Search

Celecoxib (CEL) serves as a selective inhibitor of cyclooxygenase-2 (COX-2) used for treating conditions like rheumatoid arthritis, osteoarthritis, acute pain, and inflammation. However, its limited solubility and slow dissolution significantly restrict its wider application. This research focused on exploring eutectic mixture of celecoxib with maleic acid to enhance physico-chemical properties of the anti-inflammatory agent. The binary mixtures of celecoxib-maleic acid were prepared over the entire composition range, using the liquid-assisted grinding technique and characterized through various analysis, including differential scanning calorimetry, powder X-ray diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy. In the DSC thermograms of the binary mixtures, a eutectic reaction was observed at 108.46°C. The analysis of the phase diagram of CXB-MA binary mixtures indicated a eutectic composition at approximately 0.35 molar fraction of celecoxib. Additionally, PXRD, FTIR provided the confirmation of the eutectic mixture formation, indicated the absence of molecular interactions in the solid state. [ABSTRACT FROM AUTHOR]

Ascorbic acid is known for its reductive properties. It is used on a wide scale as antioxidant in foods and drinks, it is also important for therapeutic purposes and biological [...], Deposited cobalt microparticales (Co-MPs) film onto the platinum disk electrode has been successfully used as a new amperometric sensor for the determination of ascorbic acid (AA). AA is detected by surface catalyzed oxidation involving cobalt(III) oxyhydroxides in alkaline solution. The Co-MPs/Pt electrode exhibits a high electrocatalytic activity toward the AA oxidation. The diffusion coefficient of AA (6.09 [10.sup.5] [cm.sup.2]/s) and the catalytic rate constant ([k.sub.cat] = 6.27 x [10.sup.3] [M.sup.-1][s.sup.-1]) have been determined using electrochemical approaches. The amperometric response of the modified electrode is linear against the AA concentration in the range (0.01-0.48 mM). The sensor displays the best activity with a high response signal, a good sensitivity of 74.3 [micro]A/mM, a low detection limit of 2.5 [micro]M (signal/noise = 3) and a fast response time ( Keywords: cobalt microparticles, electrocatalytic activity, ascorbic acid oxidation, amperometric detection

Novel green-emitting phosphors K2Zn1 − xP2O7: x mol% Mn2+ have been successfully prepared using classical solid-state reaction method in air atmosphere, doped by different Mn2+ ion contents, namely x = 0.5, 1, 1.25 and 1.5 mol%. The samples were characterized by the thermogravimetric (ATD/ATG/DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), steady and time-resolved photoluminescence techniques. It was found that all K2Zn1 − xP2O7: x mol% Mn2+ samples crystallize in the tetragonal phase with P42/mnm space group. Upon 425 nm excitation, K2ZnP2O7: Mn2+ exhibits an intense broad green asymmetric emission band peaking at 520 nm, owing to the 4T1→6A1(6 S) transition of Mn2+ ion in K2ZnP2O7. In addition, it is suggested that Mn2+ ions occupy more than one symmetry site in the host K2ZnP2O7. The optimal Mn2+ ion concentration in K2ZnP2O7:Mn2+ phosphor is 1 mol % and with the lifetime 9.81 ms. [ABSTRACT FROM AUTHOR]

Here, we report the synthesis and study of new orange‐red (OR) colour‐emitting phosphors Na2ZnP2O7:xTb3+ (x = 1, 1.25, 1.5, and 1.75 mol%) using a conventional solid‐state reaction. The sample crystallographic structures and their room temperature photoluminescence properties were measured using X‐ray powder diffraction, excitation and emission spectra, as well as emission decay curves. X‐ray diffraction analysis showed an isostructural tetragonal structure for all the doped materials with no impurities. Several colour emissions corresponding to 5D4→7F6 (blue), 5D4→7F5 (green), 5D4→7F4 (orange) and 5D4→7F3,2,0 (red) intraconfigurational transitions were observed and investigated. These colours were dominated by the OR colours. 5D4 energy level lifetime was independent of Tb3+ concentration. Various radiative and luminescence parameters, such as experimental branching ratio, radiative decay rate, and luminescence quantum efficiencies, were calculated and discussed. Chromaticity diagram calculations illustrated an orange emission for all the studied materials. [ABSTRACT FROM AUTHOR]

A sodium dodecylsulfate‐doped polypyrrole (SDS‐PPy) film was elaborated on glassy carbon electrode (GCE) by an electrodeposition method in phosphate buffer solution (pH 2.0) containing pyrrole (Py) and sodium dodecyl sulfate (SDS). SDS‐PPy/GCE was used for the construction of sensor, which showed excellent electrochemical response for the detection of ondansetron (OND) compared to conventional PPy. The application of the square wave (SW), with the adsorptive accumulation, indicates a maximum response at 1.33 V in H2SO4 (0.5 M). The influence of experimental parameters on determination of OND is discussed. The adsorptive stripping technique showed to be more sensitive, giving responses twice as big as those of non‐accumulated OND. The substantial improvement of response permits the development of an electroanalytical technique with a linear concentration in the range (1.0–80 μM), low detection (0.09 μM), and quantification limits (0.3 μM), and acceptable relative standard deviations of repeatability (0.59 %), and reproducibility (1.51 %). Consequently, this electrode is promising candidate for an accurate electroanalytical determination of OND in pharmaceutical samples with high sensitivity and selectivity, good accuracy and precision. The electrooxidation of OND at SDS‐PPy/GCE at various temperatures were studied by cyclic voltammetry to evaluate both the kinetic (ks and Ea) and thermodynamic (ΔG*, ΔH* and ΔS*) parameters. [ABSTRACT FROM AUTHOR]

In the present study, β-cyclodextrin-grafted chitosan nanoparticles (β-CDg- CS NPs) were prepared using a new ionic gelation strategy involving a synergistic effect of NaCl (150 mmol/L), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES, 10 mmol/L), and water bath sonication. This new strategy afforded smaller and more monodisperse β-CD-g-CS NPs vs. the classical ionic gelation method. New HA/β-CD-g-CS NPs were also prepared using the above-mentioned strategy by adding hyaluronic acid (HA) to the β-CD-g-CS copolymer at different weight ratios until the ZP values conversion. The best result was obtained with the weight ratio of w(HA):w(β-CD-g-CS) = 2:1 and furnished new spherical and smooth HA/β-CD-g-CS NPs. Furthermore, the stability of β- CD-g-CS NPs and HA/β-CD-g-CS NPs at 4°C in physiological medium (pH 7.4) was compared for 3 weeks period and showed that HA/β-CD-g-CS NPs were more stable all maintaining their monodispersity and high negative ZP values compared to β-CD-g-CS NPs. Finally, preliminary study of HA/β-CD-g-CS NPs as carrier for the controlled release of the anticancer drug doxorubicin was investigated. These new HA/β-CD-g-CS NPs can potentially be used as drug delivery and targeting systems for cancer treatment. [ABSTRACT FROM AUTHOR]