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Ciprofloxacin (Cf) is a synthetic fourth generation fluoroquinolone class antibiotic used for the treatment of gram-positive, gram-negative and mycobacterium species infections. Electrochemical characteristic of the Cf antibiotic on carbon nanotube modified glassy carbon electrode (GCE/CNT) in pH 7 phosphate buffer solution has been investigated. Electrochemically oxidized radical byproduct of the Cf drug, which is formed as intermediate, gets immobilized on the GCE/CNT (GCE/Cf@CNT) and showed stable and well defined surface confined redox peak at -0.220 V versus Ag/AgCl. Control electrochemical experiment with unmodified GCE failed to show any such immobilization and redox features. Physicochemical characterizations of the Cf@CNT by transmission electron microscope, scanning electron microscope, infrared spectroscopy, UV-Vis and gas chromatography coupled mass spectroscopic analyses of Cf@CNT collectively revealed presence of native form of the Cf antibiotic molecule onto the CNT. The interaction between the Cf molecule and the CNT tubes are revealed from the decreased intensity in the Raman spectrum. The GCE/Cf@CNT showed excellent electrocatalytic response to hydrogen peroxide reduction reaction in pH 7 phosphate buffer solution. Amperometric i-t analysis for the detection of H2O2 showed a current linearity plot upto [H2O2] = 200 μM at an applied potential - 0.1 V versus Ag/AgCl with a current sensitivity value 678 μA mM(-1) cm(-2). No interferences were noticed with ascorbic acid, uric acid, cysteine and nitrite. The present study can be highly helpful to understand the interaction between the Cf and H2O2 in physiological systems and for the removal of Cf from the antibiotic polluted water samples especially in the aquaculture and agricultural systems.

An electrochemical route for highly selective immobilization of a β-lactam family antibiotic, amoxicillin (AMX), from the other drugs, penicillin and ampicillin, on multiwalled carbon nanotube modified glassy carbon electrodes (GCE/AMX@MWNT), without any linkers and surface functionalization, has been successfully demonstrated. The electrochemical response of the AMX on GCE/MWNT showed an irreversible oxidation peak at 0.5 V vs. Ag/AgCl (A1), followed by the growth of a new redox peak at 0 V vs. Ag/AgCl (A2/C2) in pH 7 phosphate buffer solution, which is in parallel to a control phenol electrochemical response, revealed that the phenoxy radical electrogenerated at A1 gets subsequently adsorbed on the underlying MWNT modified electrode with a specific surface confined A2/C2 redox peak with proton-coupled electron transfer behaviour. Physicochemical characterization from X-ray diffraction, transmission electron microscopy and scanning electron microscopy collectively evidenced the immobilization of AMX both on the inner and outer (surface) walls of the carbon nanotubes. Further, the AMX@MWNT hybrid material was found to show enhanced antibacterial activity against three bacterial pathogens, Escherichia coli, Staphylococcus aureus and Bacillus subtilis, over the unmodified AMX and MWNT. Finally, as an environmental pollution remedy, the uptake of the AMX drug from five different simulated sources: river water, sea water, river soil, sea soil and farm milk, was successfully demonstrated by this new electrochemical methodology.