Fluorescent polymer reveals deformation

The team of researchers led by Joris Sprakel, has designed this new kind of polymer that 'reports' its spatial configuration to the researchers through the light it emits. PhD candidate Hande Cingil carried out the work on the water-soluble semiconducting polymers, which the researchers have called conjugated polyelectrolytes (CPEs).

Luminescent polymers have existed for some time. They change colour as their conformation changes. A special feature of the CPE polymers is that nuances can be observed in these colour changes. Following irradiation with UV light, the existing polymers emit a colour spectrum that looks like the profile of a mountain with a flat top. But the new polymers have their own ‘fingerprint’: they show specific peaks in the spectrum. In addition, these peaks shift as the spatial structure changes, for example, if the material in which they are incorporated is stretched. As a result, the novel polymers can detect very small forces on the nanoscale.

The novel polymers can be used for many purposes. Groups of molecules can be attached to the polymers for specific applications, such as the detection of proteins or toxins. Thanks to the discovery it is possible to study changes in conformation, also deep inside complex substances and materials, in an entirely new way. For example, it offers an improved method for determining exactly how viral proteins stretch and fold to encapsulate DNA, or how very minor damage to polymeric materials gradually accumulates and eventually causes the materials to rupture. The researchers are currently working on fundamental research that goes beyond showing whether a polymer chain has stretched: they aim to show exactly where in the chain this stretching occurred.