Zeolitic Imidazolate Framework-8 Grown on Nanoporous SiO₂ with Aptamer Functionalization for Selective Isolation of Thrombin

A three-dimensional ordered macroporous composite (3DOM SiO2@ZIF-8-TBA) was fabricated via the in situ growth of metal–organic framework ZIF-8 (∼50 nm) on the surface of macroporous SiO2 (pore size of ∼250 nm) and the subsequent functionalization with a thrombin aptamer. The obtained 3DOM SiO2@ZIF-8-TBA composite has been proven to be a potential protein-enriching adsorbent, which exhibits high selectivity toward the adsorption of thrombin due to the specific conformation between the aptamer and thrombin. The adsorption behavior of thrombin onto the 3DOM SiO2@ZIF-8-TBA composite conforms to the Langmuir adsorption model, resulting in a superior adsorption capacity of 40.9 U mg–1, contributed by the ordered macroporous structure. The retained thrombin could be readily recovered by 1.0% NH3·H2O (m/v) with a recovery of 92.3%. Circular dichroism spectra illustrate that the 3DOM SiO2@ZIF-8-TBA composite-based adsorption/desorption processes have no influence on thrombin conformation. The application of the 3DOM SiO2@ZIF-8-TBA composite in separating thrombin from human serum has been verified; fibrin production tests prove that the activity of recovered thrombin is well retained.