Browsing by Author "Salam, Faridah"

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    Detection of Salmonella typhimurium using an electrochemical immunosensor.
    (Elsevier Science B.V., Amsterdam., 2009-04-15T00:00:00Z) Salam, Faridah; Tothill, Ibtisam E.
    An electrochemical immunosensor based on screen-printed gold working electrode with onboard carbon counter and silver–silver chloride pseudo-reference electrode for Salmonella typhimurium detection is described in this paper. Monoclonal anti-S. typhimurium antibody was immobilized using physical and covalent immobilization via amine coupling of carboxymethyldextran on the surface of the gold working electrode. A direct sandwich enzyme-linked immunosorbent assays (ELISA) format was then developed and optimized using a polyclonal anti-Salmonella antibodies conjugated to horseradish peroxidase (HRP) as the enzyme label. 3,3′,5,5′-Tetramethylbenzidine dihydrochloride (TMB)/H2O2 was used as the enzyme mediator/substrate system. Electrochemical detection was conducted using chronoamperometry at −200 mV vs. onboard screen-printed Ag–AgCl pseudo-reference electrode. The applied potential was selected through the study of the electrochemical behaviour of bare gold electrode with TMB–H2O2–IgG–HRP system. S. typhimurium detection of 5 × 103 cells ml−1 and 20 cells ml−1 was achieved respectively for physical and covalent antibody immobilization. The developed sensor was then compared to a commercial ELISA kit and a chromogenic agar plating method for meat samples analysis. The sensor format shows a promising technology for simple and sensitive detection system for Salmonella contamination. Rapid detection of Salmonella is a key to the prevention and identification of problems related
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    Detection of β-amyloid peptide (1–16) and amyloid precursor protein (APP770) using spectroscopic ellipsometry and QCM techniques: A step forward towards Alzheimers disease diagnostics
    (Elsevier, 2010-12-15) Mustafa, M. K.; Nabok, Alexei; Parkinson, D.; Tothill, Ibtisam E.; Salam, Faridah; Tsargorodskaya, A.
    A highly sensitive method of spectroscopic ellipsometry in total internal reflection mode (TIRE) was exploited for detecting β-amyloid peptide (Aβ1–16) in the direct immune reaction with monoclonal DE2 antibodies (raised against Aβ1–16) electrostatically immobilised on the surface of gold. A rapid detection of Aβ1–16 in a wide range of concentrations from 5 μg/ml down to 0.05 ng/ml was achieved using a cost-effective and label-free direct immunoassay format. TIRE dynamic spectral measurements proved that the immune reaction between DE2 monoclonal antibodies and Aβ1–16 is highly specific with the affinity constant KD = 1.46 × 10−8 mol/l. The same DE2 antibodies were utilised for detection of amyloid precursor protein APP770, a larger protein containing Aβ1–16 domain, using the quartz crystal microbalance (QCM) measurements in liquid. A combination of QCM and TIRE kinetics results allowed the evaluation of the originally unknown concentration of APP770 in complete medium solution containing other proteins, salts, and amino acids.
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    Development of immunosensors for salmonella typhimurium
    (Cranfield University, 2010-03) Salam, Faridah; Tothill, Ibtisam E.
    The accidental contamination of Salmonella in raw and processed foods is a major problem for the food and feed industries worldwide. Rapid detection methods for monitoring and identification are required to solve the health and safety problems related to these pathogenic bacteria. Current detection methods require extensive sample preparation and prolonged assay procedures, thus, this research project focused on developing rapid methods which are capable of sensing these microorganisms at a high sensitivity level. Cont/d.