Controllable DNA Functionalization And Self-assembly Of NIR-emitting Gold Nanoparticles

Thiolate-protected luminescent ultrasmall gold nanoparticles(AuNPs,d < 3.0 nm)become an emerging nanomaterial in environmental detection,drug loading,disease diagnosis and therapy by virtue of their tunable optical properties,ligand-oriented functionalization potentials and good biocompatibility.By regulating the protecting thiolated ligand,AuNPs can emit at a broad spectrum ranging from visible region to near infrared region.And when those AuNPs were functionalized with DNA,it would combine both the advantages of luminescent AuNPs and DNA,which could obtain new peculiarity by assembling into well-organized structure through Watson-Crick base pairing.In the traditional DNA functionalization,AuNPs with surface plasmonic resonance absorbance(SPR-AuNPs)were selected,which had sparse ligand layer and large size that provided convenience for DNA functionalization through ligand exchange method.But However,this similar ligand exchange strategy would be hardly adaptable to the ultrasmall thiolate-protected luminescent AuNPs with unique Au(0)core and Au(I)-S shell structures.Thus,to realize controllable DNA functionalization onto ultrasmall luminescent AuNPs,we tried a one-step synthesis and ligand exchange method by using phosphorothioates(ps)-modified DNA(psDNA)to as template to prepare DNA modified AuNPs and used them for the following self-assembly and cell targeted imaging.The results were listed below:By using the phosphorothioates(ps)-modified DNA(psDNA)as template and reductant,we had prepared ultrasmall 810 nm-emitting AuNPs(?1.7 nm)with discrete number of bioactive DNA(psDNA-AuNPs)through heating Au(I)-Glutathione complexes.The DNA valence of psDNA-AuNPs could be finely tuned to 1(V1)or 2(V2,Divalent)by regulating the ps number of psDNA,and the size of psDNA-AuNPs could be also regulated around 1.3-2.6 nm by the changing the ps number of psDNA.After that,we used the purified psDNA-AuNPs as building blocks to fabricate wellcontrolled one-dimensional assembly and cellular imaging probe through Watson-Crick base pairing.By hybridized with sgc8c aptamer(Apt-AuNPs),psDNA-AuNPs were be endowed with the ability to target PTK7 protein overexpressed in CCRF-CEM cells,which were soon confirmed effective in the significant enhancement of fluorescence observed in CCRF-CEM cells.Then,by incubated with 2,3 and 6 repeated sequence complementary to the binding domain of psDNA-AuNPs,purified V1-psDNA-AuNPs were organized into assembled nanostructures bearing discrete number of AuNPs.By regulating the concentration of complementary DNA template,we also studied the self-assembly and disassembly transformation process of them.In summary,the one-step fabrication of luminescent AuNPs bearing discrete number of DNA offer a new modification strategy for thiolate-protected luminescent AuNPs community,which also acted as an important bridge linking the luminescent AuNPs and DNA nanotechnology together,providing further application for luminescent AuNPs.These results provide ultrasmall luminescent AuNPs with brand-new controllable functionalization method,and will offer an effective nanoplatform for many downstream applications such as drug loading,disease diagnosis and therapy.