Real-time optical distance sensing of up-conversion nanoparticles with a precision of 2.8 nanometers

Team of researchers demonstrated ultra-precise localization and tracking of fluorescent nanoparticles

Calculated self-interference of a single nanoparticle placed on a mirror substrate with a silica layer as the spacer. (i), (ii) and (iii) show different cuts through the far-field patterns of oriented dipoles oscillating along the x,y and z-axis, respectively. Credit: O. Benson, IRIS Adlershof

Sub-diffraction limited localization of fluorescent emitters is a major goal of microscopy imaging. It is of key importance for so-called super-resolution, a technique that was awarded the Nobel Prize in Chemistry in 2014. A cooperation of researchers in Australia, China, the USA and IRIS Adlershof have now demonstrated ultra-precise localization and tracking of fluorescent nanoparticles dispersed on a mirror. The many randomly oriented molecular dipoles in such up-conversion nanoparticles (UCNPs) interfere with their own mirror images and create unique, bright and position-sensitive patterns in the spatial domain.

The pattern can be detected in the far-field by a sensitive camera and was compared to a detailed and quantitative numerical simulation. In this way it was possible to localize individual particles with an accuracy of only 2.8 nm, a value which is smaller than 1/350 of the excitation wavelength.

The localization can be performed rapidly, and a single particle can be followed with a 50Hz frame rate. This is much faster than other self-interference-based methods based on mapping of the fluorescence spectrum. A special benefit of UCNPs is their high photo-stability and sensitivity, e.g. to temperature and PH. Therefore, the novel technique may be used for high-resolution multimodality single-particle tracking and sensing.

Publication

Axial Localization and Tracking of Self-interference Nanoparticles by Lateral Point Spread Functions
Y. Liu, Z. Zhou, F. Wang, G. Kewes, S. Wen, S. Burger, M. Ebrahimi Wakiani, P. Xi, J. Yang, X. Yang, O. Benson, and D. Jin
Nat. Commun. 12 (2021) 2019, DOI: 10.1038/s41467-021-22283-0

Further information

IRIS Adlershof
Prof. Dr. Oliver Benson
Humboldt-Universität zu Berlin
Department of Physics
Phone: +49 30 2093-4711
Email: oliver.benson(at)physik.hu-berlin.de
www.iris-adlershof.de

Source: IRIS Adlershof, 13 April 2021