Colorimetric and electrochemical detection platforms for tetracycline based on surface molecularly imprinted polyionic liquid on Mn3O4 nanozyme

In this work, a smart tetracycline (TC) imprinted material (DSMIP@Mn3O4) is prepared via atom transfer radical polymerization of dual ionic liquid (IL) monomers on the surface of Mn3O4 nanoparticles. The obtained DSMIP@Mn3O4 shows a core-shell structure with a sphere shape and has high oxidase-like activity and recognition ability. It has been used to construct colorimetric and electrochemical detection platforms for TC. The colorimetric detection is based on the recombined TC blocking the molecular channels on the surface of DSMIP@Mn3O4, which hinders the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine to the blue product. The linear detection range is 0.5 μM-150 μM and the low detection limit is 0.1 μM. This system is further developed for the visual semi-quantitative detection of TC by using a smartphone. Furthermore, the DSMIP@Mn3O4 is combined with IL-modified carbon nanotube-graphene composite for the sensitively electrochemical detection of TC, which shows a wide linear range of 0.01 μM-20 μM and a low detection limit of 5 nM. The proposed methods have high selectivity and reproducibility and suit different detection situations. Their pracibility is evaluated by determining TC in different samples, and the measurement results are consistent with that obtained by high-performance liquid chromatography. Hence, the colorimetric and electrochemical detection platforms have good application potential.