Photothermal Detection of Circulating Tumor Cells Using Programmable Self-assembly of Enzyme-embedded DNA Nanoflowers

KeyWord:rolling circle amplification  ?DNA nanoflowers  ?photothermal biosensor  ?circulating tumor cells  ?aptamer

Abstract:

      DNA nanotechnology has attracted a broad research interest in biosening field£¬in which various functional two- or three-dimensional DNA nanostructures have been constructed£®Rolling circle amplification£¨RCA£© as an isothermal amplification technique has provided a new way for the design and self-assembly of DNA nanomaterials£®Herein£¬the horseradish peroxidase£¨HRP£©-embedded DNA nanoflowers£¨HRP@DNFs£© are one-pot synthesized by RCA£¬which are further applied to the fabrication of photothermal biosensor for highly sensitive and selective detection of circulating tumor cells£¨CTCs£© in hepatocellular carcinomas£¨HCCs£© based on dual-aptamer recognition. After encapsulation of HRP into DNFs£¬the catalytic activity of HRP is significantly enhanced due to the formation of highly ordered and hydrogen-bonded water environment£®For HCCs detection£¬the aptamer TLS11a that can specifically recognize the HepG2 HCCs is designed in DNFs as the signal amplification labels£¬while the EpCAM aptamer-modified magnetic beads£¨EpCAM-MBs£© are prepared as the carrieres to capture HepG2 cells£®In the presence of HepG2£¬the sandwich structure of MBs/HepG2/HRP@DNFs is formed via specific dual-aptamer recognition. After magnetic separation and addition of 3£¬3'£¬5£¬5'-tetramethylbenzidine£¨TMB£© and H2O2 into the system£¬the HRP@DNFs can catalyze the oxidation of TMB£®Upon irradiated by 808 nm infrared laser£¬a strong photothermal conversion effect is produced by oxidized TMB£¬resulting in the photothermal detection of HepG2 cells with high sensitivity and specificity£®Overall£¬the proposed strategy for one-pot self-assembly of enzyme-embedded DNA nanoflowers possesses a great potential in early diagnosis of diseases£¬especially cancers£®