Nanotechnology for Biophotonics Bionanophotonics

Some describe us as living in an era of Nanomania where there is a general euphoria about nanoscale science and technology. The fusion of nanoscience and nanotechnology with biomedical research has also broadly impacted biotechnology. The subject covered in this chapter, however, is more focused, dealing with the interface between biomedical science and technology and nanophotonics, hence the term bionanophotonics. Nanophotonics is an emerging field that describes nanoscale optical science and technology.

Specifically, this chapter discusses the use of nanoparticles for optical bioimaging, optical diagnostics, and light-guided and activated therapy. Section 15.2 describes the power of nanochemistry to produce the various nanoparti-cles and tailor their structures and functions for biomedical applications. Specific examples provided for bioimaging are two classes of nanoparticle emitters. One consists of semiconductor nanoparticles, also known as quantum dots, whose luminescence wavelength is dependent on the size and the nature of the semiconductors. These nanoparticle emitters can be judiciously selected to cover the visible to the IR spectral range. They can also be surface-functionalized to be dispersable in biological media as well as to be conjugated to various biomolecules.

Another class of nanoparticle emitters for bioimaging consists of up-converting nanophores comprised of rare-earth ions in a crystalline host. They convert near-IR and IR radiation, which can penetrate deeper into a tissue, to emissions in the visible range by utilizing the process of sequential multiphoton absorption. In addition to bioimaging, the up-converting nanophores can also allow treatment of deeper tumors by using them for multiphoton photo-dynamic therapy described in Chapter 12. The use of metallic nanoparticles and nanorods for biosensing is described in Section 15.5.

The next two sections, 15.6 and 15.7, describe the use of a nanoparticles platform, for intracellular diagnostic and targeted drug delivery. Section 15.6 discusses the PEBBLE nanosensors approach for monitoring intercellular

Introduction to Biophotonics, by Paras N. Prasad.

ISBN: 0-471-28770-9 Copyright © 2003 John Wiley & Sons, Inc.


activities. Section 15.7 discusses the use of nanoclinics, which are thin silica shells (packaging various probes for diagnostics and agents for external activation) and are surface-functionalized with carrier groups to target specific biological sites such as cancer cells.

The chapter concludes with a discussion of future directions of research and development in bionanophotonics. For further reading, the following reviews are recommended:

Shen et al. (2000): A feature review article on nanophotonics

Murray et al. (2002): A review on synthesis and characterization of nanocrystals

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