Optical Propetries And Biological Applications Of Infared Photosensitive Gold Nanorods And Rare Earth Upconversion Luminescent Nanoparticles

The infared functional nanomaterials such as noble metal and rare earth dopedupconversion luminescent nanoparticles have shown attractive prospects in tumortarget therapy, living fluorescence imaging, sensing and other biomedical applications.However, there are still existing some obstacles and limitations in practice. Strongsurface plasmon resonance properties of gold nanorods in near infrared region makeeffective light-heat conversion, which make gold nanorods being ideal photosensitivematerials in tumor hyperthermia. However, surface properties of gold nanorodsinfluence their stability, especially, the targeting function in tumor therapy in complexenvironment. With the advantages of deep penetration and low backgroundfluorescence, Rare-earth infared-visible upconversion luminescent nanoparticles haveapplied in living imaging, but the low fluorescence conversion efficiency makesvisible light emission be difficult to be detected in vivo imaging. To solve the aboveproblems, based on gold nanorods and rare earth doped upconversion luminescentnanoparticles in this paper, one hand, we modified gold nanorods with PAA andconjugated targeting peptide on the rods surface, and the prepared targetingconjugates were applied in selective photothermal thrapy; then, we discussed theinteraction between glutathione modified gold nanorods and protein, and studied thetargeting imaging and photothermal therapy of folic acid and rhodamine B conjugatedgold nanorods; the other hand, we compared the synthesis and optical properties ofNaLuF₄:Yb³⁺, Er³⁺and NaYF₄:Yb³⁺, Er³⁺and confirmed the dependencies ofupconversion luminescence with substrate composition, crystal structure and size;based on above, we chose the easily controlled NaYF₄:Yb, Tm as upconversionluminescence nanocrystalline and detected adivin concentration through fluorescentquenching between gold nanorods and NaYF₄:Yb, Tm. The results we obtained were shown as follows:[1] We prepared PAA modified gold nanorods （GNRs） through Layer-by-Layermethod and observed the higher weight of PAA modified GNRs with betterbiocompatibility and non-cytotoxity. And then we obtained targeting peptide throughphase display peptide library technology, which could specific interact with HER2positive cells. Finally, we obtained selective photothermal therapy with targetingpeptide functionalized GNRs.[2] We prepared glutathione modified gold nanorods （GSSG-GNRs） throughrobust Au-S bond information and demonstrated the GSSG-GNRs were stable inaqueous solution over a broad range of pH and high ionic strength values.Importantly, the glutathione coating greatly reduces non-specific protein adsorptionon GNRs. Then we obtained selective targeting imaging and photothermal therapywith folic acid and rhodamine B functionalized GNRs.[3] We synthesized NaREF₄:Yb³⁺, Er³⁺（RE=Lu, Y） at different reactiontemperatures by the solvothermal method. In the NaREF₄preparation process, whenthe Y3+was replaced by Lu3+, NaLuF₄nanocrystals grew faster and were easier toform a cubic phase structure. The fluorescence intensity change of NaLuF₄andNaYF₄was closely related with the size and structure of the nanocrystalline and hadlittle to do with Lu/Y-matrix. On emphasis, we gave a universal explanation on thephase, and size dependent color-tuning behaviors of NaREF₄:Yb³⁺, Er³⁺（RE=Y, Lu）.[4] We prepared hydrophilic PEI coating NaYF₄: Yb, Tm nanoparticles throughhydrothermal method. The biotion and adivin molecules were conjugated to PEIcoating NaYF₄and PAH modified gold nanorods through covalent bonds,respectively. Adivin concentration was detected based on fluorescence resonanceenergy transfer （FRET） between upconversion nanopaticles and gold nanorods. Andwe provided a novel near-infared responsive sensor system.