Naphthalimides Exhibiting Aggregation-Induced Emission for Bioimaging Applications
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Louisa Constance Sigurvinsson, 'Naphthalimides Exhibiting Aggregation-Induced Emission for Bioimaging Applications'Download Item:
Abstract:
In this project, a 1,8-naphthalimide (Nap, compound 8) is functionalised with two triphenylamino (TPA) moieties which, by virtue of having multiple freely rotating aromatic rings, are capable of exhibiting aggregation-induced emission (AIE) in aqueous environments. The synthesis of this Nap is undertaken via a double Suzuki-Miyaura coupling procedure and the compound is fully characterised using 1H and 13C NMR, IR, mass spectrometry, elemental analysis. Its structure has been determined unequivocally by single crystal X-ray diffraction. Photophysical studies reveal that the emission of 8 is blueshifted and more emissive in apolar solvent media, originating from a planarized, charge transfer (CT) state. By contrast, the emission redshifts and becomes quenched in polar media as it adopts a twisted, intramolecular charge transfer state (TICT). Accordingly, in pure THF, 8 is emissive but upon addition of a small amount of water, the fluorescence is immediately quenched. However, at a critical water content (>70% water in THF), 8 once again becomes luminescent; although the bulk solvent environment is more polar, the local environment experienced by the AIEphore within the aggregates is less polar and thus the emission switches on again. The self-assembly into emissive aggregates was studied further using scanning electron microscopy (SEM) and, with a view to using 8 as an imaging agent, its self-assembly into a nanoparticle loaded with 8 (poloxamer P188) was demonstrated using dynamic light scattering (DLS). These successfully synthesised Nap loaded nanoparticles were then tested as bioimaging agents and 8 was found to undergo localisation within the lipid droplets of MDA-MB-231 human breast cancer cells following release from the poloxamer within the cell.
Author: Sigurvinsson, Louisa Constance
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Gunnlaugsson, ThorfinnurQualification name:
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