Usually various types of coatings are protecting the quantum dot core from degradation and release of e.g. toxic cadmium ions. However, the acidic environment in the stomach is able to degrade such coatings so that toxic components might be released


Biomedical applications for Quantum Dots, including in vivo imaging or drug delivery, require their targeting to the correct position in the body (see also the article on “behaviour inside the body”). This targeting can be achieved by specific coatings. However these coatings have been shown to degrade in acidic environments thereby releasing toxic cadmium ions (see also the article on “exposure - in vitro”). Degradation could thus occur either in intracellular compartments like lysosomes or in organs like the stomach. Therefore administration of Quantum Dots is largely restricted to intravenous injection. Nevertheless a very recent report addresses the biodistribution and stability of Quantum Dots in the digestive tract of the mouse after oral administration [1].

Scientists introduced a new surface coating for core-shell-shell Quantum Dots (CdSe-CdS-ZnS) that consists of a combination of polythiol-ligands and a silica shell. This modification renders these particles resistant to strong acidic solutions both in vitro and in vivo in the digestive tract of mice after oral administration [1]. The authors conclude, that the new coating offers the possibility to use Quantum Dots for the study of in vivo processes within the digestive system.




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