Development and Optimisation of the Biosensor for Aspartate Aminotransferase Blood Level Determination
Overview
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This work presents the development and optimisation of an amperometric biosensor for determining aspartate aminotransferase (AST) activity in blood serum, using glutamate oxidase and platinum disc electrodes. AST is a key biomarker for diagnosing cardiovascular and liver diseases. The biosensor's bioselective membrane composition and formation protocol and the working solution (aspartate 8 mM, α-ketoglutarate 2 mM, pyridoxal-5-phosphate 100 µM) were optimised. The sensor demonstrated high selectivity, stability (70% retention over 2 months at - 18 °C), and sensitivity (2.37 nA min⁻ per 10 U L⁻), with a dynamic range of 0-500 U L⁻ and a limit of detection of 1 U L⁻. Comparative analysis showed the calibration curve method outperforms the standard addition method for AST measurement in serum samples. Additionally, a reference spectrophotometric technique was adapted for AST level determination, showing a strong correlation (r = 0.989) with the biosensor results. This research offers a fast, affordable, and accurate tool for early check-ups of liver and heart conditions. The biosensor's flexibility and ease of use make it suitable for further development into point-of-care testing and personalised healthcare techniques.