Size‐Controlled Synthesis of Highly Monodisperse Gold Nanoparticles without a Size‐Selection and Long Range Ordered 2‐D Arrangement

Effect of Gold Nanoparticles on Fluorescence Properties of Hyperbranched Poly(amido amine)s

Hyperbranched poly (amino amine) s (HPAMAMs), synthesized by Michael addition of 1-(2-aminoethyl) piperazine (AEPZ) and methyl acrylate (MA), can emit blue fluorescence under excitation wavelength. However, the relatively weak fluorescence of HPAMAMs is still an obstacle for its practical applications. Gold is one of the most frequently used metals for fluorescence enhancement. In this research, the influence of gold nanoparticles on fluorescence property of HPAMAMs was investigated by fluorometry. It was found that gold nanoparticles (GNPs) with smaller size (< 5 nm) presented greatly enhanced emission. The GNPs with larger size (~10 nm in diameter) and definite surface plasmon absorption can quench the fluorescence of HPAMAMs.

Quantitatively modeling the equilibrium properties of thiol-decorated gold nanoparticles

We employ a molecular mean-field theory to quantitatively understand the sizes, surfactant surface coverage, and size fluctuations of gold nanocrystals decorated with thiol surfactants of different chain lengths. Our model assumes that surfactant-coated nanoparticles are equilibrium structures. We find that packing constraints experienced by the surfactant tails are less significant for more curved (smaller) particles. This effect enables us to rationalize the experimental observations/deductions that the thiol coverage per unit area increases with decreasing particle size. The reduction of surface coverage with increasing size also explains the fact that size polydispersity increases with increasing nanoparticle size. We find that increasing the length of the surfactants results in larger nanoparticles.