Control of molecular and supramolecular properties is used to obtain a new advanced hybrid material based on Prussian blue nanoparticles (PB NPs). This hybrid material is obtained through a self-assembled Layer-by-Layer (LbL) approach combining the advantageous features of β-cyclodextrin (β-CD) polysaccharides, PB NPs and poly(allylamine hydrochloride) from electrostatic interaction between the deposited layers. Transmission electronic microscopy images suggested that PB NPs were protected by β-CD polysaccharides that prevent the aggregation phenomena. In addition, as confirmed by scanning electronic microscopy images, it was found that PB NPs are organized in microcubic supramolecular like structures via a mesoscale self-assembly process. Interestingly, the 3-bilayer {PAH/PB-CD} film exhibited a higher density of microcubic structures and a high electrochemical response with PB sites available for redox reactions at a supramolecular level. By utilizing fewer bilayers and consequently less material deposition, the formed {PAH/PB-CD} multilayer films of a tuneable conductivity can be expected to have interesting future applications for host-guest like dependent electrochemical biosensing designs.
Boron is an essential element for plants and fruits: its deficiency is known to be the cause of growth damages, like in form and color, whereas its excess can be toxic. The fundamental importance of boron to animals and humans has not been identified, although excess boron can seriously affect human health. Thus, boron determination is important, so numerous research works have determined the element through spectrophotometric methods, based on the formation of the boron-azomethine-H complex. However, the methods based on this principle that are proposed exhibit inconsistencies, because at pH 4 - 8, the wavelengths 400 - 420 nm and analysis time, vary significantly, namely from 10 to 45min, thus making the methodology unreliable. This work focused on the formation of the boron-azomethine-H complex using UV-Vis; also, an electrochemical method was designed to determine boron, which resulted fast, simple and efficient, due to construction of a working electrode that indicates boron, based on its surface modification with B-Cyclodextrin, B-CD, and azomethine-H, where the former acts as recognition agent for boron, thus enabling potentiometric detection.
The present work focuses on the use of the anionic surfactant sodium dodecyl sulphate, SDS, along with the differential pulse voltammetry, DPV, with a carbon paste electrode as modified by the surfactant and optimising the experimental conditions to improve the process of determination of DA in the presence of AA. It is relevant to add that the study was undertaken at acid pH values to avoid degradation of the solutions containing both the DA and the AA.Optimization of the experimental conditions permitted to obtain a calibration plot for the DA in the presence of the AA, having a 0.01 to 0.2 mM linear range and detection limit of 0.00821 mM
This work deals with the electrochemical study of Azometine-H by mean of cyclic voltammetry using a carbon paste electrode modified with multi-wall carbon nanotubes, MWCNT, and b-Cyclodextrin. The results obtained evidence that it possible to follow the electrochemical evolution of the azometin-H at pH 7.0 and that the use of an electrode modified with carbon nanotubes improved the electrochemical response, favoring the electron transfer and increasing the oxidation peak's current, as compared with a conventional carbon paste electrode. Further, it was found that the azometine-H displayed an adsorption process associated to the interaction between the compound under study and the b-ciclodextrin.
The present research work presents the results concerning the effect of the modifications done on a carbon paste electrode, CPE, through using supramolecular systems, such as: multiwalled carbon nanotubes, MWCNT, b-cyclodextrin, b-CD, and a new conducting polymer electrochemically formed on the CPE, via polymerization of the b-CD, polyb-CD. Such systems induced increases in the heterogeneous reaction constants k0 and on the ratio jap/jcp, and a decrease in the Ep difference, as compared to the unmodified CPE. Also, the determination of dopamine, DA, was carried out from a commercial pharmaceutical product in the presence of ascorbic acid, AA, with the CPE/poly-b-CD and the CPE/MWCNT/b-CD, because these gave the best analytical parameters for the quantification of DA, giving satisfactory results.
Objective: To develop and validate an easy, rapid, sensitive and selective high-performance liquid chromatography with photodiode diode-array (HPLC-PDA) detection method for quantification of paracetamol and to demonstrate its application in a pharmacokinetic–pharmacodynamic study with arthritic rats.Methods: Paracetamol was separated from plasma samples (50-100 µl) by a single protein precipitation step, prior to HPLC-PDA detection. The separation was performed on a Knauer Eurospher II, C18 column 5 µm, 150 × 4.6 mm. The mobile phase comprised a mixture of water: methanol (75:25) and the flow rate was 1.1 ml/min. The detection wavelength was set at 245 nm. All analyses were carried out at room temperature (25 °C). Pharmacodynamics data were obtained with a gout-type pain model in rats.Results: The method was linear within a range of 0.2-200 µg/ml (R2≥0.99). The intra-day and inter-day precision and accuracy expressed as coefficient of variation and relative error, respectively were below 10%. The lower limit of quantification was 0.2 µg/ml. Plasma samples were stable at least for 5 w at ‒20° C.Conclusion: The validated method is sensitive, precise, accurate and specific as other more complex high-performance liquid chromatographic methods coupled to mass spectrometry (HPLC-MS), using small plasma samples (50-100 µl) and with a short time analysis (<5 min). The method was successfully applied to a pharmacokinetic-pharmacodynamic study of paracetamol in arthritic rats.
The manuscript Tenoxicam is a non-steroidal pharmaceutical that acts as anti-inflamatory, anti-pyretic and analgesic. It is amply used to treat rheumatic affections, from which it stems the importance to maintain its chemical stability through formation of an inclusion complex with β-ciclodextrin, β-CD. This work presents the results concerning the cyclic voltammetry studies carried out on tenoxicam at different pH in the presence of β-CD in aqueous media, and the analysis of the acid-base species which intervene as part of the Tenoxicam-β-CD interactions.
This work shows the interaction of dopamine (DA) and ascorbic acid (AA) with β-cyclodextrin (βCD), by means of UV-VIS spectrophotomety and cyclic voltammetry, to demonstrate the formation of inclusion complexes of the species and to determine the values of the formation constants in aqueous media at pH 3.0, also through both methods. For the ascorbic acid-βCD complex (H 2 AA-βCD) a value of 3.5082 ± 0.0445 was found, while for the dopamine complex DA-βCD (H 3 DA+βCD) it was 3.772 ± 01631. With such values theoretical absorption spectra were generated which fitted quite well to the experimental ones, thus indicating clearly that the constants are reliable.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.