title: Designing Upconversion Nanocrystals Capable of 745 nm Sensitization and 803 nm Emission for Deep-Tissue Imaging.
abstract: A crystal design strategy is described that generates hexagonal-phased NaYF4 :Nd/Yb@NaYF4 :Yb/Tm luminescent nanocrystals with the ability to emit light at 803 nm when illuminated at 745 nm. This is accomplished by taking advantage of the large absorption cross-section of Nd(3+) between 720 and 760 nm plus efficient spatial energy transfer and migration through Nd(3+) →Yb(3+) →Yb(3+) →Tm(3+) . Mechanistic investigations suggest that a cascaded two-photon energy transfer upconversion process underlies the emission mechanism. This protocol enables deep-tissue imaging to be achieved while mitigating the attenuation effect associated with the visible emission and the overheating constraint imposed by conventional 980 nm excitation.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
authors.forename: Liangliang
authors.initials: L
authors.lastname: Liang
authors.affiliation: Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergistic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, P. R. China.
authors.forename: Xiaoji
authors.initials: X
authors.lastname: Xie
authors.affiliation: Singapore Institute of Neurotechnology (SINAPSE), Singapore, 117456, Singapore.
authors.forename: Daniel Teh Boon
authors.initials: DT
authors.lastname: Loong
authors.affiliation: Department of Orthopedic Surgery, National University of Singapore, Singapore 119228 (Singapore), Department of Biomedical Engineering, National University of Singapore, Singapore, 117583, Singapore. angelo.all@nuhs.edu.sg.
authors.forename: Angelo Homayoun
authors.initials: AH
authors.lastname: All
authors.affiliation: Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergistic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, P. R. China. iamlhuang@njtech.edu.cn.
authors.forename: Ling
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore. chmlx@nus.edu.sg.|Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Singapore, 138634, Singapore. chmlx@nus.edu.sg.
authors.forename: Xiaogang
authors.identifier: http://orcid.org/0000-0003-2517-5790
authors.initials: X
authors.lastname: Liu
mesh_terms: D021621:Imaging, Three-Dimensional / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*
keywords: doping; lanthanide; nanocrystals; optical window; overheating effects