Nanoparticles (NPs) are emerging as attractive drug carriers in therapeutic and diagnostic applications. The physiochemical properties of NPs, such as particle size, shape, and surface chemistry, play important roles in the functions of engineered nanoconstructs−NP cores with surface ligands. Recent work has screened these properties by monitoring cellular uptake and/or sub-cellular distribution; however, most works have been limited to static analysis at specific time points. The real-time information during NP-cell interactions is lost, and local mechanisms remain unknown. Single-particle tracking is a powerful approach to study dynamic processes in NP-cell interactions and provides access to nanoconstruct behavior in cellular environments, which requires both appropriate optical probes and optical microscopy techniques.This dissertation discusses the application of anisotropic gold stars (AuNS) in investigating the NP-cell interactions in real time via differential interference contrast (DIC) microscopy. DIC microscopy is favorable for single-particle tracking because it is insensitive to the scattering of cellular compartments and enables imaging at different cell planes. AuNS are advantageous optical probes because they are synthesized with biocompatible buffers and can be covalently functionalized with various drugs or ligands; the strong scattering properties of AuNS necessitate no additional labels in DIC microscopy. Anisotropic AuNS exhibit orientation-dependent DIC image patterns, which facilitates simultaneous tracking of translational and rotational motions. Accurate determination of AuNS orientation based on the DIC images rely on the high shape homogeneity in the particle solutions. Rotational dynamics of AuNS, however, can still be investigated based on the DIC contrast analysis although the accurate orientation angle prediction has not been achieved. Through comparing the single-particle dynamics of targeting and non-targeting nanoconstructs, we confirm the binding specificity of surface ligands towards transmembrane proteins are maintained even in the existence of non-specifically adsorbed proteins. In addition, I prove that the core shape determines the specificity of targeting nanoconstructs on cell membranes in an in vitro environment. With fluorescently labeled cell compartments, our imaging system, AuNS probes and DIC-epifluorescence microscopy, can be expanded to examine NP-cell interactions within different organelles, which provide insights into the connectivity between distinct stages of multi-step biological processes.

Creator

• Liu, Tingting

DOI

• https://doi.org/10.21985/n2-5yeg-p587

Subject

• Chemistry

Language

• en

Alternate Identifier

• etdadmin_upload_844987
• http://dissertations.umi.com/northwestern:15753

Date created

• 2021-01-01

Resource type

• Dissertation

Rights statement

• In Copyright