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RGDS- and TAT-Conjugated Upconversion of NaYF4:Yb3+/Er3+&SiO2 Nanoparticles: In Vitro Human Epithelioid Cervix Carcinoma Cellular Uptake, Imaging, and Targeting
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文摘
Starting NaYF<sub>4sub>:Yb<sup>3+sup>/Er<sup>3+sup> nanoparticles with size tuned from 24 to 33 nm were prepared by high-temperature coprecipitation of lanthanide chlorides in high-boiling organic solvents. To enhance colloidal stability in aqueous medium, an aminosilica shell was introduced on the surface by hydrolysis and condensation of tetramethyl orthosilicate and (3-aminopropyl)trimethoxysilane using a reverse microemulsion technique; to form alkyne groups, reaction with 4-pentynoic acid followed. Finally, the cell adhesive and cell penetrating azidopentanoyl-GGGRGDSGGGY-NH<sub>2sub> (RGDS) and azidopentanoyl-GGGRKKRRQRRR-NH<sub>2sub> (TAT) peptides were conjugated to the upconversion particles via Cu(I)-catalyzed alkyne–azide cycloaddition. The concentrations of the peptides bound to the nanoparticle surfaces and amount of adsorbed residual Cu(I) catalyst were determined using an <sup>125sup>I-radiolabeled RGDS peptide and a <sup>64sup>Cu(I)-doped catalyst, respectively. Targeting and uptake of the RGDS- and TAT-conjugated NaYF<sub>4sub>:Yb<sup>3+sup>/Er<sup>3+sup>&SiO<sub>2sub> nanoparticles by human cervix carcinoma HeLa cells were monitored by confocal microscopy. RGDS-conjugated nanoparticle probes were mainly localized on the cell plasma membrane due to specific binding of the peptide to the corresponding integrins. In contrast, the TAT-conjugated nanoparticles were able to cross the cell membrane and accumulate in the cell cytoplasm. Thus, this new peptide bioconjugation approach supported both extra- and intracellular nanoparticle uptake, enabling targeting and imaging of the specific tumor phenotypes.

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