Development of amperometric immunoassays (AIAs) for calpastatin and μ-calpain with possible applications in the biomedical field

Due to the involvement of calpains and calpastatin in the pathology of several diseases, it is important to create an analytical tool for their accurate and sensitive measurements. In this work, an amperometric immunoassay (AIA) was developed and optimized for quantification of two key proteins from the calpain proteolytic system. The detection is based on the measurement of a steady-state current on screen printed electrodes due to the reduction of the enzymatic product resulting from specific immunoassays, where the measured current is proportional to the concentration of the target analyte. The optimized assays with dynamic ranges from 0.09 to 6 ng/mL for calpastatin and 0.04 to 5 μg/mL for calpain, offer simplicity, sensitivity and possibility for miniaturization.