ORCID Profile
0000-0002-1533-4818
Current Organisation
University Of Strathclyde
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Publisher: SPIE
Date: 05-10-2023
DOI: 10.1117/12.2675805
Publisher: Oxford University Press (OUP)
Date: 03-2017
Abstract: Two specific, sensitive, and precise stability-indicating chromatographic methods were developed, optimized, and validated for the determination of Azintamide (AZ) in the presence of its degradation product. The first method was TLC combined with the densitometric determination of the separated bands. Separation was achieved using silica gel 60 F254 TLC plates and chloroform–acetone–glacial acetic acid (7.5 + 2.1 + 0.4, v/v/v) as the developing system. Good correlations were obtained between the integrated peak area of the studied drug and its corresponding concentrations in the linearity range. The second method used HPLC with UV diode-array detection, in which the proposed method was applied for the quantitative determination of AZ in the presence of its acidic degradation product and the quantitative determination of the acid-induced degradation product of AZ (AZ Deg) using pentoxifylline as the internal standard. The proposed components were separated on a reversed-phase C18 analytical column using acetonitrile–water (50 + 50, v/v). The flow rate was maintained at 0.55 mL/min and the detection wavelength was 260 nm. Linear regressions were obtained in the range of 1–30 and 0.3–16 μg/mL for AZ and AZ Deg, respectively. Different parameters affecting the suggested methods were optimized for maximum separation of the cited components. The suggested methods were validated in compliance with the International Conference on Harmonization guidelines and successfully applied for the determination of AZ in its pure powder form and in its pharmaceutical formulation. Both methods were also statistically compared with the reported method with no significant difference in performance observed.
Publisher: Elsevier BV
Date: 2022
Publisher: The Electrochemical Society
Date: 04-2020
Publisher: OMICS Publishing Group
Date: 2011
Publisher: WORLD SCIENTIFIC
Date: 27-09-2023
Publisher: Elsevier BV
Date: 11-2018
DOI: 10.1016/J.TALANTA.2018.07.045
Abstract: A label free electrochemical detection method for the rapid detection of recombinant human erythropoietin (rhuEPO) has been developed. In this method, we modified the rhuEPO structure for its direct sensing without using a complex signal lification strategy. The protein was selectively extracted from blood plasma s le using target-specific magnetic beads. After releasing rhuEPO from the magnetic beads, its disulfide bonds were electrochemically reduced and the protein was spontaneously assembled onto a nanostructured gold electrode via Au-S bonds formation. For electrochemical quantification, the reduced protein was desorbed from the electrode surface using differential pulse voltammetry (DPV). The desorption current was proportional to the concentration of rhuEPO in the range 1-1000 p.M. By cross-validating against ELISA, we found a 104.85 ± 3.35% agreement between the results obtained using the electrochemical biosensor and ELISA. Therefore the developed method has a strong potential for the sensitive detection of rhuEPO doping in sports as well as its rapid screening and pathology labs.
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.BIOS.2017.01.032
Abstract: A highly sensitive nanosensing method for the combined selective capture and SERS detection of Microcystin-LR (MC-LR) in blood plasma has been developed. The new method utilizes gold coated magnetic nanoparticles that are functionalized with anti MC-LR antibody Fab' fragments for the selective capture of MC-LR from aqueous media and blood plasma. Using an oriented immobilization approach, the Fab' fragments are covalently attached to gold surface to form a monolayer with high capture efficiency towards the toxin. After the selective capture, the purified MC-LR molecules were released from the extractor nanoparticles within 5min by manipulating the pH environment of the nanoparticles. The regenerated extractor nanoparticles maintained their capture efficiency and, therefore, were re-used to capture of MC-LR from successive s les. The released purified toxin was screened within 10min on gold coated silicon nanopillars and a new paper-based SERS substrate by handheld Raman spectrometer. The SERS enhancement factors of the nanopillars and the new paper-based substrate were 2.5×10
Publisher: Informa UK Limited
Date: 21-10-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2AN00703G
Abstract: SERS for antibiotic resistance diagnosis.
Publisher: Elsevier BV
Date: 2019
Abstract: The molecular structure of many proteins contains disulfide bonds between their cysteine residues. In this work we demonstrate the utilization of the disulfide bond structure of proteins for their label-free determination by surface-enhanced Raman spectroscopy (SERS). The new approach for label-free SERS detection of proteins is demonstrated for human insulin. The protein was selectively extracted from spiked plasma s les using target-specific functionalized nanomaterial. Enzyme-linked immune assay (ELISA) was used to detect insulin in the blood plasma and cross-validate the SERS method. The disulfide bonds in the molecular structure of the protein were chemically reduced and used for their chemisorption onto the gold-coated copper oxide substrate in a unified orientation at a very short distance from the hotspots. The oriented chemisorption of the protein caused significant enhancement to the signal intensity of its Raman vibration modes. This is attributed to the strong short-range electromagnetic and chemical enhancement effects that are experienced by the immobilized protein. Using this approach, label-free and reproducible SERS detection of insulin, down to 10 zM (relative standard deviation [RSD] = 5.52%), was achieved. Sixty-five percent of proteins contain disulfide bonds in their molecular structure. Therefore, the new label-free SERS detection method has strong potential for the determination of ultralow concentrations of proteins at pathology labs and in biology research.
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.JPBA.2016.12.019
Abstract: Sofosbuvir metabolite, 2'-deoxy-2'-fluoro-2'-C-methyluridine (PSI-6206) was studied for the first time by surface enhanced Raman spectroscopy (SERS) using the paper-based SERS substrate. The quantification limit of PSI-6206 by SERS was found to be 13ngL
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1AN00726B
Abstract: Duplex SERS-based lateral flow testing for C. diff bacterial infection using new biomarker, SlpA, and ToxB within 20 minutes.
Publisher: Queensland University of Technology
Date: 2018
Publisher: American Chemical Society (ACS)
Date: 30-08-2018
DOI: 10.1021/ACS.ANALCHEM.8B02121
Abstract: The detection of protein biomarkers for the clinical diagnosis of diseases requires selective and sensitive methodologies and biosensors that can be easily used at pathology laboratories and points of care. An ideal methodology would be able to conduct multimode screening of low and high concentrations of proteins in biological fluids using recyclable platforms. In this work, we demonstrate a novel nanosensing methodology for the dual detection of cystatin C (CST-C), as a protein biomarker model, in blood plasma by surface-enhanced Raman spectroscopy and electrochemistry. The new methodology utilizes the thiol chemistry of biomolecules to develop a target-specific and recyclable extractor chip for the rapid isolation of protein biomarkers from blood plasma. This is followed by the rapid reduction of the disulfide bonds within the isolated protein to influence its oriented immobilization onto a conductive gold coated silicon nanopillar substrate via stable gold-sulfur (Au-S) bonds. The oriented immobilization led to reproducible surface-enhanced Raman spectroscopy (SERS) measurements of the reduced protein (RSD = 3.8%) and allowed for its direct electrochemical determination. After the SERS measurement, differential pulse voltammetry (DPV) was used to desorb the analyte from the substrate and generate a reduction current that is proportional to its concentration. CST-C was determined down to 1 pM and 62.5 nM by SERS and DPV, respectively, which satisfies the requirements for monitoring Alzheimer's and kidney failure diseases. The new dual nanosensing methodology has strong potential for miniaturization in a lab-on-a-chip platform for the screening of many protein biomarkers that have a disulfide bond structure.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Waleed A. Hassanain.