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Proceedings Paper • Open Access

Multiphoton microscopy and image guided light activated therapy using nanomaterials (Conference Presentation)
Author(s): Paras N. Prasad

Paper Abstract

This talk will focus on design and applications of nanomaterials exhibiting strong multiphoton upconversion for multiphoton microscopy as well as for image-guided and light activated therapy .1-3 Such processes can occur by truly nonlinear optical interactions proceeding through virtual intermediate states or by stepwise coupled linear excitations through real intermediate states. Multiphoton processes in biocompatible multifunctional nanoparticles allow for 3D deep tissue imaging. In addition, they can produce in-situ photon conversion of deep tissue penetrating near IR light into a needed shorter wavelength light for photo-activated therapy at a targeted site, thus overcoming the limited penetration of UV or visible light into biological media. We are using near IR emitters such as silicon quantum dots which also exhibit strong multiphoton excitation for multiphoton microscopy. Another approach involves nonlinear nanocrystals such as ZnO which can produce four wave mixing, sum frequency generation as well as second harmonic generation to convert a deep tissue penetrating Near IR light at the targeted biological site to a desired shorter wavelength light suitable for bio imaging or activation of a therapy. We have utilized this approach to activate a photosensitizer for photodynamic therapy. Yet another type of upconversion materials is rare-earth ion doped optical nanotransformers which transform a Near IR (NIR) light from an external source by sequential single photon absorption, in situ and on demand, to a needed wavelength. Applications of these nanotransformers in multiphoton photoacoustic imaging will also be presented. An exciting direction pursued by us using these multiphoton nanoparticles, is functional imaging of brain. Simultaneously, they can effect optogenetics for regioselective stimulation of neurons for providing an effective intervention/augmentation strategy to enhance the cognitive state and lead to a foundation for futuristic vision of super human capabilities. Challenges and opportunities will be discussed.

Paper Details

Date Published: 24 April 2017
PDF: 1 pages
Proc. SPIE 10069, Multiphoton Microscopy in the Biomedical Sciences XVII, 1006902 (24 April 2017); doi: 10.1117/12.2256596
Show Author Affiliations
Paras N. Prasad, Univ. at Buffalo (United States)

Published in SPIE Proceedings Vol. 10069:
Multiphoton Microscopy in the Biomedical Sciences XVII
Ammasi Periasamy; Peter T. C. So; Karsten König; Xiaoliang S. Xie, Editor(s)

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