Nanophotonics for Biotechnology and Nanomedicine

Abstract

Nanophotonics broadly impacts biomedical research and technology for studying the fundamentals of interactions and dynamics at single cell/molecule level, as well as for applications to light-guided and light-activated therapy using nanomedicine. Nanomedicine is an emerging field that deals with utilization of nanoparticles in the development of new methods of minimally invasive diagnostics for early detection of diseases, as well as for facilitating targeted drug delivery, effectiveness of therapy, and real-time monitoring of drug action. This chapter illustrates a broad range of potential applications by providing some demonstrative examples. A fundamental understanding of drug-cell interactions, based on molecular changes at the single-cell level induced by a pre-onset state of a disease, can provide a basis for molecular recognition-based "personalized" therapeutic approaches to treat diseases. Nanophotonics enables one to use optical techniques for tracking of drug intake, elucidating its cellular pathway and monitoring subsequent intracellular interactions. For this purpose, bioimaging, biosensing, and single-cell biofunction studies, using optical probes, are proving to be extremely valuable.In the area of nanomedicine-based molecular recognition of diseases, light-guided and light-activated therapies provide a major advancement. Nanoparticles containing optical probes, light-activated therapeutic agents, and specific carrier groups that can direct the nanoparticles to the diseased cells or tissues provide targeted drug delivery, with an opportunity for real-time monitoring of drug efficacy. This chapter provides some examples of both optical diagnostics and light-based therapy.Section 13.1 illustrates the usage of near-field microscopy, a technique already discussed in Chapter 3, for bioimaging of microbes and biostructures that are of dimensions considerably less than the wavelengths of light used. Section 13.2 provides a general description of nanophotonic approaches for optical diagnostics and light-activated and guided therapy. Section 13.3 presents semiconductor quantum dots for bioimaging. These quantum dots and their size-dependent optical properties have been discussed in Chapter 4. Section 13.4 covers up-converting nanoparticles for bioimaging. These nanoparticles, containing rare-earth ions, absorb in the IR and emit in the visible spectral range and have been discussed in Chapter 6. Merits of these inorganic emitters over the organic fluorophores are also described in their respective sections.