Electrochemical study of the interaction of levofloxacin with DNA

The interaction of levofloxacin, a fluoroquinolone antimicrobial drug, with double-stranded calf thymus DNA was studied in solution by cyclic voltammetry at glassy carbon electrode. Voltammetric behavior of levofloxacin was also studied on dsDNA-modified electrodes. The binding of levofloxacin with DNA, immobilized onto the surface of an anodically activated carbon paste electrode, was exploited for designing a sensitive biosensor for levofloxacin. The response was optimized with respect to accumulation time, ionic strength, drug concentration, reproducibility and other variables. A linear dependence of the peak currents on the concentration was observed in the range of 5.0 x 10(-7) to 5.0 x 10(-6) M, with a detection limit of 1.0 X 10(-7) M. Direct and simple determination of levofloxacin in urine was established with no manipulation of urine sample other than dilution. The detection limit of the method was 25 mug ml(-1) of levolloxacin in urine. The method was validated using HPLC as a reference method. (C) 2003 Elsevier B.V. All rights reserved.