Colorimetric/fluorescent dual-mode biosensor based on metalloporphyrin covalently modified NH-MIL-101(Fe) with highly efficient peroxidase-like activity for the detection of tetracycline in honey samples.

Accurate detection of tetracycline residue is of great significance for ensuring product quality and protecting human health. Here, a colorimetric/fluorescent dual-mode biosensor was developed for the detection of tetracycline in honey by using metalloporphyrin [TCPP(Fe)] covalently modified NH-MIL-101(Fe) [named NH-MIL-101(Fe)@TCPP(Fe)]. The morphology, chemical structure and peroxidas-like activity of this hybrid nanozyme were comprehensively studied. Based on excellent catalytic activity and intrinsic fluorescence of NH-MIL-101(Fe)@TCPP(Fe), a colorimetric/fluorescent dual-mode biosensor was developed for the detection of tetracycline. The primary mechanism for this dual mode biosensor was the inhibitory effect of tetracycline on on NH-MIL-101(Fe)@TCPP(Fe) catalyzed chromatic reaction between HO and 3,3',5,5'-tetramethylbenzidine (TMB)/o-phenylenediamine (OPD), which was ascribed to the consumption of ·OH by tetracycline and the adsorption of tetracycline on the surface of NH-MIL-101(Fe)@TCPP(Fe). After effective validation, this colorimetric/fluorescent dual mode method was applied to detect tetracycline residues in three actual honey samples.