Investigation On High-performance Electrochemical Sensing Methods Based On Porphyrin-based Two-dimensional Metalorganic Framework Nanomaterials

Metal-organic frameworks（MOFs）have been widely used in high-performance electrochemical sensing due to the outstanding advantages such as large specific surface area,ultra-high porosity,and abundant active sites.In this dissertation,electrochemical sensors based on seven porphyrin-based two-dimensional MOFs nanomaterials were constructed,and novel methods for detecting H₂O₂,DA,MNZ,LEV,TC,BPA and Pb²⁺were established.This dissertation can enrich the principles and methods of electrochemical sensing,and also broaden the application scope of MOFs.The dissertation was divided into three chapters;the main contributions of the author are as follows:1.Electrochemical sensing methods based on 2D MOFs and their derived nanomaterialsElectrochemical sensing methods for H₂O₂,DA,MNZ,LEV,TC based on Ag NPs/Cu-TCPP,Au Cu/PPy/Cu-TCPP,Co_xZn_100-x-TCPP and Cu NPs/Cu-TCPP were constructed.The H₂O₂electrochemical sensing method constructed based on Ag NPs/Cu-TCPP showed a linear range of 3.70μmol·L^-1-5.80 mmol·L^-1,a sensitivity of 21.6μA(mmol·L^-1)^-1 cm^-2,and a detection limit of 1.2μmol·L^-1;The H₂O₂ electrochemical sensing method based on Au Cu/PPy/Cu-TCPP showed a linear range of 7.10μmol·L^-1-24.10 mmol·L^-1,a sensitivity of 35.0μA(mmol·L^-1)^-1 cm^-2,a detection limit of 7 nmol·L^-1;The DA electrochemical sensing method based on Co₂₅Zn₇₅-TCPP has a linear range of 5.00 nmol·L^-1-177.80μmol·L^-1 and a detection limit of 2 nmol·L^-1;The TC electrochemical sensing method constructed based on Cu NPs/Cu-TCPP showed a linear range of 0.90μmol·L^-1-888.90μmol·L^-1 and a detection limit of 0.3μmol·L^-1.Compared with the two H₂O₂ sensing methods,the sensitivity of the sensing method based on Au Cu/PPy/Cu-TCPP was increased by 1.6 times,and the detection limit was reduced by 179.1 times;Compared with the related electrochemical sensing methods,the detection limit of the sensing method based on Au Cu/PPy/Cu-TCPP was reduced by an order of magnitude;the electrochemical sensing method based on Co₂₅Zn₇₅-TCPP exhibited excellent selectivity,and the linear range was expanded by 1.8 times;The sensing method based on Cu NPs/Cu-TCPP exhibited the advantages of wide linear range and low detection limit for the detection of trace levels of LEV,MNZ,and TC in honey,milk and serum.2.Electrochemical biosensing methods based on two-dimensional MOFs combined with enzymes and DNA mimetic enzymesA BPA electrochemical biosensing method based on Tyr@Cu-TCPP was constructed.Studies have shown that Cu-TCPP can not only assemble a large amount of Tyr,but also effectively maintain its structural and biological activity,enabling Tyr@Cu-TCPP to exhibit significantly improved thermal stability,acid/base tolerance,and long-term storage stability.In addition,theπ-πstacking between Cu-TCPP and BPA was beneficial to the enrichment of BPA on the electrode surface.The sensing method has a linear range of 3.50 nmol·L^-1-18.90μmol·L^-1 for the determination of BPA with a detection limit of 1 nmol·L^-1.Compared with related studies,this sensing method exhibited excellent stability and specificity for BPA determination,with an 18.3-fold wider linear range.An electrochemical biosensing method for H₂O₂ based on G4-hemin/Cu-TCPP nanocomposites was constructed.Studies have shown that the synergistic catalysis of Cu-TCPP and G-quadruplex-hemin enables the method to exhibit a wide linear range:0.080μmol·L^-1-0.11 m mol·L^-1,0.11 mmol·L^-1-0.91 mmol·L^-1 and 0.91 mmol·L^-1-8.10 mmol·L^-1,the corresponding sensitivities were 2315.9,301.0,and 65.7μA(mmol·L^-1)^-1 cm^-2,respectively,with a detection limit of 0.03μmol·L^-1.Compared with related sensing methods,the detection limit of this method was reduced by 23.3 times and the sensitivity was increased by 14.8 times.Using G-quadruplex-hemin/Cu-TCPP combined with DNA nanomotor,an electrochemical biosensing method for indirect cycling detection of Pb²⁺was constructed.The research showed that using five sensing electrodes to detect 0.50μmol·L^-1 Pb²⁺for 20 cycles,the detection results can still maintain 88.3-93.5%of the initial detection results;The linear range for the determination of Pb²⁺was 5.00 nmol·L^-1-5.00μmol·L^-1,and the detection limit was 2 nmol·L^-1.Compared with related studies,this method has the advantages of 15.6 times wider linear range,1.8 times lower detection limit,and self-cleaning of electrode surface.