gold nanoparticle uptake in situ TEM
Image courtesy of Microsc Microanal

Abstract

The size of gold nanoparticles (AuNPs) can influence various aspects of their cellular uptake. Light microscopy is not capable of resolving most AuNPs, while electron microscopy (EM) is not practically capable of acquiring the necessary statistical data from many cells and the results may suffer from various artifacts. Here, we demonstrate the use of a fast EM method for obtaining high-resolution data from a much larger population of cells than is usually feasible with conventional EM. A549 (human lung carcinoma) cells were subjected to uptake protocols with 10, 15, or 30 nm diameter AuNPs with adsorbed serum proteins. After 20 min, 24 h, or 45 h, the cells were fixed and imaged in whole in a thin layer of liquid water with environmental scanning electron microscopy equipped with a scanning transmission electron microscopy detector. The fast preparation and imaging of 145 whole cells in liquid allowed collection of nanoscale data within an exceptionally small amount of time of ~80 h. Analysis of 1,041 AuNP-filled vesicles showed that the long-term AuNP storing lysosomes increased their average size by 80 nm when AuNPs with 30 nm diameter were uptaken, compared to lysosomes of cells incubated with AuNPs of 10 and 15 nm diameter.

Impact Statement

The use of a rapid electron microscopy method (EM) to retrieve high-resolution data from a greater population of cells than a conventional EM is typically capable of measuring. The researchers subjected A549 cells to uptake protocols with 10, 15 and 30 diameter AuNP and adsorbed proteins. After 20 minute, 24 hour and 45 hour intervals, the whole cells were fixed and imaged in liquid water using environmental scanning electron microscopy with a scanning transmission electron microscopy detector.