The aim of this work from the MESA+ Institute for Nanotechnology at the University of Twente in The Netherlands was to develop a drug nanovehicle that will have controllable properties: either deliver a drug via the blood stream to a specific location and then release it, or bring a drug to a location and have a controlled uptake of chemicals into the nanovehicle for a reaction inside and then release the content. Here’s what the scientists were able to achieve, as they reported in the September issue of Nature Materials:
By using polymers containing iron, it is possible to make intelligent containers of which the access of molecules can be regulated in a chemical way…
A true breakthrough in this research is the use of polymers having iron in their main chain. This is the material the containers are made of. By using iron, for the first time it is possible to adjust the permeability of the material via oxidation and reduction reactions. Scientist Mrs. Yujie Ma and Dr. Mark Hempenius, both of the group of Julius Vancso, succeeded in creating containers that can be opened and closed in this ‘chemical’ way. Oxidants or reductants take care of the access: the oxidant can be ironchloride, for example, a reductant could even be Vitamine C.
This selective access–one molecule gets in, the other won’t–is the result of the layered structure of the wall of the container. Polymer chains are layererd on top of each other and an electrostatic charge keeps them together. Influencing this charge with redox reactions, immediately influences the permeability of the wall. The container can contain a limited number of molecules, a soluble is already present inside.
As oxidation and reduction steps take part in numerous biochemical processes in water, the nanocontainers are useful for a variety of biological and biomedical applications. The scientists foresee applications in ‘green’ areas like food additives, medicine and cosmetics. In a more fundamental way, nanocontainers could be used in biochemistry to study large numbers of enzyme reactions at the same time and with high throughput.
Picture caption: Nanocapsules that didn’t let any molecules pass before,now admit molecules thanks to oxidation in their close proximity. In this way, a moveable reaction container is formed. In this case FeCl3 is used as an oxidant or ‘chemical doorman’ and a 4.4-kdalton dextran molecule can get in.