title: Multihydroxy dendritic upconversion nanoparticles with enhanced water dispersibility and surface functionality for bioimaging.
abstract: Upconversion nanoparticle (UCNP) as a new class of imaging agent is gaining prominence because of its unique optical properties. An ideal UCNP for bioimaging should simultaneously possess fine water dispersibility and favorable functional groups. In this paper, we present a simple but effective method to the synthesis of a UCNP-based nanohybrid bearing a multihydroxy hyperbranched polyglycerol (HPG) shell by the combination of a "grafting from" strategy with a ring-opening polymerization technique. The structure and morphology of the resulting UCNP-g-HPG nanohybrid were characterized in detail by Fourier transform infrared, (1)H NMR, thermogravimetric analysis, and transmission electron microscopy measurements. The results reveal that the amount of grafted HPG associated with the thickness of the HPG shell can be well tuned. UCNP-g-HPG shows high water dispersibility and strong and stable upconversion luminescence. On the basis of its numerous surface hydroxyl groups, UCNP-g-HPG can be tailored by a representative fluorescent dye rhodamine B to afford a UCNP-g-HPG-RB nanohybrid that simultaneously presents upconversion and downconversion luminescence. Preliminary biological studies demonstrate that UCNP-g-HPG shows low cytotoxicity, high luminescent contrast, and deep light penetration depth, posing promising potential for bioimaging applications.
authors.affiliation: Guangxi Ministry-Province Jointly-Constructed Cultivation Base for State Key Laboratory of Processing for Nonferrous Metal and Featured Materials, Key Laboratory of New Processing Technology for Nonferrous Metal and Materials (Ministry of Education), and College of Material Science and Engineering, Guilin University of Technology , Guilin 541004, P. R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhou
authors.forename: Benzhao
authors.initials: B
authors.lastname: He
authors.forename: Jiachang
authors.initials: J
authors.lastname: Huang
authors.forename: Zehong
authors.initials: Z
authors.lastname: Cheng
authors.forename: Xu
authors.initials: X
authors.lastname: Xu
authors.forename: Chun
authors.initials: C
authors.lastname: Wei
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D050091:Dendrimers / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D005990:Glycerol / Q000737:chemistry; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D018613:Microscopy, Confocal; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D010781:Photography; D011108:Polymers / Q000737:chemistry; D012235:Rhodamines / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry*
chemical_list: D050091:Dendrimers; D005456:Fluorescent Dyes; D011108:Polymers; D012235:Rhodamines; D014867:Water; C043941:polyglycerol; C029773:rhodamine B; D005990:Glycerol