MOF-On-MOF Dual Enzyme-Mimic Nanozyme with Enhanced Cascade Catalysis for Colorimetric/Chemiluminescent Dual-Mode Aptasensing

A novel metal-organic framework (MOF)-on-MOF dualenzyme-mimicnanozyme was designed as enhanced cascade signal amplification forthe colorimetric and chemiluminescent (CL) dual-mode aptasensing.The MOF-on-MOF hybrid is composed of MOF-818 with catechol oxidase-likeactivity and iron porphyrin MOF [PMOF(Fe)] with peroxidase-like activity,called MOF-818@PMOF(Fe). MOF-818 can catalyze the 3,5-di-tert-butylcatechol substrate and produce H2O2 insitu. Subsequently, PMOF(Fe) catalyzes H2O2 toproduce reactive oxygen species, which oxidize 3,3 & PRIME;,5,5 & PRIME;-tetramethylbenzidineor luminol to produce color or luminescence. Thanks to the nano-proximityeffect and the confinement effect, the efficiency of the biomimeticcascade catalysis is greatly improved, which in turn generates enhancedcolorimetric and CL signals. Taking the detection of chlopyrifos asan example, the prepared dual enzyme-mimic MOF nanozyme is combinedwith the aptamer with specific recognition ability to develop a colorimetric/CLdual-mode aptasensor for highly sensitive and selective detectionof chlorpyrifos. The proposed MOF-on-MOF dual nanozyme-enhanced cascadesystem may provide a new pathway for the further development of abiomimetic cascade sensing platform.