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Abstract: A novel approach towards the development of biomimetic electrochemical sensors is presented. It is based on magnetic-core/porous-shell molecularly imprinted composites as recognition phase. The selected substrate is 5-hydroxyindole-3-acetic acid (5-HIAA), an urinary metabolite used as carcinoid tumor maker. Using 5-HIAA as template molecule, hemin, 4-vinylpyridine and ethylenglycoldimethacrylate crosslinker are polymerized onto the magnetic core to obtain an artificial enzyme with peroxidase activity. An aliquot of a suspension of the resulting material is deposited onto a carbon screen printed electrode, and the solid material is fixed with a permanent magnet to prepare the sensor. The product of the catalytic oxidation of 5-HIAA at the sensing phase is monitored by differential pulse voltammetry. This sensor allows the detection of 5-HIAA with good sensitivity (0.72 ± 0.01 nA μM-1) and linear response over a concentration range covering the whole window of normal and pathologic urinary levels of 5-HIAA 1-50 μM (0.2-9.6 ppm) with a detection limit of 1.4 μM (0.27 ppm). Urine samples of healthy individuals, spiked with known concentrations of 5-HIAA, yield good recovery values and reproducibility for normal and pathological concentrations (90-100% recovery values, with RSD below 10%)
Template and target information: 5-hydroxyindole-3-acetic acid, 5-HIAA
Author keywords: artificial enzyme, Molecularly imprinted catalytic polymer, Peroxidase-like catalyst, Core-shell magnetic particles, Electrochemical sensor