Synthesis and cell uptake study of plasmonic gold nanoparticles and nanostars with magnetic cores

Hyon Min Song, Purdue University

Abstract

Chemical aspect of gold nanoparticles and nanostars with magnetic cores is described, focusing on the wet chemical synthesis and cell uptake study. Gold nanomaterials have unique plasmon resonance peaks depending on their shape and size. Hybridization with magnetic materials provides additional contrast to their intrinsic scattering. However, dielectric properties of metal oxides significantly reduce scattering intensity of the hybridized materials. A seed-mediated approach has been devised by growing branched gold nanostars with the intact sharp arms being outside of the magnetic cores. The resulting nanostars have desirable plasmon peaks in the near-infrared region, which is the best window for the penetration of light into biological media, and they also possess magnetic properties strong enough to be modulated to the external magnetic field. In their growth behaviors, irregular and randomly distributed twin boundaries are observed in Fe3O4@Au core-shell nanoparticles. Unusual {110} planes, and misfit {111} planes are observed on their shell structures, which is believed to compensate for the large surface energy of core-shell structures. As in the core-shell nanoparticles, twin boundaries are universal phenomena in gold nanostars, with twin boundary bisecting tip region, or with multiple parallel twin boundaries residing along the growth direction. Single crystalline tips are also observed without twin boundaries, but stacking faults accompany in the boundaries between different lattice planes. With these spherical core-shell nanoparticles and branched nanostars, cytotoxicity and immuine response of macrophages (RAW 264.7) are studied. Cytotoxicity measured by MTT assay indicates that macrophages incubated with core-shell nanoparticles have lower viability than those incubated with nanostars. Measurements of ROS level, TNF-α release, cell size and cell complexity by scattering methods, and observation of the cell morphology suggest that macrophages incubated with BSA-coated nanostars follow similar pro-inflammatory pathway as those incubated with LPS. Rotating magnetic field gradient increases ROS production in macrophages incubated with nanostars, due to the inflammatory response induced by the spiky tips on nanostars. In macrophages incubated with BSA-coated nanoparticles, ROS production, TNF-α measurement, cell viability, and scattering data indicate that the behavior is close to normal cells without affecting inflammatory response.

Degree

Ph.D.

Advisors

Wei, Purdue University.

Subject Area

Inorganic chemistry|Nanotechnology|Materials science

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