THESIS
2018
xxvi, 116 pages : illustrations (some color) ; 30 cm
Abstract
Our ability to see inside living cells has largely been achieved through the use of small
fluorescent molecules. Fluorescent imaging has provided a way to non-invasively monitor the
location of organelles and biomolecules in their native environments with high spatial and
temporal resolution. In particular, fluorescent probes with emission wavelengths in the far-red to
near-infrared (FR/NIR) region are highly coveted in vivo bioimaging agents because tissue
exhibits low optical absorption and weak intrinsic autofluorescence in the FR/NIR spectral range.
Most conventional FR/NIR fluorescent probes available on the commercial market are organic
dyes which are typically encapsulated within a nanoparticle to enhance biostability, photostability
and cellular uptake. However, conventi...[
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Our ability to see inside living cells has largely been achieved through the use of small
fluorescent molecules. Fluorescent imaging has provided a way to non-invasively monitor the
location of organelles and biomolecules in their native environments with high spatial and
temporal resolution. In particular, fluorescent probes with emission wavelengths in the far-red to
near-infrared (FR/NIR) region are highly coveted in vivo bioimaging agents because tissue
exhibits low optical absorption and weak intrinsic autofluorescence in the FR/NIR spectral range.
Most conventional FR/NIR fluorescent probes available on the commercial market are organic
dyes which are typically encapsulated within a nanoparticle to enhance biostability, photostability
and cellular uptake. However, conventional organic dyes suffer from a phenomenon known as
aggregation-caused quenching (ACQ). A seminal finding by our lab revealed a new class of non-conventional
propeller-shaped fluorophores which have photophysical properties that are
diametrically opposite to the ACQ effect due to the restriction of intramolecular motion. Since our
initial report of aggregation-induced emission (AIE), many research groups have focused on
designing new FR/NIR emissive AIE compounds (AIEgens) and pure organic room-temperature
phosphorescent nanocrystals (RTP NCs) for bioimaging applications. In this thesis, we build on these established design principles to create a series of novel FR/NIR AIEgens and RTP NCs. We
examined the photophysical and non-linear optical properties of these molecules. We discovered
that the cellular uptake of FR/NIR AIEgens and RTP NCs is extremely challenging due to their
large molecular size. In order to find biological applications for these interesting molecules, we
experimented with new targeted and untargeted delivery systems including biotin-PEG and
saponin nanoparticle (NP) based delivery systems. In particular, we found the saponin delivery
systems to be biocompatible, inexpensive, ultrafast and applicable to deliver a wide variety of
FR/NIR AIEgen NPs and RTP NCs into both mammalian and plant cells.
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