title: Highly Enhanced Cooperative Upconversion Luminescence through Energy Transfer Optimization and Quenching Protection.
abstract: Upconversion luminescence nanomaterials have shown great potential in biological and physical applications because of their unique properties. However, limited research exists on the cooperative sensitization upconversion emission in Tb(3+) ions over Er(3+) ions and Tm(3+) ions because of its low efficiency. Herein, by optimizing the doping ratio of sensitizer and activator to maximize the utilization of the photon energy and introducing the CaF2 inert shell to shield sensitizer from quenchers, we synthesize ultrasmall NaYbF4:Tb@CaF2 nanoparticles with a significant enhancement (690-fold) in cooperative sensitization upconversion emission intensity, compared with the parent NaYbF4:Tb. The lifetime of Tb(3+) emission in NaYbF4:Tb@CaF2 nanoparticles is prolonged extensively to ∼3.5 ms. Furthermore, NaYbF4:Tb@CaF2 was applied in in vitro and in vivo bioimaging. The presented luminescence enhancement strategy provides cooperative sensitization upconversion with new opportunities for bioapplication.
authors.affiliation: Department of Chemistry & State Key Laboratory of Molecular Engineering of Polymers & Institute of Biomedicine Sciences & Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University , 220 Handan Road, Shanghai 200433, P. R. China.
authors.forename: Meng
authors.initials: M
authors.lastname: Xue
authors.affiliation: Department of Chemistry & State Key Laboratory of Molecular Engineering of Polymers & Institute of Biomedicine Sciences & Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University , 220 Handan Road, Shanghai 200433, P. R. China.
authors.forename: Xingjun
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Chemistry & State Key Laboratory of Molecular Engineering of Polymers & Institute of Biomedicine Sciences & Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University , 220 Handan Road, Shanghai 200433, P. R. China.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Qiu
authors.affiliation: Department of Chemistry & State Key Laboratory of Molecular Engineering of Polymers & Institute of Biomedicine Sciences & Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University , 220 Handan Road, Shanghai 200433, P. R. China.
authors.forename: Yuyang
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Department of Chemistry & State Key Laboratory of Molecular Engineering of Polymers & Institute of Biomedicine Sciences & Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University , 220 Handan Road, Shanghai 200433, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.affiliation: Department of Chemistry & State Key Laboratory of Molecular Engineering of Polymers & Institute of Biomedicine Sciences & Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University , 220 Handan Road, Shanghai 200433, P. R. China.
authors.forename: Fuyou
authors.initials: F
authors.lastname: Li
mesh_terms: D002124:Calcium Fluoride / Q000737:chemistry; D004735:Energy Transfer; D006367:HeLa Cells; D006801:Humans; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods*; D049329:Nanostructures / Q000737:chemistry*; D013725:Terbium / Q000737:chemistry*; D015018:Ytterbium / Q000737:chemistry*
chemical_list: D013725:Terbium; D015018:Ytterbium; D002124:Calcium Fluoride
keywords: CaF2 inert shell; bioimaging; cooperative upconversion luminescence; efficient Tb3+ emission; energy transfer optimization