UTFacultiesTNWMMEventsPhD defense Min Lin

PhD defense Min Lin Silicon-based micro- and nanoparticles: preparation, functionalization and hyperpolarized magnetic resonance imaging.

Silicon is an important component of many materials in daily life, ranging from cement to polymers, alloys to electronics, drug delivery to disease diagnosis. Silicon-based nanoparticles display quantum confinement effects and have high surface-to-volume ratios as compared to bulk silicon. Owing to these characteristics, they often have unique physicochemical properties, such as thermal or electrical conductivity, magnetic properties, and even antimicrobial activity. Silicon-based particles can either be made by breaking down bulk materials (top-down) or by controlled assembly (bottom up). Their properties usually strongly depend on size, synthetic approaches and surface chemistry. Silicon-based particles have been widely utilized in biomedical applications, such as drug delivery and bioimaging. In this thesis, we explore promising silicon-based particles with favorable size and good colloidal stability for application in biomedical imaging, particularly magnetic resonance imaging (MRI).

We focus on two silicon-based ceramic materials: non-porous silicon particles (> 10 nm) and silicon carbide (SiC) due to their potential for MRI via hyperpolarization. The research described in this thesis aims at promoting the feasibility and versatility of silicon-based particles for hyperpolarized MRI. Specifically, for SiNPs with demonstrated hyperpolarization potential, we improve their stability by surface modification such as polymer grafting or lipid coating (Chapter 3 and Chapter 4), as well as explore available methods for the preparation of non-agglomerated silicon particles (Chapter 5). For silicon carbide, both 13C and 29Si are MR visible and within the tuning ranges of commercial multinuclear MRI systems. SiC therefore presents an interesting yet hardly explored material for hyperpolarization via DNP. Factors that may affect DNP enhancements and T1 relaxation times such as crystal structure, size, and chemical composition are under consideration (Chapter 6).