Salma Ali Al-Tamimi

Recently, dual-mode techniques have garnered considerable attention and have been shown to be effective approaches for biomedical analysis and environmental monitoring. A novel and simple dual-mode spectrophotometric and fluorometric probe based on lignin-derived carbon dots (LCDs) was developed to detect atorvastatin calcium (ATS) in a bulk powder and its commercial product. The synthesized LCDs exhibit exceptional fluorescence characteristics and are highly soluble in water while maintaining reasonable stability. The average particle size of the LCDs was 3.42 ± 1.03 nm. The characterization of the produced LCDs indicated a structure resembling graphene oxide with the presence of several functional groups. The developed LCDs show a good fluorescence quantum yield of 32.2%. The fluorescence of the LCDs is quenched by ATS at an emission wavelength of 315 nm after excitation at 275 nm through dynamic and static quenching mechanisms. The optimal reaction conditions for the dual-mode reaction were a pH of 9 and 0.05 mL of the LCDs, which were measured after 3 min at 30 °C by spectrophotometry, followed by 7 min at 20 °C by fluorometric methods. According to the spectrophotometric results, the response of ATS was linear in the range of 4.0–100.0 µg/mL, while according to the fluorometric results, the dynamic range was 3.0–50.0 µg/mL. The limits of detection (LODs) and the limits of quantification (LOQs) were 0.97 µg/mL and 2.95 µg/mL for the fluorometric method, respectively. The nanoprobe effectively analyzed ATS in medication samples and yielded good results.

The existing study pronounces two newly developed spectrofluorimetric probes for the assay of ambroxol hydrochloride in its authentic and commercial formulations using an aluminum chelating complex and a biogenically mediated and synthesized aluminum oxide nanoparticles (Al₂O₃NPs) from Lavandula spica flower extract. The first probe is based on the formation of an aluminum charge transfer complex. However, the second probe is based on the effect of the unique optical characteristics of Al₂O₃NPs in the enhancement of fluorescence detection. The biogenically synthesized Al₂O₃NPs were confirmed using various spectroscopic and microscopic investigations. The fluorescence detections in the two probes were measured at a λ_ex of 260 and 244 and a λ_em of 460 and 369 nm for the two suggested probes, respectively. The findings showed that the fluorescence intensity (FI) covered linear concentration ranges of 0.1–200 ng mL⁻¹ and 1.0–100 ng mL⁻¹ with a regression of ˃0.999 for AMH-Al₂O₃NPs-SDS and AMH-Al(NO₃)₃-SDS, respectively. The lower detection and quantification limits were evaluated and found to be 0.04 and 0.1 ng mL⁻¹ and 0.7 and 0.1 ng/mL⁻¹ for the abovementioned fluorescence probes, respectively. The two suggested probes were successfully applied for the assay of ambroxol hydrochloride (AMH) with excellent percentage recoveries of 99.65% and 99.85%, respectively. Excipients such as glycerol and benzoic acid used as additives in pharmaceutical preparations, several common cations, and amino acids, as well as sugars, were all found to have no interference with the approach.

This study describes Green synthesis of two metal oxide nanoparticles MnO₂NPs and CuONPs using the oat biomass. The electrocatalytic activity of the synthesized metal oxide nanoparticles was investigated by fabricating two modified sensors enriched with MnO₂NPs and CuONPs as a coated layer on the surface of the sensors and utilized to quantify antibacterial drugs cephalexin (CPX) and cefazolin (CFZ) in their commercial products and biosamples. The tested drugs were incorporated with the precipitating agents phosphomolybdic acid and phosphotungstic acid to form CPX-PM and CFZ-PT as electroactive materials, respectively. Conductivity enhancement of the fabricated modified sensors CPX-PM-MnO₂NPs and CFZ-PT-CuONPs was determined and the outcomes compared to the results obtained from the conventional types of the same sensors. Linear relationships were recorded between the sensory potentials of the enriched metal oxide nanoparticles in the ranges of 1.0 × 10^-8-1.0 × 10^-2 and 1.0 × 10^-10-1.0 × 10^-2 mol L^-1 with lower limits of detection 5.6 × 10^-9 and 5.7 × 10^-11 mol L^-1 for CPX-PM-MnO₂NPs and CFZ-PT-CuONPs with respect to 1.0 × 10^-6-1.0 × 10^-2 mol L^-1 of their conventional coated wire types. The fabricated sensors provide excellent sensitivity and selectivity towards the determination of CPX and CFZ in its commercial and biosamples. GRAPHICAL ABSTRACT

The adsorption of Ciprofloxacin (CPX) from aqueous solution by Pomegranate peels (POP) was investigated in a batch process. The influence of time (5–60 min) and CPX concentration (100–10,000 mg/L) on the adsorption ability of POP was studied. The POP was characterized by FTIR, scanning electron microscopy (SEM), and Zeta sizer. The kinetic of adsorption was analyzed by the pseudo-first-order and the pseudo-second-order kinetic equations using non-linear regression analysis. As well as non-linear regression analysis of Langmuir and Freundlich models were applied to specify the best non-linear curves, fitted to experimental data and estimate isotherm parameters. In order to assess the best-fit kinetic model or adsorption isotherm, three error analysis methods were used to evaluate the result of adsorption process, namely the sum of the squares of the errors (SSE), residual root mean square error (RMSE), and chi-square (χ2). On the basis of low three error analysis and high correlation (R²) of determination, it can be concluded that both the non-linear form of pseudo-second-order kinetic model and non-linear form of Langmuir are best suited to explain the adsorption of CPX onto POP. The maximum adsorption capacity for pomegranate peel as calculated by non-linear Langmuir curve was much higher than in previous work (999 mg/g) at natural pH (4–5) and 25 °C. The high adsorption capacity of POP makes them very low-cost and effective adsorbent materials for CPX from aqueous solution.

A simple, rapid and highly sensitive spectrofluorimetric method was developed for determination of gemifloxacin mesylate (GFX) in tablets. The method is based on measuring the native fluorescence of GFX in isopropanol at 400 nm after excitation at 272 nm. The fluorescence–concentration plot was rectilinear over the range of 0.01–0.50 µg/mL with a lower detection limit of 1.19 ng/mL and quantification limit of 3.6 ng/mL. The method was fully validated and successfully applied to the determination of GFX tablets with an average percentage recovery of 99.65 ± 0.532. The method was extended to the stability study of GFX. The drug was exposed to acidic, alkaline, oxidative and photolytic degradation according to International Conference on Harmonization guidelines. The rate of GFX degradation was found at its highest in acidic conditions, and in its lowest in the neutral one. However, it was stable under dry heat and photolytic degradation conditions. Copyright © 2013 John Wiley & Sons, Ltd.