Construction Of High Efficient Electrochemical/Fluorescent Biosensor Based On Electrocatalytic Activity And Molecular Recognition Of MOFs

Metal-organic frameworks(MOFs),as a new multifunctional material,have attracted great attention in the field of electrochemical biosensing and fluorescence biosensing.On the one hand,MOFs are rich in catalytic active sites.Using MOFs as signal amplification materials to construct the biosensing platform can effectively improve the sensitivity of the biosensor.On the other hand,MOFs exhibit the diversity of components,and diversified metal ions and organic ligands endow the functions of MOFs with controllability.When MOFs as molecular recognition units and are in contact with target molecules,the interaction between the two will cause a specific response of MOFs,thereby achieving molecular recognition and improving the selectivity of the biosensor.Based on improving the sensitivity and selectivity of biosensors,this thesis focuses on regulating the electrocatalytic activity and molecular recognition function of MOFs,so as to construct high-efficiency electrochemical/fluorescent biosensors for trace detection of biomolecules.The main research contents of this project can be outlined as follows:1.Rare Co/Fe-MOFs exhibiting high catalytic activity in electrochemical aptasensors for ultrasensitive detection of ochratoxin A.As electrocatalysts,MOFs can effectively promote the electron transfer efficiency of the electron mediator,thereby enhancing the electrochemical signal to improve the sensitivity of the biosensor.This work explored the relationship between the substrate-free electrochemical catalytic abilities of three Co/Fe-MOFs for the dye molecule thionine,as well as the relationship between the catalytic ability and the coordination mode and different ligands.Furthermore,NH₂-Co-MOF possesses the best catalytic performance was used as the signal amplification material,and then combined with biological amplification strategy to achieve multiple signal enhancements.The constructed electrochemical aptasensor realized the ultra-sensitive detection of ochratoxin A.2.Size/morphology controllable NH₂-Ni-MOF electrocatalyst and DNA walker for the detection of C-reactive protein.The regulation of size and morphology is an effective way to improve the electrocatalytic activity of MOFs.Based on the structural modification of MOFs,a series of NH₂-Ni-MOFs were synthesized and their electrochemical catalytic performances were discussed.Then incorporated a new emerging enzymatic cleavage powered DNA walker for dual signal amplification.The constructed electrochemical aptasensor showed excellent performance in the detection of C-reactive protein.This strategy significantly improved the sensitivity of the biosensor and provided a theoretical basis for the regulation of the electrocatalytic activity of MOFs.3.Construction of an ultra-sensitive fluorescent biosensor based on the highly selective recognition of adenosine triphosphate by ZIF-67.Effective molecular recognition is the best way to improve the selectivity of biosensors.This study found that ZIF-67 possessed ultra-high selectivity for recognizing adenosine triphosphate(ATP).After analyzing the structure and metal valence of ZIF-67,and further verifying the specific binding of ZIF-67 to ATP with the help of isothermal titration calorimetry.ZIF-67 can not only distinguish ATP from other nucleoside triphosphates,but also possess desireable selectivity than aptasensors.4.A sensor array based on DNA-wrapped bimetallic zeolitic imidazolate frameworks for detection of ATP hydrolysis productsMetal substitution is an effective method to adjust the composition and molecular recognition performance of MOFs.In this work,a series of bimetallic M/ZIF-8(M=Ni,Mn,Cu)were prepared,and the molecular recognition characteristics of ZIFs with different metal centers were studied.Based on this,a new type of bimetallic ZIFs fluorescence sensor array was designed to detect ATP hydrolysis products.This work also found that Cu/ZIF-8 showed high selectivity in the recognition of pyrophosphate.This strategy will provide a new idea for developing highly specific molecular recognition units to improve the selectivity of biosensors.5.Homobimetallic Co Zn-ZIFs:guanosine triphosphate sensing and sensor array for nucleoside triphosphates discrimination.Bimetallic ZIFs provided more possibilities for the regulation of the molecular recognition function.Therefore,a series of homogenous bimetallic Co_xZn_100-x-ZIFs(x=0?100)was synthesized by adjusting the ratio of Co and Zn,and their recognition characteristics for a variety of phosphate-containing molecules were investigated.Based on the different affinity of various Co Zn-ZIFs to different nucleoside triphosphates(NTPs),a highly sensitive ZIF fluorescence sensor array was designed for the identification and differential detection of NTPs.In addition,Co₅₀Zn₅₀-ZIF also showed the ability of specifical recognizing GTP.This method further expands the application of MOFs as molecular recognition units in sensor arrays.