A peroxidase-like nanoenzyme based on strontium(II)-ion-exchanged Prussian blue analogue derivative SrCoO3/Co3O4 nanospheres and carbon quantum dots for the colorimetric detection of tigecycline in river water

In this work, for the first time, we derived a composite of perovskite oxide SrCoO3 and Co3O4 by annealing the Prussian blue analogue exchanged with strontium ions and modified with carbon quantum dots (CQDs). Its peroxidase-like catalytic activity was explored. The peroxidase-like activity was mainly evaluated by the rate of the chromogenic reaction. When H2O2 was present in the reaction system, the colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) was oxidized into a blue product (oxTMB), and this was monitored by UV-vis absorption spectrum. Among them, the SrCoO3 and CQDs not only promoted the generation of superoxide anion radicals (O2-•) and electron-hole pairs (h+) in the reaction system, but also accelerated the electron transfer between the substrate TMB and H2O2. Therefore, the peroxidase-like catalytic activity of the reaction system was significantly improved. Moreover, the complexation of tigecycline (TGC) and CQDs@SrCoO3/Co3O4 composite enhanced the peroxidase-like catalytic activity of the reaction system. Based on this, using TGC and TMB as template molecules, a molecularly imprinted colorimetric sensor for detecting TGC was constructed. The absorbance difference of the reaction system was linear with the TGC concentration in the range of 0.02-6.0 μM, and the detection limit was 4.46 nM. Furthermore, the proposed sensor had high selectivity and applied to the detection of TGC in Pearl River water.