Publication Date

2012-02-02

Availability

Open access

Embargo Period

2012-02-02

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Chemistry (Arts and Sciences)

Date of Defense

2012-01-31

First Committee Member

Francisco M. Raymo

Second Committee Member

Angel E. Kaifer

Third Committee Member

Roger M. Leblanc

Fourth Committee Member

Balakrishna L. Lokeshwar

Abstract

Fluorescence microscopy offers the opportunity to image biological samples noninvasively in real time and has become an essential analytical tool in the biomedical laboratory. Nonetheless, the phenomenon of diffraction imposes stringent limitations on the resolving power of conventional microscopes, preventing the spatial resolution of fluorescent species co-localized within areas of nanoscaled dimensions. Time, however, can be exploited to distinguish fluorophores within the same subdiffraction area, if their fluorescence can be switched independently, and reconstruct sequentially their spatial distribution. In this context, photolytic reactions and photochromic transformations can be invoked to switch fluorescence under optical control. Fluorescent units, such as inorganic semiconductor nanoparticles and organic dyes, and photoactive components can be operated within a common supramolecular matrix or integrated within the same molecular construct to produce photoswitchable fluorescent assemblies. In the resulting systems, electronic communication between the components can be designed in order to photoactivate or photodeactivate fluorescence respectively. Both mechanisms can be exploited to overcome diffraction, and ultimately permit the reconstruction of images with resolution down to the nanometer level, in combination with appropriate illumination protocols.

Keywords

Fluorescence; photoswitchable probes; super-resolution microscopy; bio-imaging; photochromic compounds; luminescence switching

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