Uptake of Functional Ultrasmall Gold Nanoparticles in 3D Gut Cell Models

Ultrasmall gold nanoparticles (2 nm) easily penetrate the membranes of intestinal murine epithelial cells (MODE-K) and colorectal cancer cells (CT-26). They are also taken up by 3D spheroids (400 mu m) of these cell types and primary gut organoids (500 mu m). In contrast, dissolved dyes are not taken up by any of these cells or 3D structures. The distribution of fluorescent ultrasmall gold nanoparticles inside cells, spheroids, and gut organoids is examined by confocal laser scanning microscopy. Nanoparticles conjugated with the cytostatic drug doxorubicin and a fluorescent dye exhibit significantly greater cytotoxicity toward CT-26 tumor spheroids than equally concentrated dissolved doxorubicin, probably because they enter the interior of a spheroid much more easily than dissolved doxorubicin. Comprehensive analyses show that the cellular uptake of ultrasmall gold nanoparticles occurs by different endocytosis pathways.

Automated summary

Ultrasmall gold nanoparticles are capable of penetrating intestinal cells, colorectal cancer cells, and related 3D structures, while dissolved dyes cannot be taken up by these cells or structures. The cellular uptake of ultrasmall gold nanoparticles is found to occur through different endocytosis pathways. The nanoparticles conjugated with the cytostatic drug doxorubicin exhibit enhanced cytotoxicity against tumor spheroids.