Biosensors Based On Hierarchical Petal MOF Nanostructures And Enzymatic Catalysis And Their Analytical Applications

Metal organic frameworks（MOF）composites have unique physical and chemical properties,such as adjustable pore sizes,stable framework structures,large specific surface areas and so on,which make them become a kind of functional materials widely used currently.However,the conductivity and water solubility of MOF are not very superior,which affects its further applications especially in electrochemical biosensors.The effective combination of MOF and other nanomaterials can make up for the lack of single-material performances,give full play to the advantages of various materials,and make MOF composites have broader application prospects in the significant field of electrochemical biosensors.In this paper,based on the preparation and applications of electrochemical nanobiosensors,new electrochemical biosensors were constructed by using MOF and other functional nanomaterials to determine tumor marker stress-induced phosphoprotein 1（STIP1）and uric acid（UA）at low concentration ranges.The specific research contents are available as follows:One:In this work,we report the preparation of Mn-doped Ni-based metal-organic frameworks（Mn-MOF）through solvothermal synthesis,with 3D hierarchical flower-like superstructures.Mn-MOF was assembled with 2D black phosphorous nanosheets（BPNSs）to achieve novel 2D/3D BPNSs/Mn-MOF nanocomposites,followed by the direct coupling of methylene blue-labeled DNA aptamer on the interface of glassy carbon electrode（GCE）modified with the nanocomposites.The aptamer/BPNSs/Mn-MOF/GCE platform was utilized for precise capture and efficient detection of STIP1.Experimental results confirmed that Mn-doping induced the hierarchical petal growth of the flower-like3D MOF and its assembly with BPNSs.GCE surface modifications with various components were studied through measuring electrochemical curves.The morphologies,microstructures and spectra of products were characterized.The optimal conditions used for electrochemical measurements were assessed.A smart aptasensor was explored by aptamer/BPNSs/Mn-MOF/GCE that had multiple attractive merits,including the synergistic effects of components,porous superstructures of hierarchical flower-like 3D Mn-MOF and specific aptamer-target recognition.The merits endowed the aptasensor with selective and sensitive signal responses to STIP1 over interferences.The aptasensor enabled efficient detection of STIP1 in a broad range of 2×10^-3–1×10⁴ ng m L^-1,accompanied by a low limit of detection（LOD）of 1 pg m L^-1.Two:In this work,a facile one-pot precipitation was used to prepare a petal-shaped3D hybrid in mild sytnehsis conditions.The hybrid is composed of urate oxidase（UOx）encapsulated into zeolite-like metal-organic frameworks（MOF）with doping of hollow gold nanocage（Au NC）.As one of MOF-enzyme composites,the UOx@MOF（Au NC）hybrid with features of artificial nano-enzymes was developed as a novel dual-channel biosensing platform for fluorescence（FL）and electrochemical detection of UA.As for FL biosensing,enzymatic catalysis of hybrid in the presence of UA triggered tandem catalysis and oxidization reactions to cause FL quenching.UA was linearly detected in the concentration ranges of 0.1–10μM and 10–300μM,with a LOD of 20 n M.As for electrochemical biosensing,the hybrid was dropped onto GCE surface to construct hybrid/GCE platform facilely.Based on redox reaction of UA on the platform surface,UA was linearly detected in the concentration range of 0.05–55μM,with a LOD of 15n M.Experimental results confirm that hybrid-based dual-channel biosensing platform enabled selective and sensitive responses on UA over interferents.The platform shows an excellent detection capability in physiological samples,together with great feasibility and practicability.The petal-shaped 3D MOF hybrid can be extended to other oxidases and peroxidases to realize the enzymatic catalysis-based FL biosensing of relevant substrates in well combination with electrochemical biosensing mode.