Microscopic 5-D tracking of single nanoparticles in living cells by “naked eye”.
Institute for Biomedical Materials and Devices (IBMD), Faculty of Science, University of Technology Sydney, NSW 2007, Australia
Human’s eye has better photo-sensitivity than cameras for low light vision. Here we determine that under a microscope ~ 4154 photons per 100 milliseconds are needed for our eyes to directly tell the colour, intensity and location of a single nanoparticle. We demonstrate a library of mono-disperse and emission-tunable upconversion nanoparticles, each emits highly bright, uniform and photo-stable signals for long-term quantitative analysis of single nanoparticles in living cells. With high temporal, spectral and spatial resolutions, we show that the technique for real-time discrimination of single nanoparticles further allows nanoscale measurement of the viscosity of intracellular organelles over a large dynamic range of 11.57 cP to 40952.87 cP. Moreover, beyond colour recognition of each single nanoparticles, we introduce the excitation power density as the fifth dimension for our eyes to simultaneously tell multiple kinds of single nanoparticles, in which scheme nanoparticles doped by different concentration of emitters take turn to shine according to different excitation densities.
Dr. Wang obtained his Ph.D. from UNSW in 2013 for his studies exploring optical properties of single nanoparticles utilizing optical tweezers. From 2013 to 2015, Dr. Wang worked as a Postdoctoral Research Fellow in Prof. Jagadish’s group at the ANU studying carrier dynamics and nanophotonic properties of semiconductor nanowires. Since 2015, Dr. Wang has been part of the ARC center of excellence for nanoscale biophotonics (CNBP) at Macquarie University node, developing novel bioimaging method. From 2017, Dr. Wang joined Prof. Jin’s group in UTS to lead the photonic research, developing bioimaging application of up-conversion nanoparticles.