25 February 2016:
CNBP researchers have published a paper in the journal Analytical Chemistry titled, “High-contrast visualization of upconversion luminescence in mice using timegating approach.”
Authors: Xianlin Zheng, Xingjun Zhu, Yiqing Lu, Jiangbo Zhao, Wei Feng, Guohua Jia, Fan Wang, Fuyou Li and Dayong Jin.
Abstract: Optical imaging through the near-infrared (NIR) window provides deep penetration of light up to several centimetres 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 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 one order of magnitude higher than the conventional approach using optical band-pass filters (S/N: 47321/6353 vs. 5339/58), when imaging UNCPs injected into Kunming mice. The pulsed laser illumination (70μs 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 cameras, this provides a convenient and low cost solution to NIR animal imaging using UCNPs as well as other luminescent probes.
The full paper is accessible online.
18 September 2015:
A new paper has been released in Scientific Reports with two CNBP researchers as contributing authors – Dayong Jin and Xianlin Zheng. The paper detailed the successfull development of a responsive luminescence probe, TOB-Eu3+, for specific recognition and background-free quantification of vitamin C in living cells and lab animals.
Authors: Bo Song, Zhiqing Ye, Yajie Yang, Hua Ma, Xianlin Zheng, Dayong Jin & Jingli Yuan
Abstract: Sensitive optical imaging of active biomolecules in the living organism requires both a molecular probe specifically responsive to the target and a high-contrast approach to remove the background interference from autofluorescence and light scatterings. Here, a responsive probe for ascorbic acid (vitamin C) has been developed by conjugating two nitroxide radicals with a long-lived luminescent europium complex. The nitroxide radical withholds the probe on its “off” state (barely luminescent), until the presence of vitamin C will switch on the probe by forming its hydroxylamine derivative. The probe showed a linear response to vitamin C concentration with a detection limit of 9.1 nM, two orders of magnitude lower than that achieved using electrochemical methods. Time-gated luminescence microscopy (TGLM) method has further enabled real-time, specific and background-free monitoring of cellular uptake or endogenous production of vitamin C, and mapping of vitamin C in living Daphnia magna. This work suggests a rational design of lanthanide complexes for background-free small animal imaging of biologically functional molecules.
The full paper is accessible online.
27 June 2015:
Associate Investigator Dr Yiqing Lu and PhD student Mr Xianlin Zheng were CNBP attendees at CYTO 2015 – the 30th Congress of the International Society for Advancement of Cytometry held in Glasgow, June 26-30, 2015.
Oral presentations were given by both – ‘A Multifunction Workstation Underpinning Lanthanide-Based Luminescence Techniques’ by Dr Lu and ‘Precise Pinpointing of Luminescent Targets Empowers Quantitative Scanning Cytometry’ by Mr Zheng.
Dr Lu was also on the program committee.
While in the UK, both researchers took the time to visit CNBP Partner Prof Tong Sun at City University London, as well as Prof Klaus Suhling at King’s College London and Prof Peter Sadler at the University of Warwick.
28 April 2015:
Congratulations to Xianlin Zheng, a Centre PhD student, who has been selected as a recipient of the 2015 Student Travel Award for attendance at CYTO 2015 (The International Society for Advancement of Cytometry’s 30th International Congress). The event is to be held at the Scottish Exhibition and Conference Centre in Glasgow, Scotland and the grant has a value of US$1000.