Sami El Deeb - Academia.edu (original) (raw)

Papers by Sami El Deeb

SCIENTIA SINICA Chimica, 2016

Phytohormones, being a series of trace organic compounds synthesized in plants and playing import... more Phytohormones, being a series of trace organic compounds synthesized in plants and playing important roles in plant growth at their low concentration, have been extensively studied in recent years. The ultrasensitive and in-situ detection of phytohormones remains an important scientific field in the plant research. In many existed detection methods, the electrochemical method has been acclaimed as a result of its excellent performance of high sensitivity and dynamic monitoring. In this review, we briefly introduce the recent advances in electrochemical sensing of phytohormones, including electrochemical biosensing, direct electrochemical sensing, photoelectronchemical sensing, and molecularly imprinted electrochemical sensing. Finally, the trends in electrochemical sensing of phytohormones are discussed.

Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2010

ABSTRACT Formation of charge transfer complexes of methyl viologen, MV, and hosts (1–3) in ethano... more ABSTRACT Formation of charge transfer complexes of methyl viologen, MV, and hosts (1–3) in ethanol were studied using UV–visible spectrophotometry. The stability constants and the thermodynamic parameters of the resulting 1:2 (MV:host ratio) complexes were determined. All charge transfer complexes formed were enthalpy destabilized, but entropy stabilized. The effect of donor atoms, their orientation, the substituents, flexibility and the cavity size of the crown ethers on the formation constants and thermodynamic parameters will be discussed. KeywordsCharge transfer complexes–Methyl viologen–Stability constants–Crown ethers

Analytical and Bioanalytical Chemistry, 2010

Capillary electrophoresis based on the principles of frontal analysis (CE-FA) was used to charact... more Capillary electrophoresis based on the principles of frontal analysis (CE-FA) was used to characterize the binding of flavonoids to human serum albumin (HSA) at near-physiological conditions: 67 mM phosphate buffer (pH 7.4), temperature 36.5 degrees C. The studied flavonoids (flavone, rutin, quercitrin) displayed moderate affinities toward the human serum albumin with binding constants in the range 10(3)-10(4) M(-1). The binding of the flavonoids to the protein noticeably depended on their lipophilicity and decreased in the case of glycosylation. The corresponding thermodynamic parameters characterized the acting forces between the HSA and flavonoids as mainly hydrophobic forces and electrostatic interactions. Based on the results of the displacement experiments, the binding of the flavonoids took place at site I of the HSA molecule. The results demonstrated by CE-FA were similar to those obtained by fluorescence spectroscopy. The developed method proved to be a reliable alternative to conventional methods, providing a lot of useful parameters for characterization of ligand-protein interactions.

Analytical and Bioanalytical Chemistry, 2006

Because variability exists within populations of cells, single-cell analysis has become increasin... more Because variability exists within populations of cells, single-cell analysis has become increasingly important for probing complex cellular environments. Capillary electrophoresis (CE) is an excellent technique for identifying and quantifying the contents of single cells owing to its small volume requirements and fast, efficient separations with highly sensitive detection. Recent progress in both whole-cell and subcellular sampling has allowed researchers to study cellular function in the areas of neuroscience, oncology, enzymology, immunology, and gene expression.

Archiv Der Pharmazie, Apr 3, 2023

The endemicity of the pandemic coronavirus disease 2019 (COVID‐19) infection proved to be transit... more The endemicity of the pandemic coronavirus disease 2019 (COVID‐19) infection proved to be transitional only. Spikes are forming again in 2023, and high expectations are returning for reinfections and viral mutations. Molnupiravir (MOL) has been approved as an oral antiviral drug for the treatment of the COVID‐19 causative virion. Therefore, the development of an ultrasensitive, instantaneous, and cost‐effective method for the quantification of MOL in real plasma samples and formulated dosage form are mandatory. The proposed approach is based on the synthesis of a MOL metal‐chelation product. MOL as a ligand was chelated with 1.0 mM zinc(II) in an acetate buffer (pH 5.3). After illumination at 340 nm, the intensity of the MOL fluorescence measured at 386 nm was increased by about 10‐fold. The linearity range was found to be from 60.0 to 800.0 ng mL−1 with limit of quantitation (LOQ) of 28.6 ng mL−1. Two methods were utilized for measuring the greenness of the proposed method (Green Analytical Procedure Index [GAPI] and analytical greenness metric [AGREE] methods), with results equal to 0.8. The binding stoichiometry of MOL with the zinc(II) ion was found to be 2:1. All the experimental parameters were optimized and validated using International Conference on Harmonization (ICH) and United States Food and Drug Administration (US‐FDA) recommendations. Furthermore, the fluorescent probes were successfully utilized in real human plasma with high percentages of recovery (95.6%–97.1%) without any matrix interferences. The mechanism of fluorescent complex formation was confirmed using 1H NMR in the presence and absence of Zn(II). The method was further utilized for testing content uniformity of MOL in its marketed capsule dosage forms.

Microchemical Journal, Sep 1, 2023

Journal of Chromatography A, Sep 1, 2023

Methods and Applications in Fluorescence, Jul 28, 2022

The in vitro panel of technologies to address biomolecular interactions are in play, however micr... more The in vitro panel of technologies to address biomolecular interactions are in play, however microscale thermophoresis is continuously increasing in use to represent a key player in this arena. This review highlights the usefulness of microscale thermophoresis in the determination of molecular and biomolecular affinity interactions. This work reviews the literature from January 2016 to January 2022 about microscale thermophoresis. It gives a summarized overview about both the state-of the art and the development in the field of microscale thermophoresis. The principle of microscale thermophoresis is also described supported with self-created illustrations. Moreover, some recent advances are mentioned that showing application of the technique in investigating biomolecular interactions in different fields. Finally, advantages as well as drawbacks of the technique in comparison with other competing techniques are summarized.

Microchemical Journal, Jun 1, 2021

Biologics have more complex production processes compared to small-molecule drugs. They may even ... more Biologics have more complex production processes compared to small-molecule drugs. They may even prove labile when drifting from batch-to-batch or in different production locations. The development of new similar biological product was regulated early to face the relevant challenges of this industry. As a result, since 2006 biosimilars were introduced to biotechnology arena with a massive competition in pharmaceutical industry. In this review, the aspects related to similarity testing of biosimilars to the original biological products are discussed involving manufacturing challenges to ensure the quality, safety, and efficacy of these products to the patient health. Immunogenicity studies are highlighted as an important part of the safety assessments. Additionally, several analytical methods that are usually used to evaluate biosimilars in comparison to their reference biologic are summarized and categorized in terms of the intended physicochemical and biological characterization. On the other hand, the international efforts of several regulatory agencies including the European Medicines Agency, World Health Organization and United States Food and Drug Administration for biosimilar development are discussed according to updated revised guidelines.

Nanomaterials, Apr 26, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

This study examined the possibilities of using capillary electrophoresis-frontal analysis (CE-FA)... more This study examined the possibilities of using capillary electrophoresis-frontal analysis (CE-FA) for the characterization of drug-metal binding parameters such as formation constant (Kf) and number of binding sites. Deferiprone and iron in the Fe(III) form were selected as model system. Apparent Kf values were obtained using nonlinear regression. The results provide a more quantitative picture of how this drug binds with metal and illustrate how CE FA can be used to examine drug metal interactions.

RSC Advances, 2022

The COVID-19 pandemic has encouraged the search for novel antiviral medications. Recently, molnup... more The COVID-19 pandemic has encouraged the search for novel antiviral medications. Recently, molnupiravir (MOL) has been approved as an oral antiviral to manage COVID-19. Thus, the development of sensitive and cost-effective methods for quantification of MOL in real plasma samples (pharmacokinetic) and pharmaceutical tablets is required. Herein, we present the fabrication of novel fluorescent polyamine quantum dots (PA@CQDs) fabricated from apricots using one step synthesis for analysis of MOL. The relative fluorescence intensity (RFI) of the synthesized quantum dots was influentially quenched by the addition of molnupiraivr. The linear range was found to be between 2-70 ng mL À1 with lower limit of quantitation (LOQ) equal to 1.61 ng mL À1. The fluorescent probe was successfully utilized in a pharmacokinetic study of MOL with maximum plasma concentration (C max) 920.2 AE 6.12 ng mL À1 without any matrix interference. The sensitivity and selectivity of the presented method allow its application in clinical laboratories.

Journal of Pharmaceutical and Biomedical Analysis, 2007

Methods developed on conventional particle-packed C18 columns for pilocarpine, propranolol, glibe... more Methods developed on conventional particle-packed C18 columns for pilocarpine, propranolol, glibenclamide, glimepiride, insulin and their respective degradation products or related compounds were transferred from the conventional Superspher 100RP-18e column to Chromolith Performance RP-18e columns. All transfers were successful applying the same chromatographic conditions, except for insulin where the acetonitrile content of the mobile phase was reduced by 0.5%. The intraday and interday precisions for both retention time and peak area were evaluated over a wide concentration range. Results were found to be equal, or slightly better on Chromolith Performance with RSD%<1.1% in all cases. Monolithic batch to batch repeatability of both retention time and peak area, compared for monolithic columns from different batches gave an RSD% of less than 1.3%. The separation of each drug and its related products was investigated on monolithic columns at flow rates from 1 to 9 ml/min, and superior resolution was always obtained using monolithic over conventional columns at the same flow rate. A total of seven monolithic columns from four different batches were used in this study.

Electrophoresis, 2000

... Rosanne M. Guijt-van Duijn,; Johannes Frank,; Gijs WK van Dedem,; Erik Baltussen. Article fir... more ... Rosanne M. Guijt-van Duijn,; Johannes Frank,; Gijs WK van Dedem,; Erik Baltussen. Article first published online: 13 DEC 2000. DOI: 10.1002/1522-2683(200012)21:18<3905::AID-ELPS3905> 3.0.CO;2-4. Copyright © 2000 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. ...

Water

A comparison of the growth performance of Penaeus vannamei was ascertained by supplementing the p... more A comparison of the growth performance of Penaeus vannamei was ascertained by supplementing the potential probiotics isolated from a biofloc system incorporated through feed. Post-larvae shrimp (0.045 ± 0.005 g) were stocked at a density of 500/m3 in FRP tanks (500 L) in triplicates for a period of 60 days. A total of 40 bacterial strains were isolated from previous biofloc culture trials and tested for their antimicrobial activity against the pathogen Vibrio parahaemolyticus. Among these, Bacillus megaterium, Exiguobacterium profundum, Pseudomonas balearica, and Pseudomonas stutzeri showed higher antimicrobial activity. The treatment groups included clear water with no probiotics (CW), clear water + isolated probiotic (CW + IP), biofloc alone (BFT), and biofloc + isolated probiotic (BFT + IP), in triplicates. Distillery spent wash was used as a carbon source for biofloc development and maintenance. A probiotic concentration of 1 × 109 cfu/g was supplemented throughout the trial. Th...

Molecules

Plaque psoriasis is a common, long-lasting illness that affects the immune system and causes sign... more Plaque psoriasis is a common, long-lasting illness that affects the immune system and causes significant negative impacts on a patient’s physical health, well-being, and ability to work effectively. Deucravacitinib (DEU) is the first oral medication used in the treatment of plaque psoriasis, a chronic skin condition that causes red, scaly patches on the skin. DEU is a type of medication called an oral Janus kinase (JAK) inhibitor, which works by blocking specific enzymes that play a role in the inflammation and immune response associated with psoriasis. Therefore, a quick, easy, novel, reliable, sensitive, and straightforward liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach was used to analyze DEU in plasma samples. The LC-MS/MS method for the determination of DEU in human plasma was based on using trimethoprim as an internal standard (IS). The separation of DEU and IS was carried out via liquid–liquid extraction (LLE). The extract was then subjected to the chromat...

Analytical and Bioanalytical Chemistry

Copper (Cu) plays a role in maintaining healthy nerve cells and the immune system. Osteoporosis i... more Copper (Cu) plays a role in maintaining healthy nerve cells and the immune system. Osteoporosis is a high-risk factor for Cu deficiency. In the proposed research, unique green, fluorescent cysteine-doped MnO2 quantum dots (Cys@MnO2 QDs) were synthesized and assessed for the determination of Cu in different food and hair samples. The developed quantum dots were synthesized with the help of cysteine using a straightforward ultrasonic approach to create 3D fluorescent Cys@MnO2 QDs. The resulting QDs’ morphological and optical characteristics were carefully characterized. By adding Cu ions, the intensity of fluorescence for the produced Cys@MnO2 QDs was found to be dramatically reduced. Additionally, the applicability of Cys@MnO2 QDs as a new luminous nanoprobe was found to be strengthened by the quenching effect grounded on the Cu–S bonding. The concentrations of Cu2+ ions were estimated within the range of 0.06 to 7.00 µg mL−1, with limit of quantitation equal to 33.33 ng mL−1 and det...