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Jin D.,Macquarie University | Piper J.,Macquarie University | Yuan J.,Dalian University of Technology | Leif R.,Newport Instruments
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2010

In advanced cytometry, a fundamental challenge for rapid specific detection of rare-event micro-organisms is the autofluorescence noise from the complex biological samples. Time-gated luminescence can effectively discriminate labeled cells from autofluorescence background. Recently, a real-time true-colour time-gated luminescence microscopy system has been developed based on the synchronization of a solid-state excitation source and a super-fast optical shutter. We also developed a variety of ultra-bright silica nano-biolabels with multiple luminescence colours and controllable lifetimes in microsecond range. These developments allowed the development of an advanced cell analysis system for real-time background-free imaging and rare-event counting of microsecond-lifetime multi-colour labelled water-borne pathogens. © 2010 Copyright SPIE - The International Society for Optical Engineering. Source

Lu Y.,Macquarie University | Lu Y.,Tsinghua University | Jin D.,Macquarie University | Leif R.C.,Newport Instruments | And 5 more authors.
Cytometry Part A | Year: 2011

Many microorganisms have a very low threshold (<10 cells) to trigger infectious diseases, and, in these cases, it is important to determine the absolute cell count in a low-cost and speedy fashion. Fluorescent microscopy is a routine method; however, one fundamental problem has been associated with the existence in the sample of large numbers of nontarget particles, which are naturally autofluorescent, thereby obscuring the visibility of target organisms. This severely affects both direct visual inspection and the automated microscopy based on computer pattern recognition. We report a novel strategy of time-gated luminescent scanning for accurate counting of rare-event cells, which exploits the large difference in luminescence lifetimes between the lanthanide biolabels, >100 μs, and the autofluorescence backgrounds, <0.1 μs, to render background autofluorescence invisible to the detector. Rather than having to resort to sophisticated imaging analysis, the background-free feature allows a single-element photomultiplier to locate rare-event cells, so that requirements for data storage and analysis are minimized to the level of image confirmation only at the final step. We have evaluated this concept in a prototype instrument using a 2D scanning stage and applied it to rare-event Giardia detection labeled by a europium complex. For a slide area of 225 mm2, the time-gated scanning method easily reduced the original 40,000 adjacent elements (0.075 mm × 0.075 mm) down to a few "elements of interest" containing the Giardia cysts. We achieved an averaged signal-to-background ratio of 41.2 (minimum ratio of 12.1). Such high contrasts ensured the accurate mapping of all the potential Giardia cysts free of false positives or negatives. This was confirmed by the automatic retrieving and time-gated luminescence bioimaging of these Giardia cysts. Such automated microscopy based on time-gated scanning can provide novel solutions for quantitative diagnostics in advanced biological, environmental, and medical sciences. © 2011 International Society for Advancement of Cytometry. Source


Agency: Department of Health and Human Services | Branch: | Program: STTR | Phase: Phase II | Award Amount: 249.96K | Year: 1999


Newport Instruments | Date: 2002-03-28

Laboratory Equipment, namely sample processor used for processing biological fluid samples used to manufacture cytologic or particle preparations.

Lu Y.,Macquarie University | Lu J.,Macquarie University | Zhao J.,Macquarie University | Cusido J.,University of Miami | And 10 more authors.
Nature Communications | Year: 2014

Significant multiplexing capacity of optical time-domain coding has been recently demonstrated by tuning luminescence lifetimes of the upconversion nanoparticles called 'τ-Dots'. It provides a large dynamic range of lifetimes from microseconds to milliseconds, which allows creating large libraries of nanotags/microcarriers. However, a robust approach is required to rapidly and accurately measure the luminescence lifetimes from the relatively slow-decaying signals. Here we show a fast algorithm suitable for the microsecond region with precision closely approaching the theoretical limit and compatible with the rapid scanning cytometry technique.We exploit this approach to further extend optical time-domain multiplexing to the downconversion luminescence, using luminescence microspheres wherein lifetimes are tuned through luminescence resonance energy transfer.We demonstrate real-time discrimination of these microspheres in the rapid scanning cytometry, and apply them to the multiplexed probing of pathogen DNA strands. Our results indicate that tunable luminescence lifetimes have considerable potential in high-throughput analytical sciences. © 2014 Macmillan Publishers Limited. All rights reserved. Source

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