title: A General Strategy for Ligand Exchange on Upconversion Nanoparticles.
abstract: Lanthanide-doped upconversion nanoparticles with a suitable surface coating are appealing for biomedical applications. Because high-quality upconversion nanoparticles are typically prepared in an organic solvent and passivated by hydrophobic oleate ligands, a convenient and reliable method for the surface modification of upconversion nanoparticles is thus highly desired to satisfy downstream biological investigations. In this work, we describe a facile and versatile strategy for displacing native oleate ligands on upconversion nanoparticles with a diversity of hydrophilic molecules. The ligand-exchange procedure involves the removal of original oleate ligands followed by the attachment of new ligands in a separate step. The successful coating of relevant ligands was confirmed by Fourier transform infrared spectroscopy, thermogravimetry analysis, and ζ-potential measurement. The surface-modified nanoparticles display high stability and good biocompatibility, as revealed by electron microscopy, photoluminescence spectroscopy, and cytotoxicity assessment. Our study demonstrates that functional biomolecules such as biotin can be directly immobilized on the nanoparticle surface using this approach for the quick and effective detection of streptavidin.
authors.forename: Wei
authors.initials: W
authors.lastname: Kong
authors.forename: Tianying
authors.initials: T
authors.lastname: Sun
authors.forename: Bing
authors.initials: B
authors.lastname: Chen
authors.forename: Xian
authors.initials: X
authors.lastname: Chen
authors.forename: Fujin
authors.initials: F
authors.lastname: Ai
authors.forename: Xiaoyue
authors.initials: X
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Modern Optical Instrumentation, Zhejiang University , Hangzhou 310027, China.
authors.forename: Mingyu
authors.initials: M
authors.lastname: Li
authors.forename: Wenjun
authors.initials: W
authors.lastname: Zhang
authors.forename: Guangyu
authors.initials: G
authors.lastname: Zhu
authors.affiliation: City Universities of Hong Kong Shenzhen Research Institute , Shenzhen 518057, China.
authors.forename: Feng
authors.identifier: http://orcid.org/0000-0001-9471-4386
authors.initials: F
authors.lastname: Wang
mesh_terms: D000072283:A549 Cells; D000180:Acrylic Resins / Q000737:chemistry*; D002232:Carbocyanines / Q000737:chemistry; D005459:Fluorides / Q000737:chemistry / Q000633:toxicity; D006801:Humans; D008024:Ligands; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D009829:Oleic Acids / Q000737:chemistry*; D019809:Streptavidin / Q000737:chemistry; D015019:Yttrium / Q000737:chemistry / Q000633:toxicity
chemical_list: D000180:Acrylic Resins; D002232:Carbocyanines; D008024:Ligands; D009829:Oleic Acids; C089187:cyanine dye 3; C525362:sodium yttriumtetrafluoride; C006903:carbopol 940; D015019:Yttrium; D019809:Streptavidin; D005459:Fluorides