The specks are known as quantum dots or inorganic semiconductor nanocrystals. Measuring in millionths of a millimeter, these dots are so small that the addition or removal of electrons changes the properties of the dot. The team, including Electrical and Computer Engineering Professors Dan van der Weide and Robert Blick with researchers Sujatha Ramachandran and George Kumar, found that by applying voltages to a solution of quantum dots and membranes similar to those of living cells, the dots would be pressed into the membranes. The dots formed rings, which in turn acted as portals in the membranes. These artificial portals or pores could enable a method of investigating living systems by means of semiconductor technology that until now could be theorized but not directly observed.
"To get a feeling of why this is important, you have to understand that each of our cell membranes has specific pores in them that regulate the flow of ions in and out," says Blick. "Through these ions, your cells will build up electric potential and communicate with other cells. This is how signal transduction is performed in your body, but it is also how chemicals react with your body. When, for example, caffeine enters a cell it stimulates the opening and closing of these ion channels. What we've found is that these quantum dots can form artificial pores that enhance the flow of ions and which we can control from the outside via voltage."
Quantum dots can be encoded with different colors making them useful as fluorescent labels for staining cells. Their resistance to photobleaching and physical siz
Source:University of Wisconsin