DESIGN AND CHARACTERIZATION OF A GALACTOSE BIOSENSOR USING A NOVEL POLYPYRROLE-HYDROGEL COMPOSITE MEMBRANE

ABSTRACT

A rapid, two-step method for constructing galactose biosensors by entrapment of galactose oxidase within a polymeric composite has been developed. The composite material is formed as an interpenetrating network of polypyrrole grown within a UV cross-linked poly(2-hydroxyethyl methacrylate) [p(HEMA)] hydrogel. The optimized galactose biosensor exhibited a linear response range from 5.0 × 10⁻⁵ to 1.0 × 10⁻² M and detection limit of 25 µM toward galactose. The response time of the biosensor was 70 s. The analytical recovery of galactose in serum samples ranged from 97 to 105% with mean coefficients of variation of 3.8% (within-day analyses) and 4.4% (day-to-day analyses). The biosensor was effective in screening up to twice the physiological levels of ascorbate, urate and acetaminophen interferents and retained 70% of initial enzyme activity after 9 months when stored desiccated in the absence of buffer at 4°C.

Keywords:

• Galactose biosensor
• Galactose oxidase
• Polypyrrole
• Hydrogel composite

ACKNOWLEDGMENTS

The authors gratefully acknowledge the VCU Center for Bioelectronics, Biosensors and Biochips (C3B), the Virginia Center for Innovative Technology (CIT BIO-99-010) and ABTECH Scientific, Inc. for financial support. SB thanks Lebert Grierson for useful discussions and the University of the West Indies for a post-graduate scholarship.