title: Probing the Interior Crystal Quality in the Development of More Efficient and Smaller Upconversion Nanoparticles.
abstract: Optical biomedical imaging using luminescent nanoparticles as contrast agents prefers small size, as they can be used at high dosages and efficiently cleared from body. Reducing nanoparticle size is critical for the stability and specificity for the fluorescence nanoparticles probes for in vitro diagnostics and subcellular imaging. The development of smaller and brighter upconversion nanoparticles (UCNPs) is accordingly a goal for complex imaging in bioenvironments. At present, however, small UCNPs are reported to exhibit less emission intensity due to increased surface deactivation and decreased number of dopants. Here we show that smaller and more efficient UCNPs can be made by improving the interior crystal quality via controlling heating rate during synthesis. We further developed a unique quantitative method for optical characterizations on the single UCNPs with varied sizes and the corresponding shell passivated UCNPs, confirming that the internal crystal quality dominates the relative emission efficiency of the UCNPs.
authors.affiliation: Department of Engineering, Faculty of Science and Engineering, Macquarie University , Sydney, New South Wales 2109, Australia.|Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics, Macquarie University , Sydney, New South Wales 2109, Australia.
authors.forename: Chenshuo
authors.initials: C
authors.lastname: Ma
authors.affiliation: Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics, Macquarie University , Sydney, New South Wales 2109, Australia.|Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.|ARC Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL), Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.
authors.forename: Xiaoxue
authors.initials: X
authors.lastname: Xu
authors.affiliation: Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics, Macquarie University , Sydney, New South Wales 2109, Australia.|Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.|ARC Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL), Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.
authors.forename: Fan
authors.initials: F
authors.lastname: Wang
authors.affiliation: Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.|ARC Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL), Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.
authors.forename: Zhiguang
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.|ARC Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL), Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.
authors.forename: Shihui
authors.initials: S
authors.lastname: Wen
authors.affiliation: Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics, Macquarie University , Sydney, New South Wales 2109, Australia.|Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.|ARC Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL), Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.
authors.forename: Deming
authors.initials: D
authors.lastname: Liu
authors.affiliation: Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.|ARC Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL), Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Fang
authors.affiliation: Department of Engineering, Faculty of Science and Engineering, Macquarie University , Sydney, New South Wales 2109, Australia.
authors.forename: Candace I
authors.initials: CI
authors.lastname: Lang
authors.affiliation: Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics, Macquarie University , Sydney, New South Wales 2109, Australia.|Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.|ARC Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL), Faculty of Science, University of Technology , Sydney, New South Wales 2007, Australia.
authors.forename: Dayong
authors.initials: D
authors.lastname: Jin