Hydrogen bonding recognition and colorimetric detection of isoprenaline using 2-amino-5-mercapto-1,3,4-thiadiazol functionalized gold nanoparticles

A near-infrared plasmonic biosensor for detection of morphine and codeine in biological samples based on the end-to-end assembly of modified gold nanorods

The analytical determination of opiates in biological samples is a critical mission and remains a challenge for almost all judicial and clinical drug testing panels due to their high abuse potential. Based on the high sensitivity of the longitudinal surface plasmon resonance (LSPR) peak of gold nanorods (AuNRs), we successfully developed a novel and simple refractive index sensing platform for detection of morphine (MOR) and codeine (COD) by means of 2-amino-5-mercapto-1,3,4-thiadiazole functionalized gold nanorods (AMTD-AuNRs) in aqueous solution, which is, to the best of our knowledge, the first report on the assay of MOR and COD using AuNRs. AMTD molecules strongly anchor onto the tips of AuNRs via the mercapto group and subsequent hydrogen-bonding interactions between AMTD and the analytes induced end-to-end chain assembly of AuNRs and a consequent decrease of the LSPR absorption band at 850 nm along with a bathochromic shift and emergence of a new hybridized plasmon mode at 1050 nm which was characterized using a Vis-NIR spectrophotometer. After systematic optimization, the absorbance ratio (A1050/A850) was proportional to the concentration of MOR in the ranges of 0.08-5 μM and 0.2-8 μM for COD without any significant effect from possible interferents. Furthermore, detection limits of 40 and 62 nM were achieved for MOR and COD, respectively, which are much lower than the cut-off level of 2000 ng mL-1 for opiates in urine samples set by the Substance and Abuse Mental Health Services Administration (SAMHSA). Eventually, as proof-of-applicability, human urine and blood serum samples spiked with MOR and COD were analyzed and excellent recoveries ranging from 94.4 to 108.9% were obtained, demonstrating the successful applicability of the designed refractive index probe in real biological specimens.

Electrochemical sensors for β-adrenoceptor agonist isoprenaline analysis in human urine and serum samples using manganese cobalt oxide-modified glassy carbon electrode

Schematic illustration for the synthesis of the MCO nanosphere and modification with GCE towards the electrochemical determination of isoprenaline.

Spectroelectrochemical Determination of Isoprenaline in a Pharmaceutical Sample

UV/Vis absorption spectroelectrochemistry (SEC) is a multi-response technique that has been commonly used for the characterization of materials and the study of reaction mechanisms. However, it has been scarcely used for quantitative purposes. SEC allows us to obtain two analytical signals simultaneously, yielding a dual sensor in just one experiment. In the last years, our group has developed new devices useful for analysis. In this work, a SEC device in parallel configuration, based on optical fibers fixed on screen-printed electrodes, was used to determine isoprenaline in a commercial drug, using both, the electrochemical and the spectroscopic signals. In this commercial drug, isoprenaline is accompanied in solution by other compounds. Among them is sodium metabisulfite, an antioxidant that strongly interferes in the isoprenaline determination. A simple pretreatment of the drug sample by bubbling wet-air allows us to avoid the interference of metabisulfite. Here, we demonstrate again the capabilities of UV/Vis absorption SEC as double sensor for analysis and we propose a simple pretreatment to remove interfering compounds.

Inhibition effects of isoproterenol, chlorpromazine, carbamazepine, tamoxifen drugs on glutathione S-transferase, cholinesterases enzymes and molecular docking studies

Nowadays, inhibition of acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and glutathione S-transferases (GSTs) have been a very crucial issue for pharmacological treatments of several disasters. Herein, we investigated inhibition effects of Tamoxifen (TAM), Isoprenaline (ISO), Chlorpromazines (CPZ) and Carbamazepine (CBZ) on GST, AChE, BChE and then molecular structures and active sides of the tested drugs by molecular docking process. The enzyme activity results showed that nearly the whole tested drugs inhibited GST, BChE, AChE efficiently. Chlorpromazine was found to be the best inhibitor for the GST enzyme and the Ki value of this drug was found to be 42.83 ± 8.52 nM. Besides, Isoproterenol drug with the Ki value of 51.80 ± 9.44 nM was found to be the most effective inhibitor on the AChE enzyme. Molecular docking studies showed that the receptor-binding sites of GST, AChE, and BChE were found to 1.069, 1.090, and 1.15 of Sitecore and 0.992, 1.113, and 1.217 of Dscore, respectively. The method was validated by doing validation studies and these validations revealed that re-docked ligands located a very closed position with co-crystallized ligand into the active site for all receptors. Calculation studies for determining the possible enzyme inhibition mechanism with the used drugs revealed that amino and aromatic ring in the structure of the drugs used are effective in inhibition reactions.Communicated by Ramaswamy H. Sarma.

Design and optimization of a luminescent Samarium complex of isoprenaline: A chemometric approach based on Factorial design and Box-Behnken response surface methodology

A chemometrically optimized procedure has been developed for the determination of isoprenaline (ISO) in the parent substance as well as in its respective pharmaceutical preparation. It is worth mentioning that although spectroscopic determination of Isoprenaline metal complexes has been described in literature, yet, no methods for the quantification of Isoprenaline with Samarium nor any other lanthanide metal have been reported. Fractional factorial design (FFD) was implemented in the initial screening procedure of the four designated factors, namely, reaction time (RT), metal volume (MV), pH and temperature (T) followed by Response Surface Methodology (RSM) optimization tool performed by the aid of Box Behnken design (BBD).The proposed techniques are based on a multivariate approach where a complexation reaction between Isoprenaline (ISO) and Samarium III (Sm³⁺) metal was exploited for the first time to synthesize novel fluorescence and absorbance probes of ISO-Sm. Maximum fluorescence intensity (Y1) as well as maximum absorbance (Y2) of the produced complex were attained at λ_ex/λ_em = 315/450 and λ 295 nm for spectrofluorimetric and spectrophotometric determinations, respectively, against blank solutions. Using assessment quality tools such as, Pareto charts, normal probability plots and statistical analysis of variance testing (ANOVA), significant factors were successfully indicated (p < 0.05). Furthermore, the proposed methods verified specificity and accuracy for the determination of Isoprenaline in its pure and pharmaceutical preparation using spectrofluorimetric (Technique A) and spectrophotometric (Technique B) techniques, respectively. Linearity was obtained in the range of (0.02-0.50 μg/mL) and (2-12 μg/mL) upon employing both techniques A and B, respectively. Furthermore, limit of detection (LOD) and limit of quantification (LOQ), were found to be 5.1877 ∗ 10^-3 μg/mL, 0.01572 μg/mL and 0.5593 μg/mL, 1.6949 μg/mL, upon employing techniques A and B, respectively. Standard addition method was applied for both techniques. The analysis was successfully applied to the assay of pure powder and pharmaceutical dosage forms after which the corresponding mean recoveries were computed and were found to be in the range of 99.546%-100.257% (Technique A) and 99.872%-99.887% (Technique B) with RSD (<1).