Self-assembly of individual p-conjugated dye molecules to supramolecular J- and H-aggregates has gained significant interest in recent years owing to superior optoelectronic properties that are different from the individual dye molecules. J-aggregates are formed when dye molecules are stacked in a head-to-tail fashion giving rise to a red-shifted absorption band compared to the monomer absorption band. In comparison, H-aggregates arise due to face-to-face stacking of dye molecules, thereby giving rise to a blue-shifted absorption band. The strong interaction of dye molecules in J- and H-aggregates results in delocalized excitations useful as an efficient photo-induced electron transfer (PET) probe for sensing biomolecules. However, morphology, size, and stability remain a challenge for biomolecule detection. Dopamine (DA) is an important neurotransmitter essential for transmitting signals in neuronal communications. The deficiency of DA has implications for neurological disorders. In this thesis, we report a controlled synthesis of J- and H-aggregates and use them as an efficient PET probe for the sensitive detection of DA. First, we demonstrate the self-assembly of 3,3'-diethythiadicarbocyanine iodide (DiSC2(5)) in ammonia solution to form H-aggregate nanoparticles. We then use these nanoparticles to detect DA in a synthetic urine medium. Second, we demonstrate lithocholic acid (LCA) and DiSC2(5) coassembly at the equimolar ratio in ammonia solution into J-aggregate nanotubes. By integrating the J-aggregate nanotubes into transparent agarose hydrogel film, we fabricate a portable and reproducible sensor platform for the optical detection of DA in synthetic urine. Third, we report the formation of fluorescent H-aggregates in an inclined arrangement with vesicular and tubular morphologies by the self-assembly of 3,3'-diethylthiacarbocyanine iodide (DiSC2(3)) in ammonia/methanol mixtures. Finally, we use the above H-aggregates to detect DA released by M17 human neuroblastoma cells by stimulating the cells with nicotine. The sensitive and straightforward PET probe of H-aggregate nanoparticles has the potential for early diagnosis of neurological disorders.


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Graduation Date





Fang, Jiyu


Doctor of Philosophy (Ph.D.)


College of Engineering and Computer Science


Materials Science and Engineering

Degree Program

Materials Science and Engineering




CFE0009047; DP0026380





Release Date

May 2025

Length of Campus-only Access

3 years

Access Status

Doctoral Dissertation (Campus-only Access)

Restricted to the UCF community until May 2025; it will then be open access.