UC San Diego

Phenolic materials are naturally occurring molecules present in a wide range of organisms, from fungi to bacterium, and from plants to animals. Their unique structural and chemical features can form covalent or non-covalent interactions with diverse materials including inorganic (e.g., metal ion, metal oxide, silica, gold, silver), organic (e.g., small molecule, polymers), and biomaterials (e.g., proteins, peptides). As phenolic-based material can establish multiple physicochemical interactions such as metal coordination, hydrogen bonding, interactions, hydrophobic interactions, electrostatic interactions, and covalent bonding, diverse phenolic-enabled nanostructures have been developed for biomedical applications such as phenolic nanoparticles, phenolic surface coating, and secondary growth on phenolic surface. In this dissertation, I will explain how phenolic materials can benefit nanomaterials and their role in bioimaging and biosensing applications. First chapter reviews the hybrid gold nanorod-polydopamine nanoparticles which enhance photoacoustic performance more than bare gold nanorod both in in vitro and in vivo. The role of polydopamine shell in protection for gold nanorod is largely described. Second chapter describes the impact of nanoparticle size in photoacoustic and photothermal therapy. Two different-sized gold nanorods were synthesized and coated with polydopamine. These two different sizes of polydopamine-coated gold nanorod show same extinction peak (i.e., 1064 nm); however, the small size of gold nanorod exhibits remarkable photoacoustic and photothermal performance compared to large sized particles. Third chapter studies the polydopamine nanocapsule coated with organic dyes to detect heparin in whole human blood and plasma. The dye-coated polydopamine nanocapsule showed increased photoacoustic signal as a function of heparin concentration due to particle aggregation. In this chapter, tannic acid-mediated di thiol nanoparticles were also introduced to synthesize polydopamine nanocapsules. Fourth chapter investigates the impact of skin tone on biomedical optics. Darker skin tones (i.e., phototype) absorb and scatter more incident light before it reaches to target of interest. To understand the impact of skin tone, we mimic human skin using gelatin-based hydrogel and polydopamine nanoparticles (referred as synthetic melanin) in which they have similar chemical and optical properties compared to real melanin. Using 3D-bioprinted skin phantoms, multiple biomedical optics (photoacoustic, fluorescence, and photothermal) were extensively examined. Fifth chapter includes peptide-driven particle dissociation of gold nanoparticle aggregates for protease detection. Gold nanoparticle aggregation is often hindered by protein corona formation in biofluid, and undesired aggregation can produce false positives. In this chapter, diverse peptide structures were investigated for a matrix-insensitive dissociation platform.