Assembly Of Bimetallic Metal-Organic Framework Nanoprobe And Its Apllication In Bioanalysis

Metal-organic framework(MOF)has become a research hotspot in recent years due to its adjustable structure and controllable size.When MOF size reduces to the nanoscale,the character is not as same as that of original bulk MOF.Therefore,nanosized MOFs showed the promising potential applications in various fields,especially in life science.The incorporation of different metals can extend the properties and applications of MOF.Therefore,how to control the bimetallic MOF structure to make it more suitable for biological application is still a major challenge for MOF.This work focuses on the controllable assembly of bimetallic MOFs and its applications in vitro and vivo biosensing and therapy.In the first part,different from fluorescence energy resonance transfer or photoinduced electron transfer,we introduce ligand-metal charge transfer(LMCT)that often occurs in the coordination compound into MOF system for fluorescence quenching.The two-dimensional and three-dimensional structures of Fe,Pt Hoffman-type MOF(hMOF)are obtained by regulating isomeric rigid ligands.The two-dimensional MOF layers can be easily separated to monolayer in aqueous solution because of the weak hydrogen interaction between layers.hMOF nanosheets exhibited different quenching behavior to other nanosheets because the Fe sites on the backbone are axially occupied by easily substituted water molecules.We verified the LMCT mechantism of DNA quenching and successfully used it to construct a DNA sensing platform.In the second part,a MOF composite was designed with different function,and obtained a bimetallic core-shell MOF with dual response to one target for the combination therapy.By synthesizing porphyrin-based MOF(PCN-224-Cu)as core,ZIF-67 with Cu as a metal node was wrapped as shell to encapsulate the siRNA.Under the simulation of glutathione,ZIF-67(Cu)can be dissociated to release siRNA and restore the photodynamic therapy(PDT)of PCN-224,showing combination therapy of siRNA and PDT.Also,the relationship between MOF structure and therapy was proposed.