Molecularly-Imprinted Materials for Potentiometric Transduction: Application to the Antibiotic Enrofloxacin

Abstract

Enrofloxacin (ENR) is an antimicrobial used both in humans and in food producing species. Its control is required in farmed species and their surroundings in order to reduce the prevalence of antibiotic resistant bacteria. Thus, a new biomimetic sensor enrofloxacin is presented. An artificial host was imprinted in specific polymers. These were dispersed in 2-nitrophenyloctyl ether and entrapped in a poly(vinyl chloride) matrix. The potentiometric sensors exhibited a near-Nernstian response. Slopes expressing mV/Δlog([ENR]/M) varied within 48–63. The detection limits ranged from 0.28 to 1.01 µg mL⁻¹. Sensors were independent from the pH of test solutions within 4–7. Good selectivity was observed toward potassium, calcium, barium, magnesium, glycine, ascorbic acid, creatinine, norfloxacin, ciprofloxacin, and tetracycline. In flowing media, the biomimetic sensors presented good reproducibility (RSD of ± 0.7%), fast response, good sensitivity (47 mV/Δlog([ENR]/M), wide linear range (1.0 × 10⁻⁵–1.0 × 10⁻³ M), low detection limit (0.9 µg mL⁻¹), and a stable baseline for a 5 × 10⁻² M acetate buffer (pH 4.7) carrier. The sensors were used to analyze fish samples. The method offered the advantages of simplicity, accuracy, and automation feasibility. The sensing membrane may contribute to the development of small devices allowing in vivo measurements of enrofloxacin or parent-drugs.

Keywords:

• Enrofloxacin
• Fia
• Fish
• Molecularly-imprinted sensors
• Potentiometry

Acknowledgments

The authors acknowledge the financial support from FCT, Fundação para a Ciência e Tecnologia/FEDER, by means of project PTDC/AGR-AAM/68359/2006. A. H. Kamel is grateful for the post-doctoral grant (SFRD/BPD/38740/2007).

Notes

R²: correlation coefficient; LOD: limit of detection; LLLR: lower limit of linear range; σ: standard deviation; MIP: molecularly-imprinted polymer; NIP: non-imprinted polymer; MAA: methacrylic acid; VP: 2-vinyl pyridine; and TpC1PB: potassium tetrakis(4-chlorophenyl)borate.