A facile nanozyme based catalytic platform for the selective and sensitive detection of thrombin

Herein, a label-free and ultra-sensitive sensing strategy was proposed for the colorimetric detection of thrombin. A catechol oxidase-mimicking nanozyme, MOF-818, was in-situ uniformly synthesized on carbon cloth (CC) fibers surface by hydrothermal method, which did not aggregate during the colorimetric sensing and showed high catalytic activity to the oxidation of faint yellow colored substrate 3,5-Di- tert -butylcatechol (3,5-DTBC) to luminous yellow colored 3,5-di- tert -butyl- o benzoquinone (3,5-DTBQ). After the conjugation of aptamer on MOF-818/CC, the nanozyme composite can effectively recognize and bind thrombin, resulting in the lighter color of substrate solution and the decrease of absorbance at 414 nm. Thus, the inhibition of the nanozyme activity by the bound thrombin was employed to detect thrombin in a wide linear range and a low limit of detection of 1.4 × 10 −10 M − 1.4 × 10 −5 M and 6.4 pM, respectively, which was superior to the most of reported methods including fluorescence and electrochemical sensing, Raman spectroscopy. Meanwhile, the nanozyme composite can be easily separated from the substrate solution by a tweezers instead of the conventional centrifugation, which greatly simplified the operation process and facilitated the on-site detection. The nanozyme composite has been successfully applied for the determination of thrombin in real samples with satisfactory results. Consequently, this work is not only important for a better understanding of the unique properties of MOF-818, but also has great potential for medical diagnosis and treatment of human health.