title: Facile synthesis of 5 nm NaYF₄:Yb/Er nanoparticles for targeted upconversion imaging of cancer cells.
abstract: 5nm intense green emission NaYF4:Yb/Er upconversion nanoparticles (UCNPs) with pure β phase was synthesized with a simple "green" strategy for the first time. Traditional organic solvothermal method is often applied to prepare the high-quality and uniform UCNPs, but the preparation of lanthanide-oleate complexes is laborious as heating and multistep post-treatment for purification are often required. The water-alcohols solvothermal method is environmentally friendly, but the fabricated UCNPs have big size, poor biocompatibility and high cytotoxicity, which limited their application for cell imaging. Herein, NaYF4:Yb/Er UCNPs were prepared with rare-earth nitrates RE(NO3)3 (RE=Y0.80 Yb0.18 Er0.02) as precursors and diethylene glycol (DEG)/ethylene glycol (EG)/water as the solvent. A facile green solvothermal method with the temperature being controlled at 300°C was developed. The as-prepared NaYF4:Yb/Er UCNPs were characterized and were found to have enhanced UC emission and controllable particle size. The as-prepared UCNPs were further functionalized via folic acid coating for the targeted imaging and improved bio- compatibility. It was made the UCNPs potential for upconversion bioimaging of living cells by the strong upconversion luminescence, the excellent biocompatibility, and the super-small size. The good colloidal stability and low cell cytotoxicity of the as-prepared UCNPs and the developed synthesis protocol might advance both the fields of UCNPs and biomolecule-based nanotechnology for future studies.
authors.affiliation: Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecule, College of Chemistry, Tianjin Normal University, 393 Binshui West Road, Tianjin 300387, PR China; Tianjin Environmental Protection Technical Development Center, 17 Fukang Road, Tianjin 300191, PR China.
authors.forename: Yueli
authors.initials: Y
authors.lastname: Hu
authors.affiliation: College of Laboratory Medicine, Tianjin Medical University, 1 Guangdong Road, Tianjin 300203, PR China.
authors.forename: Boyue
authors.initials: B
authors.lastname: Wu
authors.affiliation: Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecule, College of Chemistry, Tianjin Normal University, 393 Binshui West Road, Tianjin 300387, PR China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Jin
authors.affiliation: College of Laboratory Medicine, Tianjin Medical University, 1 Guangdong Road, Tianjin 300203, PR China.
authors.forename: Xueyuan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecule, College of Chemistry, Tianjin Normal University, 393 Binshui West Road, Tianjin 300387, PR China. Electronic address: nkliyan398@gmail.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecule, College of Chemistry, Tianjin Normal University, 393 Binshui West Road, Tianjin 300387, PR China.
authors.forename: Yuxiu
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecule, College of Chemistry, Tianjin Normal University, 393 Binshui West Road, Tianjin 300387, PR China.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Huo
authors.affiliation: Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecule, College of Chemistry, Tianjin Normal University, 393 Binshui West Road, Tianjin 300387, PR China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Zhao
mesh_terms: D016475:3T3 Cells; D000818:Animals; D060326:Chemistry Techniques, Synthetic; D004871:Erbium / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry*; D005492:Folic Acid / Q000737:chemistry; D055772:Green Chemistry Technology; D006367:HeLa Cells; D006801:Humans; D049449:Luminescence; D051379:Mice; D057054:Molecular Imaging / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D036103:Nanotechnology; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013696:Temperature; D015018:Ytterbium / Q000737:chemistry*; D015019:Yttrium / Q000737:chemistry*
chemical_list: D012997:Solvents; C525362:sodium yttriumtetrafluoride; D011092:Polyethylene Glycols; D015019:Yttrium; D004871:Erbium; D005492:Folic Acid; D015018:Ytterbium; D005459:Fluorides
keywords: NaYF(4):Yb/Er; Solvothermal method; Targeting cell imaging; Upconversion nanoparticles