Ascorbic Acid In Aqueous Solution Research Articles

Development and validation of the method of quantification of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide and its metabolites in laboratory animal plasma

Introduction. The study of the systemic exposure of a new original drug is an essential part of its preclinical study. 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide is a new selective carbonic anhydrase II inhibitor for the treatment of open-angle glaucoma. Methods for the quantitative determination of this compound and its N-hydroxy- and N-acetyl metabolites in the plasma of laboratory animals have not been previously developed.Aim. Development and validation of a method of quantitative determination of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide and its metabolites N-hydroxy-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide (M1) and N-acetyl-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide (M2) in rat and rabbit blood plasma by HPLC-MS/MS.Materials and methods. Protein precipitation by methanol was applied for sample preparation. 5-[2-(morpholine-4-carbonyl)-1,3-oxazole-5-yl]-thiophene-2-sulfonamide was used as an internal standard. A 5 % aqueous solution of ascorbic acid was added to the plasma samples at volume ratio 1 : 2 to prevent decomposition of N-hydroxy-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide. The combination of sodium fluoride and potassium oxalate was selected as an anticoagulant. Chromatographic separation was performed on Zorbax Eclipse Plus C18 column (150 × 3.0 mm, 3.5 µm) with Zorbax Eclipse Plus C18 pre-column (12.5 × 2.1 mm, 5.0 µm) using a mobile phase based on a 0.1 % aqueous solution of formic acid and methanol. Mass spectrometric detection was carried out in the MRM mode using electrospray ionization in negative polarity. The method was tested during a pharmacokinetic study of a 1 % ocular suspension of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide on 6 Wistar rats. Blood samples were collected before administration, as well as 30 min, 1 h, 1 h 30 min, 2 h, 3 h, 4 h, 6 h, 8 h, 12 h, 24 h, 48 h, 72 h, 144 h, 216 h after administration. The non-compartment approach was used for calculation pharmacokinetic parameters.Results and discussion. The developed method has been validated in parameters of selectivity, calibration curve, accuracy and precision, matrix effect, dilution integrity, carry over, reinjection reproducibility, stability. The analytical range of determination of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide in plasma was 10–4000 ng/ml, M1 – 1.0–400.0 ng/ml, M2 – 0.1–40.0 ng/ml. The selected combination of anticoagulant and stabilizer solution allows storage of plasma samples in freezing chamber for 28 days.Conclusion. The developed method has been fully validated and confirmed its suitability for quantitative determination of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide and its metabolites in the blood plasma of laboratory animals. The method has been successfully used for pharmacokinetic study of 1 % ocular suspension of the drug.

Potential of Bioactive Protein and Protein Hydrolysate from Apis mellifera Larvae as Cosmeceutical Active Ingredients for Anti-Skin Aging.

This study aimed to extract bioactive proteins and protein hydrolysates from Apis mellifera larvae and assess their potential application in cosmetics as well as their irritation properties. The larvae were defatted and extracted using various mediums, including DI water, along with 0.5 M aqueous solutions of sodium hydroxide, ascorbic acid, citric acid, and hydrochloric acid. Subsequently, the crude proteins were hydrolyzed using the Alcalase® enzyme. All extracts underwent testing for antioxidant activities via the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and Griess assays. Anti-aging properties were evaluated in terms of anti-collagenase and anti-hyaluronidase effects. Irritation potential was assessed using the hen's egg chorioallantoic membrane (HET-CAM) test. The results revealed that the sodium hydroxide extraction showed promising outcomes in terms of yield, protein content, and effectiveness in inhibiting hyaluronidase, with the highest inhibition at 78.1 ± 1.5%, comparable to that of oleanolic acid. Conversely, crude protein extracted with ascorbic acid and its hydrolysate showed notable antioxidant and collagenase-inhibitory activities. Remarkably, their anti-collagenase effects were comparable to those of ascorbic acid and lysine. Additionally, it demonstrated safety upon testing with the CAM. In conclusion, the findings provided valuable insights into the utilization of A. mellifera larval proteins as active ingredients with a wide range of cosmeceutical applications, particularly due to their antioxidant, anti-aging, and low irritation properties, which hold significant promise for anti-skin wrinkles.

Hybrid copper-polyelectrolyte nanoaggregates obtained with smart block copolymers based on 4-[(hydroxyimino)aldehyde]butyl methacrylate (HIABMA) in water and acetonitrile

The AB multi-stimuli-responsive block copolymer pTEGMA-b-pHIABMA (TEGMA: tetra(ethyleneglycol) methyl ether methacrylate; HIABMA: 4-[(hydroxyimino)aldehyde]butyl methacrylate) comprises a hydrophilic and thermoresponsive PTEGMA block linked to the hydrophobic PHIABMA chain. The latter is endowed with slightly acidic oxime groups that potentially form complexes with metal ions. Here we investigate the formation of hybrid Cu(II)-polymer nanoaggregates both in water and in acetonitrile. Cu(II) ions are quantitatively and rapidly incorporated, in the presence of a base, into pre-formed polymeric core-shell micelles (30 nm diameter by DLS) in water up to 1:2 metal-to-ligand stoichiometry. The pKa of the polymer is decreased from ≅11.2 to 4.65 due to interaction with Cu(II) and the complex is shown to involve oximate ions. The thermoresponsivity of the polymeric micelles remains unchanged with Cu(II) complexation and allows an easy separation by flocculation of the hybrid complex. Moreover, nanoaggregates (D = 20 nm) form in acetonitrile from the fully solubilized copolymer interacting with Cu(OAc)2. The 1:2 Cu(II)/ligand stoichiometry is confirmed with the Job graphical method. Characterization of the hybrid micelles was carried out by UV–Vis spectrometry, DLS, TEM, STEM and SAXS. Quantitative release of Cu(II) in acidic conditions is demonstrated both in water and in acetonitrile. Full recovery of the free metal ions and of intact polymeric micelles is achieved through centrifugal filtration of the aqueous preparation, as a proof-of-concept for a recyclable system for metal uptake and release. Furthermore, Cu0 nanoparticles of 5–10 nm are obtained through reduction of Cu(II) within the micelles with ascorbic acid in aqueous solution.

Noble Metal-Free Light-Driven Hydrogen Evolution Catalysis in Polyampholytic Hydrogel Networks.

Future technologies to harness solar energy and to convert this into chemical energy strongly rely on straightforward approaches to prepare versatile soft matter scaffolds for the immobilization of catalysts and sensitizers in a defined environment. In addition, particularly for light-driven hydrogen evolution, a transition to noble metal-free photosensitizers and catalysts is urgently required. Herein, we report a fully organic light-harvesting soft matter network based on a polyampholyte hydrogel where both photosensitizer (a perylene monoimide derivative) and a H2 evolution catalyst ([Mo3S13]2-) are electrostatically incorporated. The resulting material exhibits sustained visible-light-driven H2 evolution in aqueous ascorbic acid solution, even at rather low loadings of photosensitizer (0.4%) and catalyst (120 ppm). In addition, we provide initial insights into the long-term stability of the hybrid hydrogel. We believe that these results pave the way for a generalized route toward the incorporation of noble metal-free light-driven catalysis in soft matter networks.

Multifunctional Luminescent 3D Ln-MOFs with High Sensitivity for Trace Detection of Micronutrients.

The synthesis of two versatile fluorescent metal-organic frameworks (MOFs), [Eu(4-NCP)(1,4-bdc)]n·0.5H2O (1) and [Eu(4-NCP)(4,4'-bpdc)]n·0.75H2O (2) (HNCP = 2-(4-carboxyphenyl)imidazo(4,5-f)-(1,10)phenanthroline, 1,4-H2bdc = benzene-1,4-dicarboxylic acid, 4,4'-H2bpdc = 4,4'-biphenyldicarboxylic acid), was carried out using a hydrothermal method. These MOFs were characterized through various advanced technologies to determine their structural information. The results indicate that both MOFs exhibited 3D network structures with specific topologies. Furthermore, these MOFs demonstrated exceptional thermal stabilities and adsorption capabilities. Additionally, complex 2 was utilized for studying the fluorescence sensing properties of various micronutrients including metal ions, nitro aromatic compounds, and biological small molecules. Notably, complex 2 showed promising potential as a multifunctional sensor for selectively detecting Fe3+, nitrobenzene, and ascorbic acid in aqueous solutions through fluorescence quenching with low limits of detection (LODs ∼ 10-7 M) and high quenching constants (Ksv ∼ 103 M-1). Moreover, the detection mechanism of complex 2 was further investigated by using experimental methods and DFT calculations.

Antimicrobial and Antioxidant Activity Screening of Mushrooms Growing in the Leningrad Region

Introduction. The emergence of new strains of microorganisms that are multidrug resistant (MDR) in relation to the antimicrobial drugs used is one of the pressing problems of modern medicine. To prevent an increase in MDR-related deaths, the search for new antibiotics and their introduction into medical practice must be continuously ongoing. Infectious diseases are also accompanied by cell damage and the development of free radical oxidation processes, therefore the search for new antioxidants is also an important task. Considering the powerful biosynthetic potential of basidiomycetes, this group of fungi has every prospect of becoming a new source of biologically active substances in general, as well as antibiotics and antioxidants in particular. Cap mushrooms, represented mainly by basidiomycetes, number about 14,000 species and are an accessible source of raw materials for the search for promising antimicrobial compounds and antioxidants.Aim. Study of the antioxidant and antimicrobial activity of total extracts obtained from cap mushrooms against Escherichia coli, Staphylococcus aureus and Candida albicans and assessment of the suitability of cap mushrooms as a natural source of substances with antimicrobial and antioxidant activity.Materials and methods. The antifungal and antibacterial activity of the extracts was determined by the micromethod of two-fold serial dilutions in a liquid nutrient medium in 96-well plates in duplicate. The study of this type of biological activity was carried out against reference (type) strains Staphylococcus aureus ATCC 6538-P, Escherichia coli ATCC 25922, Candida albicans NCTC 885-653. To study antioxidant activity using DPPH, we used alcoholic extracts from the fruiting bodies of mushrooms obtained by maceration with 96 % ethanol at a ratio of raw materials to extractant of 1 to 8 for 24 hours, an aqueous solution of ascorbic acid (vitamin C) and an ethanol solution of Trolox.Result and discussion. In relation to S. aureus, a representative of gram-positive flora, the studied extracts of cap mushrooms showed low activity, on average about 2500 or 5000 μg/ml. In relation to E. coli, a representative of gram-negative flora, 8 % of the studied cap mushroom extracts showed an average activity of about 1250 μg/ml. The largest number of cap mushroom extracts – 19% of all studied species – showed activity against the yeast micromycete C. albicans. The highest activity against C. albicans was observed in extracts of the mushrooms Cantharellula umbonata with an MIC of 625 μg/ml, Cortinarius olivaceofuscus with an MIC of 625 μg/ml, and Hypomyces chrysospermus with an MIC of 312 μg/ml. During screening of antioxidant activity, the studied extracts were divided into three groups: with high (more than 50 % PPR), medium (from 15 to 50 % PPR) and low (less than 15 %) antioxidant activity. It was shown that the sum of phenolic compounds significantly correlates with the level of antioxidant activity in all three groups, but in the groups with medium and low antioxidant activity there are also other non-phenolic groups of compounds that make a significant contribution to the total antioxidant activity.Conclusion. Cap mushrooms are a promising source of biologically active substances with antifungal and antioxidant activity.

Modifying platinum microelectrodes with electrochemically reduced graphene oxide for application in electrochemical ascorbic acid sensor

Graphene oxide drop-casted on a platinum microelectrode was successfully changed to reduced graphene oxide by using a cyclic voltammetry method. The presence of an electrochemically reduced graphene oxide layer on the platinum electrode was proved by using scanning electron microscopy images, Raman and Fourier-transform infrared spectroscopy spectra. Cyclic voltammetry and linear sweep voltammetry results indicated that the platinum microelectrode modified with electrochemically reduced graphene oxide can be used as an electrochemical sensor for detection of ascorbic acid in aqueous solutions. In a cyclic voltammetry scan and a linear sweep voltammetry curve corresponding to the presence of ascorbic acid, a peak related to the direct oxidation of ascorbic acid appears. The electrochemical sensor based on the electrochemically reduced graphene oxide material works effectively with a detection limit of 0.04 mM, a detection linear range from 0.04 mM to 1.0 mM, a good repeatability, and especially, a rapid detection time thanks to a direct ascorbic acid detection based on the oxidation of ascorbic acid.

Multifunctional Cd-CP for fluorescence sensing of Cr(VI), MnO4−, acetylacetone and ascorbic acid in aqueous solutions

The development of multifunctional fluorescent chemosensors for the detection of multiple targets remains challenging but of great importance. In this paper, one novel coordination polymer (CP), denoted as [Cd2(edda)(phen)2]∙H2O (compound 1, H4edda = 5,5′ (ethane-1,2-diylbis(oxy)) diisophthalic acid, phen = 1,10-phenanthroline) is successfully designed and prepared under hydrothermal conditions. Structural analysis indicates that compound 1 possesses a one-dimensional (1D) double chain structure, then self-assembles into a three-dimensional (3D) supramolecular framework via π…π interactions between phen molecules. Interestingly, compound 1 is found to be tolerant in wide range of acidic to alkaline aqueous solutions (pH = 2–13). Fluorescent spectral investigations reveal that compound 1 exhibits highly selective and sensitive fluorescence responses toward MnO4−, Cr(VI) ions, acetylacetone (acac) and ascorbic acid (AA) by fluorescence quenching in the aqueous phase. The detection limits are in the very low range, reaching μM level for the detection of MnO4−, Cr(VI) ions, nM for AA and ppm for acac detection. The distinguished multi-responsive performance suggests compound 1 to be a potential multifunctional probe. Furthermore, the possible quenching mechanisms have also been systematically investigated in this work.

The acceleration of BODIPY dye-sensitized photocatalytic hydrogen production in aqueous ascorbic acid solutions using alkyl-chain formed second coordination sphere effects

Optimizing hydrogen production in ascorbic acid solutions: enhancing BODIPY dye-sensitized processes through alkyl-chain-enhanced second coordination sphere effects.

The Potential of Gadolinium Ascorbate Nanoparticles as a Safer Contrast Agent.

There have been health concerns raised against the use of gadolinium (Gd)-based magnetic resonance imaging contrast agents. The primary observation is that Gd ions are prone to leaking into the bloodstream, causing nephrogenic systemic fibrosis as one of the side effects. In addition, such leakage of the ions inhibits easy clearance from the body. Herein we propose that Gd-ascorbate nanoparticles could be one of the safer choices as they are rather stable in aqueous dispersion and they do not get affected by Zn or Fe ions in the medium. The magnetic properties of the ions are preserved in the nanoparticles, and particles when sufficiently small may be amenable to renal clearance from the human body. Thus, when an aqueous solution of Gd-acetate and ascorbic acid was left to evolve with time, a Gd-ascorbate complex was formed that led to the formation of nanoparticles with time. The sizes of the nanoparticles increased with time, and when the particles were sufficiently large, they precipitated out of the medium. In addition, smaller nanoparticles were consistently present at all times of observations. UV-vis, photoluminescence and FTIR spectroscopy, mass spectrometry, and transmission electron microscopy analyses confirmed the formation of nanoparticles of Gd-ascorbate complex. In addition, magnetic measurements confirmed the high relaxivity of the nanoparticles as compared to the parent salt, indicating the effectiveness of the nanoparticles as contrast agents. Density functional theory-based calculations of the molecular complex-based nanoparticles accounted for the experimental observations.

Molecular interaction studies on the binding ability of hydrated zinc sulphate with aqueous solution of ascorbic acid at different temperatures

Abstract The ternary systems containing Water, Ascorbic acid (AA) and ZnSO4·7H2O were investigated using three approaches namely volumetric studies, viscosity studies and conductance studies. The solvent systems used were 2, 4 and 6% (by weight) of AA in water. The studies were conducted at four temperatures (303.15–318.15 K with an interval of 5 K) and pressure 0.1 MPa with concentration of ZnSO4·7H2O in the solution ranging from 0.01 to 0.12 m. Various parameters like partial molar volume (ϕ v), apparent molar volume ( ϕ v o ) $({\phi }_{\text{v}}^{\text{o}})$ , Hepler’s constant ( ( d 2 ϕ v o / d T 2 ) p ) $({({d}^{2}{\phi }_{\text{v}}^{\text{o}}/d{T}^{2})}_{p})$ , partial molar expansibility ( ϕ E o ) $({\phi }_{\text{E}}^{\text{o}})$ and transfer volume ( Δ t r ϕ v o ) $({{\Delta}}_{tr}{\phi }_{\text{v}}^{\text{o}})$ have been evaluated from volumetric studies. The viscosity studies have yielded Jones-Dole parameters (A and B) and free energy of activation per mole for solvent ( Δ μ 1 0 ‡ ) $({\Delta}{\mu }_{1}^{0{\ddagger}})$ and solute ( Δ μ 2 0 ‡ ) $({\Delta}{\mu }_{2}^{0{\ddagger}})$ . The conductance data has been used to calculate molar conductance (Λm), limiting molar conductance ( Λ m o ) $({{\Lambda}}_{\text{m}}^{\text{o}})$ and Walden product ( Λ m o η o ) $({{\Lambda}}_{\text{m}}^{\text{o}}{\eta }_{\text{o}})$ . The results of these studies agree with each other and have concluded the structure breaker behavior of ZnSO4·7H2O in the solvent system containing AA and water.

Flow regimes, mixing and reaction yield of a mixture in an X-microreactor

In the present work, experimental flow visualizations and numerical simulations are carried out jointly to investigate how flow regimes affect the reaction yield in an X-microreactor. The X-microreactor is fed with an aqueous solution of ascorbic acid into one of the inlet channels and an aqueous solution of methylene blue and hydrochloric acid into the other which, upon reacting, produce a colorless reaction product that can be directly measured in experiments. Different kinetic constants are considered.At low Reynolds number, Re, the two reactant streams remain stratified in the mixing channels due to their different densities and mixing is promoted only by diffusion. By increasing the Reynolds number, the engulfment regime occurs, which is characterized by the presence of a single vortical structure in the confluence region and in the outlet channels, enhancing mixing thanks to convection. The reaction yield is studied both numerically and experimentally showing a remarkable agreement between the results. In the stratified regime, the reaction yield decreases with the Reynolds number due to a decrease in residence time. Instead, with the onset of the engulfment regime, the reaction yield starts to increase with Re because enhancement in the mixing degree between the streams overcomes the reduction of the residence time. However, due to the opposite behaviors of mixing efficiency and residence time with Re, the reaction yield does not monotonically increase with Reynolds number within the engulfment regime, but it reaches a maximum and then slightly decreases. The reaction yield obtained in the X-microreactor is significantly larger than that of a T-microreactor having the same cross-section geometry and operating in the same conditions.

Limiting apparent molar volumes, limiting apparent molar isentropic compressions, transfer parameters and transition state theory for ternary mixtures of Gly-Gly-Gly in aqueous solutions of ascorbic acid at temperatures between (298.15 and 318.15) K

Density, speed of sound, viscosity parameters were measured for glyclyl-glycyl-glycine in aqueous molal solutions of ascorbic acid were reported at condition of pressure (=0.1 MPa) and temperature (ranging 298.15–318.15) K. The results of thermophysical properties were obtained in the molality range (0.0499 to 0.3998) mol·kg−1 for glycyl-glycyl-glycine and of (0.1942, 0.3773, 0.5504, 0.7142) mol·kg−1 for ascorbic acid. The various thermophysical parameters like apparent molar volume, apparent molar isentropic compression, limiting apparent molar volumes, limiting apparent molar isentropic compression, empirical-interaction coefficients, transfer parameters (from volumetric and acoustic data), Falkenhagen coefficient, Jones-Dole coefficient, and dB/dT (first derivative of B-coefficient were computed with the help of experimental values. Also, the Gibbs free energy of activation of solvent and solute were calculated and explained with the help of transition state theory. The studied thermophysical parameters at different temperatures and molal concentrations were explained from the point of view of solute–solute and solute–solvent interactions and their structural effects.

Dibenzothiophene-S,S-dioxide-containing conjugated polymer with hydrogen evolution rate up to 147 mmol g−1 h−1

Molecular engineering in donor–acceptor conjugated polymers is currently one of the most successful and popular strategy to prepare high performance photocatalysts for hydrogen evolution. In this contribution, we have designed and synthesized two novel conjugated polymers with tailored donor–acceptor structures based on dibenzothiophene-S,S-dioxide and thiophene derivatives, which exhibited tunable band gaps and adjustable charge separation efficiencies. As a result, PDBTSO-T showed an outstanding hydrogen evolution rate (HER) of 1.47 mmol h−1 by DMF exfoliation under UV−vis region with Pt cocatalyst in ascorbic acid aqueous solution at 10 mg level, which is among the top performance for photocatalysis conversion reported so far. Very excitingly, when the photocatalysis tests were subjected to natural sunlight irradiation, an impressive HER of ~27 mL (107 mmol g−1 h−1) was achieved after 0.5 h of illumination (12:30 pm − 13:00 pm) on a consistently sunny day under identical reaction conditions.

Systematic HPLC/DAD/MSn study on the extraction efficiency of polyphenols from black goji: Citric and ascorbic acid as alternative acid components in the extraction mixture

BACKGROUND: The beneficial effects of the fruit of Lycium rhutenicum (black goji) have been linked to their polyphenolic profile. OBJECTIVE: Systematic examination of the extraction efficiency of polyphenols from cultivated black goji from Macedonia was carried out using 25 different solvent mixtures containing methanol, acetone or water combined with different acids (hydrochloric, acetic, citric and ascorbic acid). METHODS: An HPLC/DAD/MSn method was used for identification and quantification of phenolic acids, flavonoids, anthocyanins and also spermines and spermidines. RESULTS: The extraction solvent composition was found to have a significant effect on the yield of total as well as specific polyphenols. Pure methanol was found to be more efficient solvent for extraction of total phenolic compounds than pure water or acetone. Ascorbic acid in methanol (2%, m/v) was found to be the most efficient extraction solvent for total phenolic compounds. Aqueous solutions of citric and ascorbic acid gave the highest yield of phenolic acids, spermidines and flavonoids. The anthocyanin content in these extracts was somewhat lower in comparison with the one obtained with methanol/water/ascorbic acid (70 : 28 : 2). The qualitative analysis of the fruits cultivated in Macedonia showed similar polyphenolic pattern and anthocyanin content to the native plant growing in China. CONCLUSIONS: Citric and ascorbic acid can be used as alternative acid components in the extraction mixture.

A novel gold nanoparticle-based colorimetric assay for highly sensitive detection of ascorbic acid

In this study, a novel approach for colorimetric detection of ascorbic acid (AA) was proposed based on the peroxidase-like activity of gold nanoparticles, which were synthesized using Oldenlandia corymbosa leaves extract (OC-AuNPs). The OC-AuNPs synthesis was optimized at 0.5 mM Au3+, a reaction time of 20 min, and a temperature of 60 °C. The results showed that the biogenic OC-AuNPs presented as highly-efficient peroxidase mimics for catalyzing H2O2 to oxidize 3,3′,5,5′-tetramethylbenzidine forming a typical blue product with the characteristic absorption at 654 nm. The developed colorimetric method exhibited high sensitivity for AA with a detection limit of 0.26 μM in the linear range of 0 – 100 μM. The proposed assay can be serviced as a sensitive biosensor for the determination of AA in aqueous solutions due to its simple detection procedure, fast operation, and high sensitivity.

In Situ Assembly of Gold Nanoparticles in the Presence of Poly-DADMAC Resulting in Hierarchical and Highly Fractal Nanostructures

The presence of the polycationic macromolecule poly(diallyldimethylammonium chloride) (poly-DADMAC) has a strong effect on the shape and size of colloidal gold nanoparticles formed by the reduction of tetrachloroauric acid with ascorbic acid in aqueous solution. It slows down nanoparticle growth and supports the formation of nonspherical, partially highly fractal and hierarchical nanoparticle shapes. Four structural levels have been recognized from the near-spherical gold nanoparticles in the lower nanometer range over compact aggregates in the midnanometer range and flower and star-like particles in the submicron range up to larger filamentous aggregates. High-contrast scanning electron microscope (SEM) images show that single gold nanoparticles and clusters of them are connected by bundles of macromolecules in large aggregates. The investigation showed that a large spectrum of different nanoparticle shapes and sizes can be accessed by tuning the poly-DADMAC concentrations and their ratio to other reactants. The nanoassemblies with a very high specific surface area might be of interest for SERS and heterogeneous catalysis.

BIO STIMULANT ACTIVITY OF CHITOSAN DISSOLVED IN DIFFERENT ORGANIC ACIDS ON TOMATO PLANT

This study aims to evaluate and compare the stimulant capabilities of the foliar application of chitosan, dissolved in aqueous solutions of four organic acids (acetic acid, ascorbic acid, citric acid, and malic acid), on tomato (Solanum lycopersicum L.). A pot experiment was carried out under greenhouse conditions during the summer season. Morphological traits, photosynthetic pigments, ascorbic acid, total phenol, osmolytes, antioxidant enzyme activities (peroxidases, polyphenol oxidases, Superoxide dismutase, and catalase), and yield parameters were evaluated. The results indicated that chitosan treatments showed improvements in almost all aforementioned parameters, these responses were different according to the associated organic acid. Moreover, chitosan treatments, compared to control, significantly increase all the studied yield parameters in tomato plants, especially chitosan dissolved in an aqueous solution of malic acid and ascorbic acid that gave the most potent effect regarding the number of flower/ plant, the number of fruits, as well as the weight of fruits/ plant in comparison with plants treated with chitosan dissolved in an aqueous solution of citric acid, or acetic acid, respectively. Since it is a non-toxic, biocompatible, biodegradable, and available material in the global market, the foliar application of chitosan, especially that dissolved in aqueous solutions of ascorbic or malic acids, are recommended to be used as commercial applications under normal conditions (not stressed) as pre and after flowering biostimulants to improve tomato plant health and thus increasing the yield. The results can be extended to all the plants of the family Solanaceae after further investigations.

PRODUCTIVITY AND OIL QUALITY OF THYMUS VULGARIS L. UNDER GROWTH PROMOTERS AND SOILLESS CULTURE CONDITIONS

Thyme (Thymus vulgaris L.) belongs to the lamiaceae family. It is characterized by its medicinal and economic values. Thymus is grown worldwide for cosmetic and medical use. Plant bio-stimulants are classified as substances which have positive effects on growth and productivity of plants. Bio-stimulants are obtained naturally from various economically and environmentally viable sources. The current experiment aimed to investigate the response of thymus physical and chemical properties to the different types and concentrations of bio-stimulators under soil less culture conditions for two successive seasons 2019 and 2020. Thymus seedlings were planted in pots filled with mixed media of perlite: sand (1:1v/v). Plants were sprayed with aqueous solution of ascorbic acid (1 and 2g/l), aspartic acids (500 and 1000 ppm) and dry yest (2 and 4g/l) and combination of them compared with control. The herp was harvested in mid- July (First cutting) and first week of October (second cut). Growth and yield characters were measured. The essential oil percentage was determined and analyzed by GC in both cuts from the fresh herb. Results showed that, spraying of mixtures of ascorbic acid (2g/l), aspartic acids (1000 ppm) and yeast (4g/l)) significantly increased yield, total carbohydrates, total phenols, total pigments, essential oil percentage and yield as well as its NPK content characters and components of essential oil high contents of thymol, ? and ? –Pinene during both cuts and for both seasons. Economic evaluation was carried out by calculating with the highest return in the mixture treatment. It is clear that all treatments are economically feasible however, one can find that the maximum return or profit comes from mixture treatments where the benefit to cost ratio were 3.99 and 3.9 for Mix2 and Mix1 respectively.

Effects of Priming with Ascorbic Acid, L-Cystein and Triacontanol on Germination of Rapeseed (Brassica napusL.)

AbstractThe germination of seed batches of two rapeseed (Brassica napusL.) hybrids (‘Hybrirock’ and ‘Factor’) were investigated in response to priming in aqueous solutions of ascorbic acid (10 mM), L-cysteine (10 mM) and triacontanol (1 μM), respectively tap water (as control treatment). Investigations were focused on seed quality parameters, such as germination percentage, mean germination time, germination index, uniformity of germination, and seedling shoot and root growth. Germinated seeds were counted every 24 hours for a period of seven days, recording the final germination percentage (FGP), mean germination time (MGT), the coefficient of velocity of germination (CVG), germination rate index (GRI), germination index (GI), uncertanty (U), and synchrony (Z). In a separate trial fresh shoot- and root length, respectively the dry weight of the shoots and roots were also determined after a 14 day period. Germination tests were performed to examine the quality of seeds in response to different priming treatments. The results demonstrated that priming improved the germination parameters of seeds of both hybrids. Furthermore, the use of ascorbic acid, L-cysteine and triacontanol also enhanced seedling growth. The results may be used to rank seed lots by vigor, and decisions can be made regarding planting potential of each seed lot.