MSc Thesis Presentation: Synthesis of Gold Nanoparticles via Laser Ablation in the Presence of Phytoglycogen

MSc Candidate

Joshua Sampson

Abstract

Phytoglycogen is a naturally occurring glucose-based polymer that has promising applications in personal care, nutrition, and biomedicine. Gold nanoparticles were generated using two-step laser ablation in pure Milli-Q water (AuNP) and Milli-Q containing phytoglycogen (AuNP-Phg) and the size, shape, and nanoparticle concentration were characterized using TEM, DLS, UV-Vis and ICP-OES. AuNP showed a unimodal distribution of diameters, peaked at 8.8 nm, whereas AuNP-Phg showed a bimodal distribution: smaller particles, peaked at 4.1 nm, had their growth limited by phytoglycogen; and larger particles, peaked at 7.9 nm, grew unhindered. AuNP, AuNP-Phg and AuNP subsequently mixed with phytoglycogen (AuNP+Phg) were used to catalyze the reduction of 4-nitrophenol, measured using UV-Vis and analyzed using the Langmuir-Hinshelwood model. The dispersions had similar best-fit values of the Langmuir-Hinshelwood parameters ; however, the average surface-normalized apparent rate constant (k_s^ave) was smaller and the induction period was larger for AuNP+Phg compared to AuNP and AuNP-Phg. This suggests that phytoglycogen associates with the gold nanoparticles, preventing the reagent from reaching the catalytic sites.

Examination Committee

• Dr. Hermann Eberl, Chair
• Dr. John Dutcher, Advisor
• Dr. Stefan Kycia
• Dr. Aicheng Chen