Synthesis Of Covalent Organic Framework Composite Materials And Their Applications In The Detection Of Biomarkers

As two-dimensional or three-dimensional crystalline porous polymers,covalent-organic frameworks(COFs)are formed by the condensation reaction of organic ligands.Their stable structure,high specific surface area,large porosity,high charge carrier mobility and other physical and chemical properties allow their wide applications in the fields of gas adsorption and separation,chemical sensing,photocatalysis and energy storage.In this paper,three kinds of COFs and composites were synthesized and further explored as electrochemical(EC)and photoelectrochemical(PEC)biosensors for the detection of biologically active molecule and biomarkers.This paper mainly includes the following aspects:Firstly,the porphyrin-based covalent organic framework(p-COF)was synthesized using5,10,15,20-tetrakis(4-aldehyde benzene)-21 H,23H-porphyrin and 5,5’-diamino-2,2’-bipyridine as linking ligands.In light of the highly conjugated π-electron macrocycles of porphyrin ligands and electroactive bipyridine moieties,the p-COF-based electrochemical(EC)and photoelectrochemical(PEC)sensor showed excellent electrochemical activity and photoactivity,good catalytic performance toward biologically active molecule nitric oxide(NO),and exhibited a low limitation of detection(LOD)of 17.3 n M and 71.2 n M,respectively.The developed p-COF-based sensor also showed excellent selectivity,good stability and reproducibility,as well as good approvability for detecting NO from the living cancer cells.Secondly,a novel metal-copper phthalocyanine-based covalent-organic framework(Cu TAPc-MCOF)doped with silver nanoparticles(denoted as Cu TAPc-MCOF@Ag NPs)was developed.Cu TAPc-MCOF was synthesized using Cu(II)4′,4′′,4′′′,4′′′′-tetra-amine phthalocyanine(Cu TAPc)and 2,9-bis[p-(formyl)phenyl]-1,10-phenanthroline as building blocks through the Schiff base condensation reaction.Ag NPs can boost the electrocatalytic ability and improve the biocompatibility of the Cu TAPc-MCOF.The Cu TAPcMCOF@Ag NPs-based EC sensor showed a low detection limit of 12.6 n M within the linear concentration range of 0.18 μM to 17.1 μM toward NO,together with excellent selectivity,high reproducibility and repeatability,and good stability.Cu TAPc-MCOF@Ag NPs composite illustrated superior biocompatibility and electrocatalytic activity,and showed potential application in the detection of NO released from living cancer cells.Finally,the pre-synthesized elliptical Cu-MOF were served as the template and introduced into the preparation system of Cu TAPc-COF to synthesize Cu-MOF@Cu TAPc-COF composite materials.Then it was employed as a sensitive layer for immobilization of human immunodeficiency virus(HIV-1)probe DNA to construct EC and PEC biosensing platforms for the detection of HIV-1 DNA.EC and PEC measurements showed that the CuMOF@Cu TAPc-COF-based biosensor exhibited low LODs of 0.18 and 0.02 f M in the concentration range of 1 f M ～ 1 n M toward HIV-1 DNA.The real samples test showed that the detected HIV-1 DNA in human serum had good consistency with the real concentration,which provides a new dual-mode biosensing platform for the detection of HIV-1 DNA.This work provides new ideas for the construction of COFs-based electrochemical/photoelectrochemical biosensors,and further expands the potential applications of COFs materials.