gap (E_g) of 3.68 eV were prepared by a simple sol–gel process. CMC addition enhances the crystallinity of PEG–PVA that then gradually reduced by increasing SnO₂ doping ratio. The optical transmittance of PEG–PVA increased from 77 to 90% after mixing with CMC and then decreased to 64% with increasing SnO₂ content to 1.5%. Also, the E_g of PEG–PVA increased from 5.20 to 5.28 eV and then decreased to 4.88 eV due to CMC addition and SnO₂ incorporation, respectively. The refractive index, the dispersion parameters and the optical conductivity of PEG–PVA, CMC/PEG–PVA and of its nanocomposite films are discussed. The correlation between the structural modifications and the resultant optical properties are reported.     

Definitive Screening Design and Artificial Neural Network for Modeling a Rapid Biodegradation of Date Palm Fronds by a New Trichoderma sp. PWN6 into Citric Acid

Generally, the bioconversion of lignocellulolytics into a new biomolecule is carried out through two or more steps. The current study used one-step bioprocessing of date palm fronds (DPF) into citric acid as a natural product, using a pioneer strain of Trichoderma harzianum (PWN6) that has been selected from six tested isolates based on the highest organic acid (OA) productivity (195.41 µmol/g), with the lowest amount of the released glucose. Trichoderma sp. PWN6 was morphologically and molecularly identified, and the GenBank accession number was MW78912.1. Both definitive screening design (DSD) and artificial neural network (ANN) were applied, for the first time, for modeling the bioconversion process of DPF. Although both models are capable of making accurate predictions, the ANN model outperforms the DSD model in terms of OA production, as ANN is characterized by a higher value of R² (0.963) and validation R² (0.967), and lower values of the RMSE (13.44), MDA (11.06), and SSE (9749.5). Citric acid was the only identified OA as was confirmed by GC-MS and UPLC, with a total of 1.5%. In conclusion, DPF together with T. harzianum PWN6 is considered an excellent new combination for citric acid biosynthesis, after modeling with artificial intelligence procedure.     

Assessment of Conventional Solvent Extraction vs. Supercritical Fluid Extraction of Khella (Ammi visnaga L.) Furanochromones and Their Cytotoxicity

Background: Khella (Ammi visnaga Lam.) fruits (Apiaceae) are rich in furanochromones, mainly khellin and visnagin, and are thus incorporated in several pharmaceutical products used mainly for treatment of renal stones. Methods: The objective of this study was to compare the yield of khellin and visnagin obtained using different conventional solvents and supercritical fluid extraction (SCFE) with carbon dioxide (containing 5% methanol as co-solvent). Water, acetone and ethanol (30% and 95%) were selected as conventional solvents. Results: Highest extract yield was obtained from 30% ethanol (15.44%), while SCFE gave the lowest yield (4.50%). However, the percentage of furanochromones were highest in SCFE (30.1%), and lowest in boiling water extract (5.95%). HPLC analysis of conventional solvent extracts showed other coumarins that did not appear in supercritical fluid extraction chromatogram due to non-selectivity of solvent extraction. Ammi visnaga extracts as well as standard khellin and visnagin were tested for their cytotoxic activity using sulforhodamine B assay on breast cancer (MCF-7) and hepatocellular carcinoma (Hep G2) cell lines. Results revealed a strong cytotoxic activity (IC₅₀ < 20 µg/mL) for the SCFE and standard compounds (khellin and visnagin) (IC₅₀ ranging between 12.54 ± 0.57 and 17.53 ± 1.03 µg/mL). However, ethanol and acetone extracts had moderate cytotoxic activity (IC₅₀ 20–90 µg/mL) and aqueous extract had a weak activity (IC₅₀ > 90 µg/mL). Conclusions: Thus, supercritical fluid extraction is an efficient, relatively safe, and cheap technique that yielded a more selective purified extract with better cytotoxic activity.     

Enhanced sampling of bacteria and their biofilms from food contact surfaces with robust cationic modified swabs

The swab sampling method combined with detection approaches is a common approach used to monitor pathogenic microbes in food facilities and to determine the adequateness of regular cleaning and sanitation processes. Thus, the efficiency of a swab material for both the capture and release of bacteria has a significant impact on the detection of pathogens. A novel functionalized cotton swab was developed based on cationic functionalization of the cotton swab for improving the sampling of bacteria from surfaces. The cationic modified swab was fabricated using UV-induced grafting of cationic monomer (METAC) onto a regular cotton swab. The prepared cationic cotton swabs displayed a persistent positive charge regardless of the pH conditions. The cationic swabs demonstrated 150–200% enhancement in the swab performance for Gram-positive and Gram-negative bacteria under any sampling conditions compared to the regular cotton swab as well as a significant enhancement in the bacteria sampling at the low bacterial concentrations. Furthermore, the cationic cotton swabs showed significant improvement at least 4 folds in the sampling performance of the bacterial biofilm from the stainless-steel surfaces compared to the cotton swabs. These results illustrate the role of modified swabs in enhancing the sampling of bacteria from contact surfaces and their potential impact on improved monitoring of microbial contamination and verification of surface sanitization.

     

A Self-Resonant System - Experimental Investigations of Boundary and Operating Conditions

This contribution introduces the setup of a self-resonating system consisting of a freely-sliding mass over a vibrating elastic beam under harmonic excitation. Under specific operating regime, the slider shows tendency to move and adapt its position to where the whole system resonates. The behavior of the slider during that motion is investigated. Experimental observations of the operating regime dependency on some parameters are provided. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Potential Anticancer Activity of the Furanocoumarin Derivative Xanthotoxin Isolated from Ammi majus L. Fruits: In Vitro and In Silico Studies

Ammi majus L., an indigenous plant in Egypt, is widely used in traditional medicine due to its various pharmacological properties. We aimed to evaluate the anticancer properties of Ammi majus fruit methanol extract (AME) against liver cancer and to elucidate the active compound(s) and their mechanisms of action. Three fractions from AME (Hexane, CH₂Cl₂, and EtOAc) were tested for their anticancer activities against HepG2 cell line in vitro (cytotoxicity assay, cell cycle analysis, annexin V-FITC apoptosis assay, and autophagy efflux assay) and in silico (molecular docking). Among the AME fractions, CH₂Cl₂ fraction revealed the most potent cytotoxic activity. The structures of compounds isolated from the CH₂Cl₂ fraction were elucidated using ¹H- and ¹³C-NMR and found that Compound 1 (xanthotoxin) has the strongest cytotoxic activity against HepG2 cells (IC₅₀ 6.9 ± 1.07 µg/mL). Treating HepG2 cells with 6.9 µg/mL of xanthotoxin induced significant changes in the DNA-cell cycle (increases in apoptotic pre-G1 and G2/M phases and a decrease in the S-phase). Xanthotoxin induced significant increase in Annexin-V-positive HepG2 cells both at the early and late stages of apoptosis, as well as a significant decrease in autophagic flux in cancer compared with control cells. In silico analysis of xanthotoxin against the DNA-relaxing enzyme topoisomease II (PDB code: 3QX3) revealed strong interaction with the key amino acid Asp479 in a similar fashion to that of the co-crystallized inhibitor (etoposide), implying that xanthotoxin has a potential of a broad-spectrum anticancer activity. Our results indicate that xanthotoxin exhibits anticancer effects with good biocompatibility toward normal human cells. Further studies are needed to optimize its antitumor efficacy, toxicity, solubility, and pharmacokinetics.     

Calorimetric and spectrophotometric investigation of PLGA nanoparticles and their complex with DNA

The calorimetric investigation of non-coated and chitosan-coated PLGA nanoparticles (NP) shows that at initial temperatures of heating particle swelling takes place what results in an internal architectural change at lower than physiological temperature. It has shown that the temperature of NP tightness perturbing depends on solvent polarity: as more polar is the solvent more stable are particles. The break of existing bonds in NP shell is accompanied with heat absorption peak which undergoes significant changes depending on heating rate. In the wide pH 2–8 interval in transition temperature no changes occurred. The obtained results show that such NP could be used in acidic area for drug transfer, which gives possibility to take medicine orally. It was shown that DNA attaches only to chitosan-coated NP. The optimal ratio for DNA loading onto the NP was found to be 7:1 (W_NP/W_DNA).     

A route to dicyanomethylene pyridines and substituted benzonitriles utilizing malononitrile dimer as a precursor

The conditions of the reaction of malononitrile dimer with enaminones and arylidenemalononitrile could be adapted to yield either pyridines or benzene derivatives. A new synthesis of pyrido[1,2-a]pyrimidines from the reaction of malononitrile dimer 1 and 2-phenyl-3-piperidin-1-yl-acrylonitrile (11) is described. Compound 1 condensed with DMFDMA to yield an enaminonitrile that reacted with hydrazine hydrate to yield N',4,6-triamino-2H-pyrazolo[3,4-b]pyridine-5-carboxamidine (17).     

Thin layer chromatography–densitometric determination of some non‐sedating antihistamines in combination with pseudoephedrine or acetaminophen in synthetic mixtures and in pharmaceutical formulations

The combination of certain non‐sedating antihistamines (NSA) such as fexofenadine (FXD), ketotifen (KET) and loratadine (LOR) with pseudoephedrine (PSE) or acetaminophen (ACE) is widely used in the treatment of allergic rhinitis, conjunctivitis and chronic urticaria. A rapid, simple, selective and precise densitometric method was developed and validated for simultaneous estimation of six synthetic binary mixtures and their pharmaceutical dosage forms. The method employed thin layer chromatography aluminum plates precoated with silica gel G 60 F₂₅₄ as the stationary phase. The mobile phases chosen for development gave compact bands for the mixtures FXD–PSE (I), KET–PSE (II), LOR–PSE (III), FXD–ACE (IV), KET–ACE (V) and LOR–ACE (VI) [Retardation factor (R_f) values were (0.20, 0.32), (0.69, 0.34), (0.79, 0.13), (0.36, 0.70), (0.51, 0.30) and (0.76, 0.26), respectively]. Spectrodensitometric scanning integration was performed at 217, 218, 218, 233, 272 and 251 nm for the mixtures I–VI, respectively. The linear regression data for the calibration plots showed an excellent linear relationship. The method was validated for precision, accuracy, robustness and recovery. Limits of detection and quantitation were calculated. Statistical analysis proved that the method is reproducible and selective for the simultaneous estimation of these binary mixtures. Copyright © 2013 John Wiley & Sons, Ltd.