Ibrahim Abu-Shqair is the second postgraduate student to be awarded a PhD degree from the University this year. He graduated on a dissertation entitled: “Determination of Fluoroquinolone Antibacterials with DNA-Modified Electrodes, and Their Oxidation by Potassium Hexacyanoferrate.” His dissertation was supervised by Prof. Radi Daoud and co-supervised by Prof. Mohammad Al-Subu.
Dr. Abu-Shqair briefly explains his dissertation topic:
“My dissertation is based on UV-visible spectroscopic and electrochemical methods, which I used to study the interaction of certain fluoroquinolones with calf-thymus DNA. UV-visible spectroscopy was used to evaluate the binding constants of these drug/DNA complexes and to elucidate the nature of the bindings. The interaction of the selected fluoroquinolones with the DNA was investigated at a glassy carbon electrode with an irreversible electrochemical equation through cyclic voltammetry. The diffusion coefficients of both free and bound fluoroquinolones (Df, Db), the binding constant (K), and the binding site size (s) of the fluoroquinolone-DNA complexes were obtained simultaneously by non-linear fit analysis of the experimental data. The results suggest that fluoroquinolones bind to DNA through an electrostatic mode of interaction with partial intercalation.
My research pioneers the use of DNA-modified glassy carbon electrodes as a biosensor for the analysis of the studied compounds. Differential-pulse anodic stripping voltammetry was used for investigating different factors affecting the oxidation of the studied fluoroquinolones at the DNA-biosensor. A method was proposed for the determination of ciprofloxacin concentration in both tablets and in a biological fluid (urine). The method was found to be sensitive, accurate, and inexpensive.
My dissertation also investigates the kinetics of osmium tetroxide-catalyzed oxidation of the studied fluoroquinolones by potassium hexacyanoferrate (III) in an alkaline medium. The rate was found to be independent of the concentration of hexacyanoferrate (III), and of the first order with respect to both fluoroquinolone and OsO4. An empirical rate law was derived for the reaction, and the effect of various variables on the rate of reaction was studied. Thermodynamic parameters (Ea, ؤH*, ؤS*, ؤG*) were also calculated.”