The Construction And Analysis Application Of Optical Sensor System Based On CTF/MOF Nanozymes

Natural enzymes as a biocatalyst are widely used in biosensor,health and medicine,and environmental protection owing to their excellent catalytic efficiency and outstanding substrate specificity.However,their intrinsic vulnerabilities,such as low stability,high cost of preparation and harsh storage conditions,severely hamper their widespread technical application.Since Yan reported the magnetic iron oxide nanoparticles possess peroxidase-like catalytic activity in 2007,which employed nanoparticles as mimic enzymes have received much attention.Many nanomaterials,such as oxide nanomaterials,carbon nanomaterials,noble metal nanomaterials and metal-organic framework（MOF）displayed intrinsic mimetic activity.Compared with natural enzymes,nanozymes have several advantages,such as low cost,ease of preparation and good stability.So far,The development of nanozymes have made great progress,but there are still some deficiencies.For example,the catalytic efficiency of existing nanozymes is generally low.Therefore the development of peroxidase mimics with precise regulation of catalytic activity remains a challenging task.In addition,nanozymes have shown promising applications in the field of fluorescence sensing.However,the label-free fluorescent sensors remain to be developed based on the multi-functional nanozymes.In this dissertation,a method for precisely regulating the activity of nanozymes was developed and two label-free fluorescent sensors were constructed for the detection of small molecules based on dual-functional MOF nanozymes.The main contents are as follows:1.First,we employed a microwave-enhanced high-temperature ionothermal method for the facile synthesis of the CTF.Then,the copper-modified CTF（CCTF）was prepared by an inexpensive and mild post-synthetic modification strategy using copper ions.Owing to its unique specific surface area,atomically dispersed active Cu sites,efficient electron transfer,and enhanced photo-assisted enzyme-like activity,the CCTF showed enhanced peroxidase-like enzyme activity.Therefore,copper modification represents an effective route to tailor the peroxidase-like activity of the covalent triazine framework.Furthermore,the mechanism of the enhanced peroxidase-like activity and stability of the CCTF were investigated.As a proof of concept,the CCTF was used for the colorimetric detection of H₂O₂ and decomposition of organic pollutants.This work provides a new strategy for the design of enzyme mimics with a broad range of potential applications.2.MIL-53（Fe）was prepared by a simple solvothermal method and a novel label-free fluorescent sensor based on MIL-53（Fe）nanozyme was constructed for the determination of H₂O₂and glucose.In this system,MIL-53（Fe）is not only a catalyst,but also a fluorescent probe.Under optimum conditions,the proposed method allowed the detection of H₂O₂in the range of 0.5-24μmol L^-1 and glucose in the range of 0.5-27μmol L^-1 with detectable as low as 7.54×10^-3μmol L^-1 and glucose as low as 8.44×10^-3μmol L^-1,respectively.This method is used to determine glucose in human serum and the result is consistent with those obtained by using the conventional enzymatic method.The proposed strategy does not need to be used in combination with horseradish peroxidase,chromogenic reagents and rare metals,and showed the advantages of low cost and safety.3.Luminescent Fe-MIL-88NH₂was prepared by a simple solvothermal method using 2-aminoterephthalic acid and ferric chloride hexahydrate as recursors.A label-free fluorescence platform for rapid and sensitive determination of catechol was investigated based on the excellent peroxidase activity of Luminescent Fe-MIL-88NH₂.Under optimum conditions,the proposed method allowed the detection of catechol in the range of 0.125-5μmol L^-1（R²=0.9988）with detectable catechol as low as 0.0913μmol L^-1.The proposed method showed performance advantages of fine selectivity,high sensitivity and low detection limit.It will hold an enormous potential in the field of environmental analysis.