A Simple Spectroscopic Method for Differentiating Cellular Uptakes of Gold Nanospheres and Nanorods from Their Mixtures

摘要

Owing to their unique optical (scattering and absorption) properties, gold-based nanostructures have recently been applied to many applications related to biomedical research. For example, Au nanostructures have been demonstrated as either contrast agents for optical imaging (and therefore cancer diagnosis) or therapeutic agents for photothermal ablation of cancer by making use of the scattering and absorption components. Furthermore, Au nanostructures have been exploited as probes or carriers to evaluate the delivery efficacy of nanomedicine into target cells or tissues. This variety of applications is found because Au nanostructures of various sizes and shapes can now be synthesized in relatively large quantities; their surfaces can be readily derivatized with different functional groups through the well-established gold thiolate chemistry; and the content of Au in a specific number of cells or amount of tissue can be accurately determined with high sensitivity using inductively coupled plasma mass spectrometry (ICP-MS). However, ICP-MS simply cannot differentiate different types of Au nanostructures in a mixture. As a result, it is necessary to conduct a large number of in vitro or in vivo experiments separately to compare Au nanostructures with different sizes, shapes, or surface chemistries. Since cell culture and animal studies are highly sensitive to experimental conditions, doing experiments separately (even side-by-side) is expected to introduce errors. Moreover, different types of Au nanostructures must be mixed together for any possible interference between the uptakes of different nanostructures to be observed. In these regards, it will be a great advantage to supply different types of Au nanostructures as a mixture and then follow their cellular uptakes simultaneously in the same experiment.