Tuesday, August 23, 2011


Molecular biosensor can monitor stress to cells by color changes

A nanoscale sensor that indicates mechanical stress on cells by a color change has been developed by University of Pennsylvania and Duke University bioengineers and chemists.

The researchers embedded light-emitting porphyrin pigment molecules in polymersomes, artificially engineered capsules that can carry a molecular payload in their hollow interiors.

When a stress is put on the membrane of these polymersomes molecules in a confined environment, the porphyrin molecular rotation changes, which changes the wavelength (color) it emits. The researchers calibrated the polymersomes by subjecting them to several kinds of controlled stresses — tension and heat, among others — and measuring their color changes.

For example, the labeled polymersomes could be injected into the bloodstream as a proxy for red blood cells. As blood cells and polymersomes travel through an arterial blockage, for example, scientists would be able to better understand what happens to the blood cell membranes by making inferences from the stress label measurements.

The porphyrin labeling system could also be integrated into medicine-carrying polymersomes to monitor drug delivery, for example, to indicate how much of a drug has come out.

The same stress-labeling technique could be applied directly to naturally occurring tissues, the researchers said.

Source: http://goo.gl/y6el7



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