New nanoplatforms based on UCNPs linking with polyhedral oligomeric silsesquioxane (POSS) for multimodal bioimagingElectronic supplementary information (ESI) available: Schematic illustration of the formation of POSS-UCNPs. TEM images of NaYF4:Yb,Tm and NaYF4:Yb,Tm@NaGdF4 nanoparticles in cyclohexane; the TEM image of POSS-UCNPs(Tm) in water. DLS of POSS-UCNPs(Tm) in water. The energy dispersive X-ray (EDX) spectrum of POSS-UCNPs(Er). XPS of POSS-UCNPs(Er); XPS of Si element. UCL spectra of POSS

• Main Authors: Ge, Xiaoqian, Dong, Liang, Sun, Lining, Song, Zhengmei, Wei, Ruoyan, Shi, Liyi, Chen, Haige
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c5nr00950b

A new and facile method was used to transfer upconversion luminescent nanoparticles from hydrophobic to hydrophilic using polyhedral oligomeric silsesquioxane (POSS) linking on the surface of upconversion nanoparticles. In comparison with the unmodified upconversion nanoparticles, the POSS modified upconversion nanoplatforms [POSS-UCNPs(Er), POSS-UCNPs(Tm)] displayed good monodispersion in water and exhibited good water-solubility, while their particle size did not change substantially. Due to the low cytotoxicity and good biocompatibility as determined by methyl thiazolyl tetrazolium (MTT) assay and histology and hematology analysis, the POSS modified upconversion nanoplatforms were successfully applied to upconversion luminescence imaging of living cells in vitro and nude mouse in vivo (upon excitation at 980 nm). In addition, the doped Gd 3+ ion endows the POSS-UCNPs with effective T 1 signal enhancement and the POSS-UCNPs were successfully applied to in vivo magnetic resonance imaging (MRI) for a Kunming mouse, which makes them potential MRI positive-contrast agents. More importantly, the corner organic groups of POSS can be easily modified, resulting in kinds of POSS-UCNPs with many potential applications. Therefore, the method and results may provide more exciting opportunities for multimodal bioimaging and multifunctional applications. POSS was used to transfer upconversion nanoparticles into hydrophilic. Benefitted from the low cytotoxicity and excellent biocompatibility, the obtained POSS-UCNPs have been successfully applied to cell, small animal and MR imagings.