Functionalization of Covalent Organic Frameworks with DNA via Covalent Modification and the Application to Exosomes Detection

The functionalization of covalent organic frame-works (COFs) with biomacromolecules can extend their functions, which is the premise of their application in biomedical research. However, strategies to functionalize COFs with biomacromole-cules, which can ensure the stability in complex medium and minimize the undesired effects, are still lacking. In this work, we have proposed a strategy to functionalize COFs with DNA bycovalently linking DNA to the functional group on the COFsurface through Cu(I)-catalyzed azide/alkyne cycloaddition(CuAAC) reaction. The as-prepared DNA-functionalized COFs (DNA-COFs) can exhibit good hybridization ability and cargoloading ability; thus, we have designed a DNA-COF-based nanoprobe and then fabricated an electrochemical biosensor for the detection of exosomes. In this design, the functionalization with DNA enables COFs to recognize and capture exosomes, and the encapsulation of a large number of methylene blue (MB) in COFs facilitates signal amplification, which can enhance the sensitivity of the biosensor. Moreover, by simply replacing the oligonucleotide sequences, the strategy proposed here can generally be used to build different DNA-COFs with diverse functions for broader biomedical applications

Automated summary

In this study, we proposed a functionalization strategy for covalent organic frameworks (COFs) using DNA. The DNA-functionalized COFs exhibited good hybridization ability and cargo loading ability. Based on this, an electrochemical biosensor for the detection of exosomes was developed. The functionalized COFs enabled the recognition and capture of exosomes, while the encapsulation of methylene blue in the COFs enhanced the sensitivity of the biosensor.