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Particle tracking in three-dimensions using multiphoton luminescence in gold nanoparticles

English title Particle tracking in three-dimensions using multiphoton luminescence in gold nanoparticles
Applicant Ricka Jaroslav
Number 113284
Funding scheme Project funding (Div. I-III)
Research institution Institut für angewandte Physik Universität Bern
Institution of higher education University of Berne - BE
Main discipline Other disciplines of Physics
Start/End 01.10.2006 - 30.11.2009
Approved amount 293'199.00
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Keywords (7)

femtosecond laser; ultra-short pulse laser; multiphoton microscopy; multiphoton luminescence; three-dimensional particle tracking; particle tracking; gold nanoparticle

Lay Summary (English)

Lay summary
Advances in optical microscopy and image analysis have made it possible to track single biological molecules and structures, even within the cytoplasm of living cells. Many biological studies have relied on fluorescent labeling of the proteins, DNA or RNA molecules, and other biological structures under investigation. While fluorescent labels-single molecules or fluorescent beads-have found myriad applications, they have several key disadvantages: they photobleach rapidly and they can be toxic to living cells. Single fluorophores blink on and off and their detection is often difficult or impossible given the background auto-fluorescence of cells. Gold nanoparticles, which do not photobleach, do not blink, and are non-toxic, present a new label that can be used in particle tracking applications. It has recently been demonstrated that gold nanoparticles emit significant luminescence when excited through multiphoton processes using tightly focused near-infrared light from an ultra-short pulse laser.
Multiphoton processes can only occur at sufficiently high electric field strengths, limiting them to a small focal region and thus providing high spatial resolution in both the lateral and axial directions at depths up to several hundred micrometers inside a biological sample. We will investigate multiphoton luminescence in gold nanoparticles and apply this technique to the three-dimensional tracking of biological structures.
Gold nanospheres are commercially available in a range of sizes and gold nanorods can be generated using simple recipes available in the literature. The first part of the project will involve careful characterization of the multiphoton absorption cross-section of gold nanoparticles of different shapes and sizes, allowing us to determine the optimum particle for different applications. We will take advantage of and extend a new technique recently developed in our group to measure the two-photon absorption cross-section of fluorescent dyes. The second part will focus on the development and incorporation into an existing multiphoton microscope of an active particle tracking system. Particle tracking is an important technique in biology, but the fluorophores typically used as labels limit the time duration over which a particle can be tracked. In addition, conventional particle tracking techniques are often limited to two dimensions. Using multiphoton luminescence of gold nanoparticles, we hope to overcome these limitations and develop a technique with a wide range of applications in biology, including in areas, such as the study of the beating of cilia, under investigation in our laboratories.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
127274 Deep optoacoustic imaging with nanoparticle enhanced contrast 01.10.2009 Project funding (Div. I-III)
126957 Biomedical applications of femtosecond lasers: Gold colloids and phospholipid membranes. 01.10.2009 Project funding (Div. I-III)