An electrochemical aptasensor electrocatalyst for detection of thrombin

This work reports a novel signal amplification strategy based on three-dimensional ordered macroporous C₆₀-poly(3,4-ethylenedioxythiophene)-1-butyl-3-methylimidazolium hexafluorophosphate (3DOM C₆₀-PEDOT-[BMIm][BF₆]) for ultrasensitive detection of thrombin by cascade catalysis of Au-PEDOT@SiO₂ microspheres and alcohol dehydrogenase (ADH). Au-PEDOT@SiO₂ microspheres were constructed not only as nanocarriers to anchor the large amounts of secondary thrombin aptamers but also as nanocatalysts to catalyze the oxidation of ethanol efficiently. Significantly, the electrochemical signal was greatly enhanced based on cascade catalysis: First, ADH catalyzed the oxidation of ethanol to acetaldehyde with the concomitant generation of NADH in the presence of β-nicotinamide adenine dinucleotide hydrate (NAD⁺). Then, gold nanoparticles (AuNPs) as nanocatalysts could effectively catalyze NADH to produce NAD⁺ with the help of PEDOT as redox probe. Under the optimal conditions, the proposed aptasensor exhibits a linear range of 2 × 10^-13 to 2 × 10^-8 M with a low detection limit of 2 × 10^-14 M for thrombin detection and shows high sensitivity and good specificity.