Cobalt (II) porphyrin nanoaggregates as sacrificial templates to improve the peroxidase-like activity of light-controlled TiO-based nanozymes for colorimetric determination of amikacin.

Although porphyrin modification can improve the peroxidase-like activity of some inorganic nanozymes, it is hardly studied that metal porphyrin self-assembled nanoaggregates as sacrificial templates to turn on the peroxidase-like activity of inorganic nanozymes under light illumination. In this work, cobalt (II) 5,10,15,20-Tetrakis (4-carboxylpheyl)porphyrin (CoTCPP) self-assembled nanoaggregates are firstly used as soft templates to prepare TiO-based nanozymes with the enhanced peroxidase-like activity. Interestingly, CoTCPP nanoaggregates can be changed into Co oxide nanoparticles dispersed into the nanosphere composites. Furthermore, the peroxidase-like activity of CoTCPP-TiO nanospheres can be controlled by light illumination. Comparatively, CoTCPP-TiO nanoshperes exhibit the highest peroxidase-like activity of three nanospheres (CoTCPP-TiO, HTCPP-TiO and TiO) with similar morphology under the light illumination. Other than the existence of oxygen vacancy, the formation of heterostructure between TiO and a small amount of CoO are ascribed to increase the catalytic activity of CoTCPP-TiO composites. Thus, a facile and convenient colorimetric sensing platform has been constructed and tuned by light illumination for determining HO and amikacin in a good linear range of 20-100 and 50-100 μM with a limit of detection (LOD) of 3.04 μM and 1.88 μM, respectively. The CoTCPP-TiO based colorimetric sensing platform has been validated by measuring the amikacin residue in lake water.