Gel Plates Research Articles

Phytochemical Screening and High-performance Thin-layer Chromatography Quantification of Vitex trifolia Leaves Hydro-alcoholic Extract: Potential Anti-inflammatory Properties

Aims: The present study aims to evaluate the phytochemical composition of Vitex trifolia (V. trifolia) leaves hydro-alcoholic extract and to report for the first time, its phenolic content using a validated high-performance thin-layer chromatography (HPTLC) method.
 Study Design: Qualitative phytochemical analysis and HTLC densitometric quantitative analysis.
 Place and Duration of Study: The study was carried out at the Faculty of Pharmacy, Universiti Teknologi MARA (UiTM), Malaysia, from March 2020 to December 2020.
 Methodology: The preliminary phytochemical screening was carried out qualitatively. The HPTLC analysis was performed on glass-backed 60 F254 silica gel plates using a two steps gradient elution method of the mobile phase. In the first step, methanol was used to develop the plates until 40 mm of developing distance, while in the second step, plates were developed with n-hexane:ethyl acetate:acetic acid (20:9:1, v/v/v) until 80 mm of developing distance. Detection and quantification were performed by densitometric analysis at 254 nm. The method was validated as per the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guideline in terms of linearity, precision, accuracy, the limit of detection (LOD), and the limit of quantification (LOQ).
 Results: The preliminary phytochemical screening of V. trifolia leaves hydro-alcoholic extract showed the presence of alkaloids, flavonoids, phenols, phytosterols, and terpenoids. The developed HPTLC method was proved to be linear, precise, and accurate. The LOD and LOQ of the method were determined to be 2.01 µg/band and 6.08 µg/band, respectively. The total phenolic content of the extract was calculated from the standard gallic acid calibration plot and found to be 136.94 ± 4.02 mg gallic acid equivalent (GAE)/g of dried extract.
 Conclusion: This preliminary study revealed that V. trifolia has a considerable amount of phenolic compounds, which can potentially contribute to its anti-inflammatory, antioxidant, and anticancer activities. Further pharmacological investigations are being carried out to support the folkloric claims.

Correction to: Densitometric high‑performance thin‑layer chromatography methods for the quantification of oleuropein in Olea europaea leaves and pharmaceutical preparation utilizing normal‑ and reversed‑phase silica gel plates

Correction to: Densitometric high‑performance thin‑layer chromatography methods for the quantification of oleuropein in Olea europaea leaves and pharmaceutical preparation utilizing normal‑ and reversed‑phase silica gel plates

Application of the TLC image analysis technique for the simultaneous quantitative determination of L-proline and L-lysine in dietary supplement

A simple and sensitive thin-layer chromatography (TLC) method coupled with an image analysis technique was developed for the simultaneous quantitative determination of L-proline and L-lysine in dietary supplement with good precision and accuracy. Separation was performed on silica gel plates using ethanol‒toluene (2:3, V/V) as the mobile phase. The visualization of chromatograms was based on iodine–azide reaction; therefore, pre-chromatographic derivatization reaction of amino acids with phenyl isothiocyanate was performed. Digital images of TLC plate chromatograms were converted into peak chromatograms, and quantitative analysis was conducted using TLSee software.

Implementation of Two Chromatographic Methods for Simultaneous Quantitation of Thioctic Acid, Benfotiamine and Cyanocobalamin.

Two accurate and sensitive chromatographic methods have been introduced and validated for the simultaneous determination of thioctic acid, benfotiamine and cyanocobalamin in bulk powders and in their pharmaceutical formulation. Method A is reversed-phase ultra performance liquid chromatographic method with an isocratic elution, where a rapid separation was accomplished on a Zorbax C8 column using a mobile phase of acetonitrile:0.05 M phosphate buffer (pH 6 adjusted by o-phosphoric acid) (23:77, v/v). The retention times (tR) were 0.578, 0.852 and 1.376 for cyanocobalamin, benfotiamine and thioctic acid, respectively. The separated peaks were revealed at 210.0 nm. Method B is a thin-layer densitometric method where the separation of the studied drugs was carried out on silica gel plates using methanol-chloroform-heptane-1-sulphonic acid sodium salt (0.4%) (7:3:0.1, by volume) as a mobile phase, and scanning of the separated bands was done at 240.0 nm. The retardation factor (Rf) values were 0.17, 0.48 and 0.75 for cyanocobalamin, benfotiamine and thioctic acid, respectively. Validation of the methods was achieved following ICH guidelines and the applied methods succeeded to determine the cited drugs in their pure forms and capsules. Results were statistically compared to the manufacturer's method where no significant difference was observed.

Simple and robust differentiation of Ganoderma species by high performance thin-layer chromatography coupled with single quadrupole mass spectrometry QDa.

In this study, a high performance thin-layer chromatography/single quadrupole mass spectrometry QDa (HPTLC-QDa) method for robust authentication of Ganoderma lucidum, a popular and valuable herbal medicine, has been developed. This method is simple and practical, which allows direct generation of characteristic mass spectra from the HPTLC plates automatically with the application of in situ solvent desorption interface. The HPTLC silica gel plates were developed with toluene-ethyl formate-formic acid (5 : 5 : 0.2, V/V) and all bands were transferred to QDa system directly in situ using 80% methanol with 0.1% formic acid as desorption solvent. The acquired HPTLC-QDa spectra showed that luminous yellow band b3, containing ganoderic acid B/G/H and ganodeneric acid B, the major active components of Ganoderma, could be found only in G. lucidum and G. lucidum (Antler-shaped), but not in G. sinense and G. applanatum. Moreover, bands b13 and b14 with m/z 475/477 and m/z 475/491/495, respectively, could be detected in G. lucidum (Antler-shaped), but not in G. lucidum, thus allowing simple and robust authentication of G. lucidum with confused species. This method is proved to be simple, practical and reproducible, which can be extended to analyze other herbal medicines.

Evaluation of antioxidant and anticancer activity of crude extract and different fractions of Chlorella vulgaris axenic culture grown under various concentrations of copper ions

BackgroundChlorella vulgaris is a microalga potentially used for pharmaceutical, animal feed, food supplement, aquaculture and cosmetics. The current study aims to study the antioxidant and prooxidant effect of Chlorella vulgaris cultivated under various conc. of copper ions.MethodsThe axenic green microalgal culture of Chlorella vulgaris was subjected to copper stress conditions (0.00, 0.079, 0.158, 0.316 and 0.632 mg/L). The growth rate was measured at OD680 nm and by dry weight (DW). Moreover, the Antioxidant activity against DPPH and ABTS radical, pigments and phytochemical compounds of the crude extracts (methylene chloride: Methanol, 1:1) were evaluated. The promising Cu crude extract (0.316 mg/L) further fractionated into twenty-one fractions by silica gel column chromatography using hexane, chloroform and ethyl acetate as a mobile phase.ResultsThe obtained results reported that nine out of these fractions exhibited more than 50% antioxidant activity and anticancer activity against Hela cancer cell lines. Based on IC50, fraction No. 7 was found to be the most effective fraction possessing a significant increase in both antioxidant and anticancer potency. Separation of active compound (s) in fraction No 7 was performed using precoated silica gel plates (TLC F254) with ethyl acetate: hexane (9:1 v/v) as mobile phase. Confirmation of active compound separation was achieved by two-dimensional TLC and visualization of the separated compound by UV lamp. The complete identification of the separated active compound was performed by UV- Vis- spectrophotometric absorption, IR, MS, H1-NMRT C13-NMR. The isolated compound ((2E,7R,11R)-3,7,11,15-Tetramethyl-2-hexadecenol) have high antioxidant activity with IC50 (10.59 μg/ml) against DPPH radical assay and comparable to the capacities of the positive controls, Butylated hydroxy toluene [BHT] (IC50 11.2 μg/ml) and Vitamin C (IC50 12.9 μg/ml). Furthermore, pure isolated compound exhibited a potent anticancer activity against Hela cell line with IC50 (4.38 μg/ml) compared to Doxorubicin (DOX) as synthetic drug (13.3 μg/ml). In addition, the interaction of the pure compound with Hela cancer cell line and gene expression were evaluated.ConclusionsThe authors recommend cultivation of Chlorella vulgaris in large scale under various stress conditions for use the crude extracts and semi purified fractions for making a pharmaco-economic value in Egypt and other countries.

Development and Validation of Two Novel Chromatographic Methods: HPTLC and HPLC for Determination of Bromhexine Hydrochloride in Presence of Its Two Impurities.

Two simple, sensitive and validated chromatographic methods were developed for quantitative determination of bromhexine hydrochloride (BHX) in presence of its major impurities, impurity B (IMB) and impurity C (IMC), as specified by British Pharmacopoeia. First method (I) was high-performance thin layer chromatography-densitometry at which the chromatographic separation was performed using silica gel plates and developing system consisted of hexane:acetone:ammonia solution (9:0.5:0.08, by volume) with ultraviolet scanning at 240nm and linearity was achieved in the ranges of 0.40-10.00, 0.20-2.00 and 0.20-2.00μg/band of BHX, IMB and IMC, respectively. Also, second chromatographic method (II) was high-performance liquid chromatography (HPLC) where the separation was carried out on C18 column at isocratic mode at flow rate 1.5mL/min. The mobile phase consisted of methanol:water (90:10, v/v) adjusted to pH2.5 with O-phosphoric acid and temperature was adjusted to 40°C. The scanning wavelength was 240nm. The chromatographic run time was 6min. Linearity of this method was achieved in the ranges of 4.00-40.00, 0.20-10.00 and 0.50-10.00μg/mL for BHX, IMB and IMC, respectively. The validation of these chromatographic methods was made according to International Conference on Harmonization guidelines. These methods were successfully applied for determination of BHX in its pharmaceutical formulation. Also, statistical comparison was attained between the developed methods and the reported HPLC method using Student's t-test and F-test, and the obtained results showed that there was not any significant difference between them concerning with accuracy and precision.

A high-throughput ultrasonic spraying inoculation method promotes colony cultivation of rare microbial species.

Current method for obtaining microbial colonies still relies on traditional dilution and spreading plate (DSP) procedures, which is labor-intensive, skill-dependent, low-throughput and inevitably causing dilution-to-extinction of rare microorganisms. Herein, we proposed a novel ultrasonic spraying inoculation (USI) method that disperses microbial suspensions into millions of aerosols containing single cells, which lately be deposited freely on a gel plate to achieve high-throughput culturing of colonies. Compared with DSP, USI significantly increased both distributing uniformity and throughput of the colonies on agar plates, improving the minimal colony-forming abundance of rare Escherichia coli mixed in a lake sample from 1% to 0.01%. Applying this novel USI to a lake sample, 16 cellulose-degrading colonies were screened out among 4766 colonies on an enlarged 150-mm-diameter LB plate. Meanwhile, they could only be occasionally observed when using commonly used DSP procedures. 16S rRNA sequencing further showed that USI increased colony-forming species from 11 (by DSP) to 23, including seven completely undetectable microorganisms in DSP-reared communities. In addition to avoidance of dilution-to-extinction, operation-friendly USI efficiently inoculated microbial samples on the agar plate in a high-throughput and single-cell form, which eliminated masking or out-competition from other species in associated groups, thereby improving rare species cultivability.

HPTLC-Densitometry Screening and Mass Identification of Fluorescent Whitening Agents Contamination in Cereal Flour

In recent years, there was increasing concerns on food safety issues associated with fluorescent whitening agents from package materials. Here, we reported the development of a facile and reliable method suitable for high-throughput quantification and identification of two common fluorescent whitening agents (FWA 184 and FWA 367) in cereal products (wheat and rice flour), platformed by high-performance thin-layer chromatography. First, the sample preparation and cleanup were rapidly accomplished via an optimized solid–liquid extraction. The extracts and reference standard were simultaneously separated on silica gel plates, using the mixture of toluene and ethyl acetate (10/0.3, v/v) as the mobile phase. Then, rapid quantification was performed with densitometry in fluorescent mode (365 </ 400 nm, mercury lamp), reaching limit of detection 18–21 μg/kg; meanwhile, good linearity (R2 = 0.9999) of quantification can be achieved within a broad range (100–2000 pg/band). With real cereal samples, the quantitative measurement was validated, showing good spike-recovery rates (88.0–108.4%). Furthermore, the conclusive identification of the targeted band was directly realized by in situ mass detection, providing compound-specific signals (m/z 363.09 and 431.18, for FWA 184 and FWA 369, respectively) as the fingerprint evidence. The proof-of-concept result of this work demonstrated that HPTLC as a versatile analytical platform can achieve an ideal balance among throughput, simplicity, and detectability, therefore, particularly suitable for screen-oriented food analysis.

Simple Methods for the Preparation of Colloidal Chitin, Cell Free Supernatant and Estimation of Laminarinase.

Colloidal chitin (CC) is a common substrate used in research work involving chitin-active enzymes (chitinases). Cell free supernatant (CFS) is prepared from fermented broth. Preparation of CC and CFS usually involve large amounts of liquid, which must be separated from the solids. This necessitates the use of a large volume centrifugation facility, which may not be accessible to everyone. Filtration is a viable alternative to centrifugation, and several filter elements are described in the literature. Each of those elements has its own set of disadvantages like non-availability, high cost, fragility, and non-reusability. Here we describe the use of lab coat clothing material (LCCM) for the preparation of CC and CFS. For filtration purposes, the LCCM was found to be functional, rugged, reusable, and cost-effective. Also described here is a new method for the estimation of laminarinase using a laminarin infused agarose gel plate. An easily available optical fabric brightener (OFB) was used as a stain for the agarose plate. The laminarin infused agarose plate assay is simple, inexpensive, and was found to be impervious to high amounts of ammonium sulfate (AS) in enzyme precipitates.

Simultaneous Analytical Efficiency Evaluation Using an HPTLC Method for the Analysis of Syringic Acid and Vanillic Acid and Their Anti-Oxidant Capacity from Methanol Extract of Ricinus communis L. and Euphorbia hirta L.

The well-known medicinal plants Ricinus communis L. and Euphorbia hirta L. have been traditionally used to treat a variety of ailments in the India and other countries. In the present research, a simple, rapid, reliable, and accessible HPTLC technique has been established for concurrent quantification of phenolic compounds (syringic acid and vanillic acid) and evaluation of their anti-oxidant capacity. The chromatographic separation was conceded on pre-coated silica gel plates 60 F254 as the stationary phase. The appropriate mobile phase combination of toluene-ethyl acetate-formic acid (7:2.5:0.5, v/v/v) were developed to expand the plates which separated components according to the marker compounds. Further, the anti-oxidant potential of methanol extract of R. communis (MERC) and E. hirta (MERH) were also assessed with 1,1-diphenyl-2-picrylhydrazyl (DPPH) by using UV spectrophotometry. Densitometric scanning was performed with a Camag V scanner and measured at two different wave lengths, 272 and 318 nm. The marker compounds were practically resolved with RF 0.5 ± 0.04 for syringic acid and 0.6 ± 0.06 for vanillic acid. The results obtained in the study of anti-oxidant activity of MERC and MERH showed significant free radical scavenging capacity against DPPH-generated free radicals. The developed HPTLC method was validated for accuracy, linearity, precision, and specificity. Both the extracts revealed considerable antioxidant activity. The reported existing phenolic and flavonoids compounds are responsible for antioxidant activity of plant extracts.

Off-line multidimensional high performance thin-layer chromatography for fractionation of Japanese knotweed rhizome bark extract and isolation of flavan-3-ols, proanthocyanidins and anthraquinones

A methodology based on off-line multidimensional thin-layer chromatography was developed for isolation of several secondary metabolites from bark of Japanese knotweed (Fallopia japonica Houtt.) rhizomes. Successive fractionation steps using PLC silica gel and HPTLC silica gel or HPTLC cellulose plates in combination with various developing solvents enabled isolation of (+)-catechin, (-)-epicatechin, (-)-epicatechin gallate, procyanidin B1, procyanidin B2, procyanidin B3, proanthocyanidin B dimer gallate, emodin, emodin-8-O-glucoside and emodin-8-O-malonyl-glucoside. Their identity was confirmed by HPTLC, HPTLC-MSn and for most of them also by 1H NMR and 2D NMR analyses. To the best of our knowledge emodin-8-O-malonyl-glucoside, procyanidins B1 and B2 were for the first time isolated from this plant material. HPTLC and HPTLC-MSn analyses were also performed as support of fractionation/isolation process, leading to first detection of some compounds in bark of Japanese knotweed rhizomes and Japanese knotweed rhizomes in general: procyanidins B1 and B2, methyl derivatives of emodin bianthrone and emodin bianthrone-hexose, resveratrol-malonyl-hexoside and taxifolin derivatives. Characterization of flavan-3-ols and proanthocyanidins was facilitated by post-chromatographic derivatization of the corresponding chromatographic zones with 4-dimethylaminocinnamaldehyde (DMACA) detection reagent.

3D printed portable gel electrophoresis device for rapid detection of proteins

The growing demand for rapid, portable, and economical detection methods for environmental analysis has resulted in increasing demands on the portability and miniaturization of analytical instruments. The miniaturization of scientific instruments facilitates analysis in the field of medicine, food, and environment, especially for the under-resourced areas. The gel electrophoresis devices currently available for protein separation are primarily used in laboratories. Miniaturized instruments that can be used for on-site and rapid separation of protein have not yet been reported. In this study, a portable gel electrophoresis device for rapid separation and detection of proteins was developed and manufactured by 3D printing in a laboratory, which was economical, convenient, and quick. First, four kinds of portable gel electrophoresis devices that included three kinds of columnar gel and one slab gel electrophoresis device were designed with computer-aided design software SolidWorks 2017 (Dassault Systemes SE, France); the components including gel tubes, gel plates, and gel electrophoresis tanks were then printed using a 3D printer after optimization of the printing parameters. Then, the performance of the four kinds of gel electrophoresis devices was investigated using prestained protein molecular weight standards. The results showed that the single-channel slab gel electrophoresis design can quickly separate proteins with the best separation efficiency. Moreover, the effect of different separation gel lengths (5, 10, 15, and 20 mm) on protein separation was studied and it was found that 10% separation gels with a length of 5 mm could effectively separate prestained protein molecular weight standards (in the range of 15-250 kD) in 20 minutes. Next, the battery was optimized for the portable GE device and a 25 V lithium battery (70 mm×60 mm×40 mm) was used as the power supply, which could provide a constant voltage of 25 V for 100 hours during gel electrophoresis. Then, the One-Step BlueTM reagent (Biotium, USA) was used to color the separation results of the five standard proteins (carbonic anhydrase, ovalbumin, bovine serum albumin, conalbumin, ribonuclease A), and the results were recorded by mobile phone. Finally, the proposed gel electrophoresis device was compared with the commercial device. The results showed that the two devices are comparable; however, the slab gel electrophoresis was faster, portable, and economical. In summary, this research designed and manufactured a portable gel electrophoresis device using 3D printing technique, which can be used for on-site analysis and detection of proteins. The device presents the following advantages compared with the commercial devices:1) small and portable:the size of the electrophoresis tank of the device is only 15 mm×20 mm×17 mm and the 25 V lithium battery has a working time of approximately 100 hours; 2) low cost:it can be processed in 5 hours using 3D printing technology, with 10 mL of printing material while the total cost is less than 400 RMB; 3) fast separation:this device can quickly achieve protein separation compared with commercial devices and can further use multiple electrophoresis tanks in parallel to analyze more samples at the same time. Besides, this research also highlights the advantages of 3D printing for the development of miniaturized analytical equipment. Though this study has achieved preliminary results for rapid separation of proteins using gel electrophoresis devices, the quantitative analysis of proteins following protein detection and the application of more samples need further research. Meanwhile, the continued application of 3D printing technology will promote the development of miniaturized and portable experimental equipment.

Extraction of Anthraquinones from Japanese Knotweed Rhizomes and Their Analyses by High Performance Thin-Layer Chromatography and Mass Spectrometry.

Anthraquinones (yellow dyes) were extracted from Japanese knotweed rhizomes with twelve extraction solvents (water; ethanol(aq) (20%, 40%, 60%, 70% and 80%), ethanol, 70% methanol(aq), methanol, 70% acetone(aq), acetone and dichloromethane). The obtained sample test solutions (STSs) were analyzed using high-performance thin-layer chromatography (HPTLC) coupled to densitometry and mass spectrometry (HPTLC–MS/MS) on HPTLC silica gel plates. Identical qualitative densitometric profiles (with anthraquinone aglycones and glycosylated anthraquinones) were obtained for STSs in all the solvents except for the STS in dichloromethane, which enabled the most selective extractions of anthraquinone aglycones emodin and physcion. The highest extraction efficiency, evaluated by comparison of the total peak areas in the densitograms of all STSs scanned at 442 nm, was achieved for 70% acetone(aq). In STS prepared with 70% acetone(aq), the separation of non-glycosylated and glycosylated anthraquinones was achieved with developing solvents toluene–acetone–formic acid (6:6:1, 3:6:1 and 3:3:1 v/v) and dichloromethane–acetone–formic acid (1:1:0.1, v/v). Non-glycosylated anthraquinones were separated only with toluene–acetone–formic acid, among which the best resolution between emodin and physcion gave the ratio 6:6:1 (v/v). This solvent and dichloromethane–acetone–formic acid (1:1:0.1, v/v) enabled the best separation of glycosylated anthraquinones. Four HPTLC-MS/MS methods enabled the identification of emodin and tentative identification of its three glycosylated analogs (emodin-8-O-hexoside, emodin-O-acetyl-hexoside and emodin-O-malonyl-hexoside), while only the HPTLC-MS/MS method with toluene-acetone-formic acid (6:6:1, v/v) enabled the identification of physcion. Changes of the shapes and the absorption maxima (bathochromic shifts) in the absorption spectra after post-chromatographic derivatization provided additional proof for the detection of physcion and rejection of the presence of chrysophanol in STS.

A Theoretical Study on the Transient Morphing of Linear Poroelastic Plates

Abstract Based on their shape-shifting capabilities, soft active materials have enabled new possibilities for the engineering of sensing and actuation devices. While the relation between active strains and emergent equilibrium shapes has been fully characterized, the transient morphing of thin structures is a rather unexplored topic. Here, we focus on polymer gel plates and derive a reduced linear model to study their time-dependent response to changes in the fluid environment. We show that independent control of stretching and bending deformations in stress-free conditions allows to realize spherical shapes with prescribed geometry of the mid-plane. Furthermore, we demonstrate that tensile (compressive) membrane stresses delay (accelerate) swelling-induced shape transitions compared to the stress-free evolution. We believe that these effects should be considered for the accurate design of smart systems and may contribute to explain the complexity of natural shapes.

Physico-mechanical properties and SEM of sol–gel plates based on chitosan L-(D-)ascorbate

In our previous studies, it was shown that the isomeric form of ascorbic acid (L-or D-AscA) used to obtain the salt form of chitosan had a significant effect on the total space charge, size and general chirality of chitosan ascorbate macromolecules in solution, their stereomeric ordering in lyophilically isolated solid phase, as well as the kinetics of sol–gel synthesis of materials based thereon. This study examines the effect of L- and D-AscA on the physico-mechanical and morphological properties of thin-film sol–gel plates based on chitosan L-or D-ascorbate without and with Aloe Vera juice added. It has been established that the AscA isoform has a significant effect on the elastoplastic characteristics of the samples and the surface relief of their solid phase. The addition of Aloe Vera also leads to significant texturing of the surface relief. The latter could be used to design specific optical sensors and optodes of medico-biological purposes.

Densitometric high-performance thin-layer chromatography methods for the quantification of oleuropein in Olea europaea leaves and pharmaceutical preparation utilizing normal- and reversed-phase silica gel plates

Densitometric high-performance thin-layer chromatography methods for the quantification of oleuropein in Olea europaea leaves and pharmaceutical preparation utilizing normal- and reversed-phase silica gel plates

Wafer-Scale Growth of Pristine and Doped Monolayer MoS2 Films for Electronic Device Applications

Scalable production and controlled doping of large-area two-dimensional transition-metal dichalcogenide films are fundamental steps toward their applications in electronic devices. Although a variety of methods for preparation of wafer-scale transition-metal dichalcogenide films have been developed, it is still challenging to realize homogeneous doping of the large-area films to modulate their electronic properties. In this paper, we report a new chemical vapor deposition (CVD) method for preparation of wafer-scale pristine and doped monolayer MoS2 films on 2-inch sapphire wafers. The molybdenum precursors are supplied in a "face-to-face" manner from a silica gel plate to the sapphire wafer, which guarantees uniform nucleation and growth of monolayer MoS2. This method can be used to prepare substitutionally doped monolayer MoS2 films. By using ReCl3 as the dopant precursor, we have obtained continuous Re-doped monolayer MoS2 films on sapphire wafers. Elemental analysis confirms successful Re-doping of the MoS2 film. Spherical aberration-corrected scanning transmission electron microscopy characterization reveals that the Re atoms are incorporated at the substitutional Mo sites in the MoS2 lattice. The incorporation of Re atoms leads to n-type doping of MoS2 as evidenced by Kelvin probe force microscope studies. Electrical measurements reveal that the transport properties of the Re-doped monolayer MoS2 is dramatically enhanced as compared with the pristine MoS2. The CVD method developed in this study can be applied to the production of a variety of two-dimensional transition-metal dichalcogenide films suitable for applications in electronic devices.

Ecofriendly Validated Chromatographic Methods for Quantitation of Cyclizine and Its Toxic Impurities in Its Parenteral Formulation

Cyclizine (CYZ) abuse is commonly reported, either through oral or intravenous routes, for its euphoric or hallucinatory effects. The concomitant misuse of CYZ among addicted teenagers leads to life-threatening neuromuscular disorders. Consequently, two green and validated chromatographic methods were developed for the determination of CYZ, an antiemetic drug, in its parenteral formulation in the presence of 1-methyl piperazine and diphenylmethanol (benzhydrol) as the pharmacopeial stated impurities of CYZ. The first method was TLC-densitometry that relied on using a mixture consisting of ethyl acetate:isopropanol:ammonia (9.5:1:0.5, by volume) as a developing system, TLC 60 F254 silica gel plates as a stationary phase and detection of the scanned bands was performed at 210.0 nm. On the other hand, the second method was UPLC which based on the separation of CYZ and its impurities using a mobile phase consisting of ethanol and acidic water at pH 5 adjusted by phosphoric acid in the ratio of (60:40, %v/v) at flow rate 0.2 mL min−1 and UV detection were carried out at 210.0 nm. The greenness profile of the established methods was evaluated and calculated for the first time for CYZ and its toxic impurities through different assessment tools like analytical eco-scale, analytical method volume intensity and greenness profile methods. Validation of the developed methods was carried out in accordance with the guidelines of the International Conference on Harmonization. The suggested methods were accurate, reliable, time and cost-saving. Therefore, they could be used in quantification of CYZ abuse and its toxic impurities in parenteral formulation for routine quality control. The results achieved by applying the suggested methods were statistically analyzed and compared with those given by reported one and no significant differences were obtained regarding both precision and accuracy.

Analgesia for Pediatric Arteriovenous Fistula Cannulation in Hemodialytic Patients: A Comparison of Lidocaine Gel, Lidocaine Spray, and Needle Plate.

Background:Children undergoing hemodialysis (HD) via arteriovenous fistula (AVF) experience approximately 300 painful punctures per year which may lead to non-compliance with HD. This study was conducted to show the effect of local anesthetics on pain perception in AVF cannulation.Methods:This randomized clinical trial included 20 children under HD via AVF in Sheikh Children's Hospital Hemodialysis Center in February 2014. The first intervention was conducted as the baseline pain assessment (control), then every patient randomly received all three other interventions: Lidocaine gel, lidocaine spray, and needle plate, before venipuncture. Pain perception was expressed and recorded by patients using the visual analogue scale (VAS). VAS scores were compared, and a P value of <0.05 was considered significant.Results:The VAS mean in lidocaine spray state, lidocaine gel state, and needle plate state was respectively 47.87, 51.31, and 49.43, which were significantly less than the control state with the VAS mean of 60.06 (lidocaine spray vs. control P value = 0.001, lidocaine gel vs. control P value = 0.001, and needle plate vs. control P value = 0.003).Conclusion:Our study showed that the use of needle plate, lidocaine spray, and lidocaine gel are all equally effective ways in controlling the degree of pain in AVF needling in children undergoing HD.