Light-released DNA In Cells Based On Host-guest Interaction

Gene therapy has broad prospects in the biomedical and bio-organic science field,gene silencing also has important biological significance. The most critical issue ofgene therapy is how to successfully introduced exogenous nucleic acid chain into cells,as well as how to release it controlled and efficiently. Currently, the use ofnanomaterials as a load carrier has gained great success.This paper mainly studiedhow to release the exogenous nucleic acid controlled and efficiently in cells after itwas loaded into cells through the gold nanoparticles.At first, we studied light-regulated gene silencing based on host-guest interactionbetween cyclodextrins and azobenzene. We modified thiolated cyclodextrin on thesurface of gold nanoparticles and labeled the small molecules,azobenzene, in thetarget nucleic acid strand. Trans-azobenzene molecules can enter the cavity ofcyclodextrin, forming “DNA-AuNP” complex. The complex can enter into cells bythe biocompatible gold particles. The configuration of azobenzene was changed byUV irradiation making it get out of the cavity of cyclodextrin, which could achieverelease the target chain controlled and inhibit the expression of the green fluorescentprotein.Secondly, we studied released nucleic acid strands in cells quickly based on thesynergy effects of ferrocene. The binding constants of ferrocene with cyclodextrins ishigher an order of magnitude than the binding constants of azobenzene withcyclodextrin. Therefore, ferrocene will promote the releasing of azobenzene fromcyclodextrin. At the present of ferrocene, the light-induced releasing target standwould speed up.Finally, the studied the detection of silver ions by surface-enhanced Ramanspectroscopy based on triplex DNA stand. Single-strand DNA can dispersed goldparticles well,but triplex-strand can not dispersed gold nanoparticles. Silver ions andcytosine can form into a complex,“C-Ag+-C”. After adding silver ions into thesolution, the single-stranded and double-stranded combine to form triplex structurethrough silver ions, the gold nanoparticles would aggregate at high salt concentrations.We can detect it by means of SERS Raman, because rhodamine molecules (R6G) wereadsorbed on the surface of gold nanoparticles and there were "hot spot" when goldnanoparticles got aggregated to detect silver ions.