Detection Of Cancer Biomarkers And Specific Cleavage Of DNA Of Functional Nanotetrahedron

In this paper,the self-assembly of different kinds of nanomaterials based on DNA was studied.DNA could be used as the backbone to assemble different nanomaterials into tetrahedron structure and this assembly structure can achieve ultrasensitive detection of specific cancer biomarkers.If the nanomaterial with tetrahedron morphology was used to assemble with DNA,can not only achieve simultaneous changes in the morphology and properties of the material,but also can cut the DNA at a specific site.Make the nanomaterial enzyme functional in the assistance of circular polarized light.Firstly,aptamer sequences that can specifically recognize cancer biomarkers were used as assembly frameworks for nanomaterials.Gold and upconversion nanoparticles were assembled into tetrahedral structure as a kind of biosensor,who can specifically recognize the thrombin and prostate-specific antigen?PSA?at the same time and realized ultrasensitive detection of both targets at the same time using surface-enhanced Raman scattering?SERS?and fluorescence respectively.The higher the concentration of thrombin was,the lower the intensity of SERS was.PSA connected with the PSA aptamer leading to an increase in fluorescence intensity.The limit of detection of thrombin and PSA reached 5.7×10^-17 and3.2×10^-20 M,respectively.In addition,the pyramid also exhibited great target specificity.Lithium cadmium telluride?CdTe?nanoparticles modified with chiral cysteine ligand were synthesized.The material with truncated tetrahedral shape structure can self-assemble into rod-like nanocrystals with salmon sperm DNA illuminated under 405nm RCP/LCP.When the structural analogues of cysteine were used as ligands to synthesize chiral CdTe nanoparticles,they could not self-assemble into rod-like nanocrystals.Only the special configuration of cysteine can contact and bind with salmon sperm DNA.The DNA accelerated the transfer of electrons in the whole system,and eventually formed fluorescent Te-rich chiral nanorods.Through electrophoretic characterization and sequence analysis of the DNA in the solution after assembly of the above CdTe nanoparticles,chiral cysteine-modified cadmium telluride nanoparticles acted as a kind of restriction endonuclease and can specifically recognize double-stranded DNA which is more than 90 base pairs and selectively cut upon photonic excitation at the restriction site GAT?ATC??indicates the cleavage site?.Notably,our results demonstrated that cleavage activity originates from photoinduced reactive oxygen species.This site-specific cleavage was attributed to the affinity between the Cys-modified CdTe and the specific DNA conformation.