Determination of ciprofloxacin with functionalized cadmium sulfide nanoparticles as a fluorescence probe

A novel assay of ciprofloxacin with a sensitivity at the microgram level is proposed based on the measurement of enhanced fluorescence intensity signals resulting from the interaction of functionalized nano-CdS with ciprofloxacin. The CdS nanoparticles was synthesized by thioacetamide (TAA) and cadmium nitrate (Cd(NO3)2) in the alkaline solution. At pH 7.4, the fluorescence signals of functionalized nano-CdS were greatly enhanced by ciprofloxacin with the increase concentration of ciprofloxacin. Linear relationship can be established between the enhanced fluorescence intensity and ciprofloxacin concentration in the range of (1.25–8.75) × 10−4 mg mL−1 ((3.77–26.4) × 10−4 mmol L−1) or (8.75–1200) × 10−4 mg mL−1 ((26.4–3625) × 10−4 mmol L−1). The limit of detection is 7.64 × 10−6 mg mL−1 (2.31 × 10−5 mmol L−1). Based on this, a new direct quantitative determination method for ciprofloxacin in human serum samples without separation of foreign substances was established. The contents of ciprofloxacin in human serum samples were determined with recovery of 95–105% and relative standard deviation (R.S.D.) of 1.5–2.5%. This method was proved to be very sensitive, rapid, simple and tolerance of most interfering substances.