Research On Bioanalysis Based On DNA Nanotechnology

DNA nanotechnology has been widely used in biological analysis because it has many advantages,for example,it is easy to be synthesized and modified,and it also has high biocompatibility.But in the complex biological environment,the poor cell permeation,instability caused by nuclease degradation,weak resistance to nucleic acid crosstalk and some inherent defects cause the poor probe permeability,the high background signal or the false positive signal.As a result,the constructed nucleic acid biosensor has a low sensitivity and the low accuracy of detection results.The low abundance biomarkers are also hard to be detected.To address these challenges,we used framework nucleic acid(FNA)-based DNA circuits for intracellular logical computation and mRNA imaging.By rational design,such FNA-based DNA circuits can be directly delivered into cells.The pendant duplex DNA at one vertex of FNA was designed as a gate for four-way strand exchange,thus minimizing crosstalk with intracellular DNA.We demonstrated that FNA-based circuits enable to implement both in vitro and in vivo logic computation,including OR and AND logic gates.Moreover,in situ mRNA imaging can be achieved by utilizing natural mRNA as scaffolds to combine with multiple FNA-based gates to improve the enhanced signal-to-background ratio.In principle,this method solves the shortcomings of the poor cell penetration of DNA molecules requiring transfection reagents to enter the cell,the easy degradation of DNA by intracellular nucleases and the interference of chain replacement reaction by other nucleic acids,and it also provides a new idea for the detection of low abundance biomarkers of diseases.We hope that this FNA-based circuit can be applied for disease diagnosis,facilitating the development of biomedicine.Finally,we developed a biosensor for ATP detection in combination of dynamically adjustable DNA tweezer with highly specific aptamer.DNA tweezer was composed of three strands that can be converted into close state from open state after binding with nucleic acid aptamer.In the presence of target ATP,DNA tweezer can binds with the aptamer.Once the target molecule ATP is present,it specifically binds the aptamer and switches the DNA tweezer from off to on.Based on the changed state,ATP can be detected by monitoring the fluorescence changes.This process provides a new entry point for the in situ detection of ATP in cells,which is expected to promote the development of the application of ATP molecule as a biomarker for related biochemical research and clinical diagnosis.