Zirconium-based Metal-organic Framework-DNA Interactions Regulated By Site Occupancy Effects And Their Sensing Applications

Metal-organic frameworks(MOFs)are a type of crystalline porous materials with periodic network structure formed by metal ions or metal oxide clusters interconnected with organic ligands through self-assembly.MOFs have the characteristics of high specific surface area,wide porosity and variable structure.It is also the superiority of MOFs that has made this metal nanomaterial widely used in many fields such as gas storage,material separation,and disease diagnosis in the past two decades.Among them,zirconium-based MOFs(Zr-MOFs)exhibit excellent stability by virtue of the stable coordination mode of high-valent metal oxide clusters and ligands.In addition,its adjustable pore characteristics and abundant metal sites also provide convenience for its further functionalization.As a common type of biomolecule,DNA is the most commonly used substance for constructing biomolecular systems.The study of the interaction between metal organic framework and DNA is of great significance for molecular assembly.However,the current MOF-DNA interaction lacks diversity,and the combination of the two is usually achieved in a combination with poor regulatory performance.Therefore,the rational development of MOF-DNA binding mode with excellent regulation characteristics is conducive to the construction of diversified biomolecular systems and provides convenience for the construction of intelligent biosensing platforms.Phosphatases are an important class of biological enzymes.Alkaline phosphatase(ALP),as an important membrane-bound glycoprotein in organisms,which can catalyze the occurrence of dephosphorylation reactions and construct a highly selective ALP sensing strategy for related diseases.Diagnosis and research are very important.However,the detection of alkaline phosphatase is susceptible to the interference of false positive signals.It is difficult for the existing biosensing system to accurately analyze the components of the multi-component mixture in real time.Therefore,it is necessary to develop a sensing strategy to realize the difference in the mixture.Simultaneous detection of substances.By using metal nanomaterials to respond to different substances,and combining with various enzymecatalyzed reactions to generate different signal outputs,it will be as simple and efficient as possible to complete the simultaneous detection of similar functional enzymes.To this end,this research carried out the following two tasks:1.In this research,the interaction effect of different MOFs with DNA was studied by fluorescence analysis.The combination of metal-site rich Zr-MOFs(PCN-224)and fluorescent group modified single stranded DNA(F-ss DNA)was used to study the polyphosphate induced site-occupying effect of Zr-MOFs,so as to construct a MOFDNA interaction mode with excellent regulatory characteristics.Compared with the morphology and crystal structure of PCN-224 before and after interaction with DNA or sodium tripolyphosphate(STPP),MOF-DNA interaction and the introduction of STPP will not significantly affect the morphology and crystal structure of PCN-224,thus ensuring the implementation of polyphosphate guided site-occupying effect.The interaction of PCN-224 with DNA and STPP was analyzed by XPS and FT-IR.It was found that the interaction between zirconium-based MOFs(Zr-MOFs)and nucleic acids was realized through the formation of Zr-O-P,and the effective regulation of this MOF-DNA interaction could be realized through the site-occupying effect induced by polyphosphate.The introduction of phosphate can occupy the Zr atoms in zirconia clusters,which hinders the formation of Zr-O-P between PCN-224 and nucleotides,thus making MOF-DNA interaction adjustable and sensitive to polyphosphate.More importantly,the experimental results of this system show that all kinds of polyphosphates,Zr-MOFs and different types of nucleotides can be used for Zr-O-P guided MOF-DNA interaction and polyphosphate based site-occupying effect.In conclusion,this work established a general strategy to regulate MOF-DNA interaction,which provides a new idea for biomolecular assembly based on metal nanomaterials.2.In order to build a multi-functional fluorescence sensing platform for accurate detection of alkaline phosphatase,and realize the quantitative analysis of each component in the multicomponent mixture.In this system,PCN-224/F-ss DNA functional pairs were constructed by MOF-DNA interaction induced by Zr-O-P,and the fluorescence response was effectively regulated by a variety of phosphates.ALP can hydrolyze STPP step by step.Compared with STPP,the site-occupying effect of its hydrolysate is weaker,DNA is easier to combine with PCN-224 to form Zr-O-P by virtue of its phosphate skeleton.The fluorescence intensity of F-ss DNA is further quenched by fluorescence resonance energy transfer(FRET).Based on this process,the sensing strategy of ALP is finally established.The linear range is 0.5-100 U/L,and the LOD is as low as 0.19 U/L.In addition,combined with the different mechanisms of ALP and pyrophosphatase(PPase),several logic gates were established to explore the interaction between different phosphatases and phosphate substrates.Multiple logic gates were integrated to establish a complex network of logic gates to show the comprehensive regulation of different phosphates and phosphatases on MOF-DNA interaction.Based on the logic gate network,the accurate analysis of each component in phosphatase mixture was realized,and ALP and PPase could be quantified simultaneously.The proposed sensing system will contribute to the development of molecular intelligent systems and the application of logic gates in the field of biosensors.