Publication Date

2017-04-25

Availability

Open access

Embargo Period

2017-04-25

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Chemistry (Arts and Sciences)

Date of Defense

2017-04-04

First Committee Member

Françisco M. Raymo

Second Committee Member

Roger M. LeBlanc

Third Committee Member

James N. Wilson

Fourth Committee Member

James D. Baker

Abstract

Self-assembling nanoparticles of amphiphilic polymers can transport hydrophobic molecules across hydrophilic media and, as a result, can be valuable delivery vehicles for a diversity of biomedical applications. We designed molecular guests with photoactivatable fluorescence for these supramolecular hosts and demonstrated that the activation of the fluorescent cargo, under optical control, permits the tracking of the nanocarrier translocation across hard and soft matrices with the sequential acquisition of fluorescence images. In addition, the supramolecular delivery of these photoactivatable probes into the cellular blastoderm of Drosophila melanogaster embryos allows the real-time visualization of translocating molecules with no detrimental effects on the developing organisms. These photoresponsive compounds combine a borondipyrromethene (BODIPY) chromophore and a photocleavable oxazine within their covalent skeleton. The designed photoactivation mechanism permits the conversion of an emissive reactant into an emissive product with resolved fluorescence, under mild illumination conditions that are impossible to replicate with conventional switching schemes based on bleaching. In fact, these operating principles allow the photoactivation of BODIPY fluorescence with large brightness and infinite contrast. Thus, our innovative structural design translates into activatable fluorophores with excellent photochemical and photophysical properties as well as provides access to a general mechanism for the real-time tracking of supramolecular nanocarriers in hydrophilic matrices. The fluorescence of a carbazole chromophore and a halochromic indolizine heterocycle can be activated irreversibly under optical control. The former incorporated a photochromic oxazine ring and the latter operated with a co-entrapment photoacid generator doped in polymer films. Both of them allow the imprinting of fluorescent patterns in the resulting materials. These operating principles enable the writing and reading of microscaled information under optical control at low illumination intensities.

Keywords

Photoactivatable fluorophore; Supramolecular nanocarriers; Drosophila Melanogaster; Boron Dipyrrolemethene; Fluorescent patterning

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