Studies towards an amperometric phosphate ion biosensor for urine and water analysis

Using the interfacial barrier effects of p-n junction on electrochemistry for detection of phosphate

A novel type of electrochemical sensor for detection of phosphate in water environment was developed by combining the interfacial barrier of p-n junction with the adsorption of phosphate. The electrochemical response was produced by the induced change of the barrier height, which was only caused by the specific adsorption of phosphate. Two linear concentration ranges (0-0.045 mg L^-1 and 0.045-0.090 mg L^-1) with two sensitivities (4.98 μA (μg L^-1)^-1 and 1.28 μA (μg L^-1)^-1) were found. The good performance made the sensor meet the requirements of the World Health Organization for drinking water (1 mg L^-1 of phosphate). It is an approach to develop electrochemical sensors by employing the interfacial barrier effects on electrochemistry.

A novel ultrasensitive phosphate amperometric nanobiosensor based on the integration of pyruvate oxidase with highly ordered gold nanowires array

A novel phosphate amperometric nanobiosensor, based on an intimate integration of pyruvate oxidase (PyOx) and its cofactors, thiamine pyrophosphate (TPP) and flavin adenine dinucleotide (FAD), with a highly ordered gold nanowires array (AuNWA) has been developed. The successful integration of PyOx and the co-factors, via crosslinking with bovine serum albumin (BSA) and glutaraldehyde (GLA), onto the AuNWA was confirmed by cyclic voltammetry and amperometry. The resulting nanobiosensor achieved a detection limit of 0.1 µM, a linear concentration range of 12.5-1000 µM, and a sensitivity of 140.3 µA mM(-1)cm(-2). Notably, the incorporation of the AuNWA reduced the required PyOx concentration by 70-120 fold and the presence of common interferants, such as chloride, sulfate, fluoride, nitrite and nitrate ions did not interfere with phosphate detection. Furthermore, the nanobiosensor demonstrated a very high stability with repeated use over two weeks and was successfully used for the determination of phosphate in water samples with an average recovery of 96.6 ± 4.9%.