title: High-Contrast Visualization of Upconversion Luminescence in Mice Using Time-Gating Approach.
abstract: Optical imaging through the near-infrared (NIR) window provides deep penetration of light up to several centimeters into biological tissues. Capable of emitting 800 nm luminescence under 980 nm illumination, the recently developed upconversion nanoparticles (UCNPs) suggest a promising optical contrast agent for in vivo bioimaging. However, presently they require high-power lasers to excite when applied to small animals, leading to significant scattering background that limits the detection sensitivity as well as a detrimental thermal effect. In this work, we show that the time-gating approach implementing pulsed illumination from a NIR diode laser and time-delayed imaging synchronized via an optical chopper offers detection sensitivity more than 1 order of magnitude higher than the conventional approach using optical band-pass filters (S/N, 47321/6353 vs 5339/58), when imaging UCNPs injected into Kunming mice. The pulsed laser illumination (70 μs ON in 200 μs period) also reduces the overall thermal accumulation to 35% of that under the continuous-wave mode. Technical details are given on setting up the time-gating unit comprising an optical chopper, a pinhole, and a microscopy eyepiece. Being generally compatible with any camera, this provides a convenient and low cost solution to NIR animal imaging using UCNPs as well as other luminescent probes.
authors.affiliation: Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University , Sydney, New South Wales 2109, Australia.
authors.forename: Xianlin
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Department of Chemistry & Institutes of Biomedical Sciences & State Key Laboratory of Molecular Engineering of Polymers, Fudan University , Shanghai, 200433, PR China.
authors.forename: Xingjun
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University , Sydney, New South Wales 2109, Australia.
authors.forename: Yiqing
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University , Sydney, New South Wales 2109, Australia.|Institute for Photonics and Advanced Sensing and School of Physical Sciences, University of Adelaide , Adelaide, South Australia 5005, Australia.
authors.forename: Jiangbo
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Chemistry & Institutes of Biomedical Sciences & State Key Laboratory of Molecular Engineering of Polymers, Fudan University , Shanghai, 200433, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.affiliation: Nanochemistry Research Institute, Department of Chemistry, Curtin University , Perth, Western Australia 6102, Australia.|Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology Sydney , Sydney, New South Wales 2007, Australia.
authors.forename: Guohua
authors.initials: G
authors.lastname: Jia
authors.affiliation: Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University , Sydney, New South Wales 2109, Australia.|Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology Sydney , Sydney, New South Wales 2007, Australia.
authors.forename: Fan
authors.initials: F
authors.lastname: Wang
authors.affiliation: Department of Chemistry & Institutes of Biomedical Sciences & State Key Laboratory of Molecular Engineering of Polymers, Fudan University , Shanghai, 200433, PR China.
authors.forename: Fuyou
authors.initials: F
authors.lastname: Li
authors.affiliation: Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University , Sydney, New South Wales 2109, Australia.|Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology Sydney , Sydney, New South Wales 2007, Australia.
authors.forename: Dayong
authors.initials: D
authors.lastname: Jin
mesh_terms: D000818:Animals; D007259:Infrared Rays; D007834:Lasers; D049449:Luminescence; D049408:Luminescent Agents / Q000008:administration & dosage / Q000737:chemistry; D051379:Mice; D008815:Mice, Inbred Strains; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry; D013696:Temperature; D013997:Time Factors
chemical_list: D049408:Luminescent Agents