Disposable and Inexpensive Electrochemical Biosensor to Detect Ciprofloxacin

Abstract

Ciprofloxacin hydrochloride, USP, a fluoroquinolone, is the monohydrochloride monohydrate salt of 1-cyclopropyl-6-fluoro-1, 4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid. Ciprofloxacin (Cipro) is an antibacterial medicine used to treat infected open wounds, by targeting bacteria infiltrating and rendering useless to multiplying using attacking its genetic makeup directly. In 2010, over 20 million prescriptions were written, making it the 35th-most commonly prescribed generic drug and the 5th-most commonly prescribed antibacterial in the U.S. There is also a huge demand for the inexpensive and compact sensor to detect the presence of ciprofloxacin in water. Its wide use motivated us to develop an electrochemical sensor to detect the presence of the ciprofloxacin in aqueous solutions. Inexpensive and disposable screen-printed electrode was used as our electrochemical sensor. We tested different aqueous solutions with varying concentrations of Cipro, and measure the sensitivity. The sensors have three electrodes, with the working and counter electrode being composed of graphite, and the reference electrode composed of Ag/AgCl and sodium hydroxide (NaOH) is the supporting electrolyte. During the preparation of the Ciprofloxacin, NaOH is added in order to neutralize, which also acts as a supporting electrolyte. Finally, Cipro is then added to 2mL of DI water and disturbed until a solution is formed. The prepared solution is varied for the desired concentration is then drop-coated onto the sensing part in the electrochemical sensor, making sure the entirety of the sensing section is covered. The sensor is then connected to the potentiostat, and the test is performed. The redox reaction was measured using a potentiostat (Biologic). With these different concentrations, testing was conducted through the use of cyclic voltammetry (CV) and chronoamperometry (CA). From the CV curves, we were able to determine the relationship between the concentrations(nM) and the current. Our data shows that the current has a steady decrease as the concentrations increase. The slope provided from this relationship is used to provide the sensitivity of the testing method produced. The sensitivity was measured to be found to be .0029nM over a linear range of (0.1nM - 2nM).