Electrochemical study of the interaction of levofloxacin with DNA Original Research Article

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 5.0×10−7 to 5.0×10−6 M, with a detection limit of 1.0×10−7 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 μg ml−1 of levofloxacin in urine. The method was validated using HPLC as a reference method.