Fabrication And Bioassy Application Of Two-photon DNA Nanosensing Conjugate Probe

Two-photon microscopic imaging technique is the use of near infrared (NIR)photons as the excitation source， with the long wavelength excitation and shortwavelength emission. The absorption process can effectively lower tissueauto-fluorescence and self-absorption, reduced photobleaching and photodamage.These features can not only improve the penetration depth of the organization andliving body (>500μm), at the same time also can extend the period of observation time.Because of its unique advantages, two-photon microscopy imaging has been widelyapplied in microscopic imaging of cells and tissues.Nanomaterials because of its small size effect and therefore have some uniqueproperties of light, heat, electricity, mechanics and so on. Due to its small size andgood biocompatibility, some nanomaterials can be used as an excellent vehicle to entercells, has been widely used in biological sensing. Based on the unique properties ofnanometer materials, combined with the special advantages of two-photon microscopyimaging, this thesis was focused on the following two aspects works:(1) Based on two-photon dye labeled aptamers(Aptamer-TPdye)/graphene oxide(GO)self-assembly and fluorescence resonance energy transfer, design a novel kind oftwo-photon probes for detecting adenosine triphosphate (ATP) in vitro and in vivo.Aptamer-TPdye due to π-π conjugate effect can be self-assembled onto GO thatformed GO/Aptamer-TPdye nanocomposites, the two-photon fluorescence group nearthe surface of the GO resulting fluorescence quenching. The binding force ofAptamer-TPdye combined with ATP is stronger than its with GO, so ATP cancompetitively combined with Aptamer-TPdye from the surface of GO, along with theconfiguration changes, fluorophore far away from GO, fluorescence recovery. Takeadvantages of using two-photon microscopy imaging, enabling sensitive detection ofATP in complex biological samples and successfully applied in the cell and in vivoimaging studies.(2) Based on DNA-TP template synthesis of gold/silver nano-alloys and efficientfluorescence resonance energy transfer principle, we develop a novel two-photonprobes of DNA template nanocomposite for cyanide ion (CN-) detectection. First,DNA-TP template synthesis of gold/silver nano-alloys. Due to the efficientfluorescence resonance energy transfer, the two-photon fluorescence is effectively quenched by the gold/silver nano-alloys. Due to the erosion of the CN-, the gold/silvernano-alloys nanoparticles became smaller, and finally falling off from the DNA-TPtemplate, resulting in the fluorescence recovery. This system realized the sensitivedetection of CN-.