Innovative hybrid molecularly imprinted sensor for the detection of the antioxidant biomarker catalase

In this study, a novel hybrid molecularly imprinted polymer (MIP)-based biomimetic sensor was fabricated, optimized, characterized, and applied for the electrochemical recognition of catalase (CAT), an antioxidant biomarker. A layer-by-layer approach was followed to prepare the hybrid sensor. First, silver nanoparticles (AgNPs) were deposited by chronoamperometry on a bare glassy carbon electrode (GCE) for 300 s, followed by drop-casting of multi-walled carbon nanotubes (MWCNTs). The MIP was then produced by ten voltammetric electropolymerization cycles using ortho-aminophenol (OAP) as a functional monomer in the presence of catalase as a template on the MWCNT/AgNP/GCE surface at a potential range of -0.2 V to 0.8 V. The fabricated sensor exhibited a rapid response toward CAT within a linear range of 25-500 U/mL and a limit of detection (LOD) of 3.59 U/mL, with no cross-reactivity toward several tested possible biological species. CAT was also successfully detected in biological samples, with recovery percentages ranging from 95.73% to 101.60% and relative standard deviation (RSD) of 0.41-1.52%, which is comparable to the results for a commercial diagnostic reference kit, without the need for complicated sampling procedures. The sensor performance is dependent on catalase molecular recognition rather than reactivity towards its substrate. This feature, in addition to the sensor's low cost and portability, positions it as a promising candidate for use in point-of-care diagnostics in the medical field.