Synthesis and biosensor application of poly[(methoxyethoxy)ethoxy-co-3-formylphenoxy] phosphazene

An amperometric glucose biosensor was prepared successfully based on a conducting polymer; poly[4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzenamine] (poly(SNS-NH2)) and a new flexible hydrophilic polyphosphazene polymer, poly[(methoxyethoxy)ethoxy-co-3-formylphenoxy]phosphazene (PPA). Poly(SNS-NH2) was electrochemically polymerized on a graphite electrode to achieve a conducting immobilization matrix to improve the enzyme immobilization on the transducer surface. Moreover, to enhance the immobilization, a polyphosphazene derivate bearing functional aldehyde group was designed, synthesized and used in the immobilization of glucose oxidase. Not only the amino groups in the structure of poly(SNS-NH2), but also the aldehyde groups in PPA were contributed to the covalent immobilization as well as the entrapping the biomolecules in PPA network during the immobilization process. This afforded an effective and long-life analysis to glucose. Amperometric measurements were conducted at -0.7 V vs. Ag/AgCl in 50 mM sodium acetate buffer at pH 4.5. KMapp (0.677 mM), Imax (20.91 µA) and LOD (1.3 µM) values were determined. Moreover, biosensor showed an extremely high sensitivity as 237.1 µA mM-1 cm-2 owing to the newly synthesized and combined highly flexible hydrophilic polyphosphazene immobilization matrix. Finally, the proposed biosensor was successfully applied for determination of glucose content in several beverages.