The Synthesis Of Dicarboxylic Phenanthroline Based Metal-organic Gels And Their Analytical Applications As Mimic Enzyme

Natural enzymes are present in most life forms by catalyzing and accelerating chemical reactions in metabolic processes with high efficiency and selectivity.However,the disadvantages of the high cost,variability and harsh conditions of use of natural enzymes greatly limit their use.Nanozymes with low cost,easy preparation,stable nature and high catalytic activity have emerged,which effectively overcome the shortcomings of natural enzymes and open a new chapter in the research of nanomaterial properties.Metal-organic gels are the emerging class of non-flowing and stable metal oganic soft materials that rely on metal-organic coordination and supramolecular interactions to encapsulate the solvent molecules.MOGs combine the excellent properties of semi-solid gels and metal ions,possess unique optical,electronic,magnetic,catalytic and multiple-stimulus responsive properties,and its structure gives it a large specific surface area,porosity and abundant exposed active metal sites.Moreover,benefit from these distinct properties,MOGs has been widely used in adsorption,catalysis,analytical detection and biomedical fields.However,the application of MOGs as catalysts in the field of catalysis is limited to organic catalysis,and MOGs with mimetic enzyme catalytic activity have not been reported.Therefore,this thesis devoted to the synthesis of MOGs and the composites based on the coordination and self-assembly between the carboxyl group-containing phenanthroline ligand and Fe??? and Ru???,and investigated their application in pharmaceutical analysis as mimetic enzyme.This thesis includes the following three parts:1.The preparation of Fe-MOGs with active mimic enzyme for the detection of dopamine.Novel Fe???-based metal-organic gels with platelet-like structure has been fabricated by the direct gelation of Fe³⁺ and 1,10-phenanthroline-2,9-dicarboxylic acid.By employing a simple freeze-drying method,the obtained Fe-MOXs were first demonstrated excellent oxidase-like catalytic activity for prompting the decomposition of dissolved oxygen to yield oxygen-related radicals,leading to a dramatic CL emission.Since DA is readily reacted with the active oxygen radicals,resulting in the inhibition of luminol oxidation process and the reduction of chemiluminescence,we have established a simple chemiluminescence detection method for the sensitive detection of dopamine in urine samples.Under the optimal detection conditions,the chemiluminescence intensities has a linear relationship with glucose concentration from 0.05?M to 0.6?M with a detection limit of 20.4 nM.2.The preparation of AuNPs/MOGs?Fe? composites with synergistically enhanced mimetic enzyme activity for the chemiluminescence detection of organophosphorus pesticides.Inspired by that abundant unsaturated metal-active center of MOGs?Fe? can be complexed with a phenolic hydroxyl-containing reducing agent.It is possible to in situ form AuNPs to produce the composites with enhanced mimetic enzyme catalytic activity.In this study,tannic acid was first immobilized on the surface of MOGs?Fe? by complexation of phenolic hydroxyl groups in tannic acid with Fe??? on the surface of MOGs?Fe?.Then,this tannic acid on the surface of MOGs?Fe? was used as a reducing agent to in situ reduce the chloroauric acid to form AuNPs.The obtained AuNPs/MOGs?Fe? composites exhibited synergistically enhanced mimicking peroxidase-like activity,which can catalyze the decomposition of H₂O₂ to generate multiple reactive oxygen species to oxidize luminol and produce enhanced chemiluminescence signals in the presence of H₂O₂.Based on that organophosphorus pesticide can irreversibly inhibit the enzymatic activity of AChE,thus inhibiting the production of H₂O₂ and reduce the chemiluminescence intensity,a chemiluminescence analysis method for sensitive detection of organophosphorus pesticides was established.Under the optimal experimental conditions,this new developed method showed good linearity in the range from 5 nM to 800 nM with the detection limit of 1 nM.3.The preparation of Ru-MOGs with double NADH and horseradish peroxidase activity and their application in the detection of glucose.Novel 3D ruthenium-based metal-organic gels?Ru-MOGs?consisting of 1,10-phenanthroline-2,9-dicarboxylic acid as the ligand and ruthenium(Ru³⁺) as the central ion with fibrillar network structure have successfully synthesized using a facile one-step strategy at room temperature.After the freeze-drying treatment to remove the encapsulated solvent to expose the porous structure,the resulting Ru-MOGs possess intrinsic mimic dual-peroxidase-like activies,which can not only mimic horseradish peroxidase functionalities toward the oxidation of dopamine by H₂O₂ in acidic media and the H₂O₂-catalyzed luminol chemiluminescence in alkaline environment,but also display excellent NADH peroxidase-like catalytic activity toward the oxidation of NADH to the biologically active NAD⁺cofactor.Enzymatic kinetic analysis reveals that Ru-MOGs catalyst is an effective heterogeneous catalyst with exceptionally high catalysis velocity,binding affinities and high catalytic efficiency.Furthermore,as a proof-of-concept,a chemiluminescence analysis method for glucose detection was constructed since glucose could be aerobic oxidized to produce H₂O₂ under the catalysis of glucose oxidase.