Polymer Characterization 'Tweezers' Turn Nobel Theory İnto benchtop Tool

Researchers at UC Santa Barbara have developed a new and highly efficient way to characterize the structure of polymers at the nanoscale -- effectively designing a routine analytical tool that could be used by industries that rely on polymer science to innovate new products, from drug delivery gels to renewable bio-materials. Professor Omar Saleh and graduate student Andrew Dittmore of the UCSB Materials department have successfully measured the structure and other critical parameters of a long, string-like polymer molecule -- polyethylene glycol, or PEG -- by stretching it with an instrument called magnetic tweezers.

"We attach one end of the PEG molecule to a surface, and the other to a tiny magnetic bead, then pull on the bead by applying a magnetic field," explained Saleh. "The significance is that we're able to perform the elastic measurements -- force vs. length measurement -- to see aspects of polymer structure that are hard to see in any other way, and we can do it within minutes on a benchtop apparatus."

Their research to characterize this particular polymer will lay the groundwork for developing a screening tool that could be used by a number of industries, according to Saleh's research team.

"Our measurements of PEG can be used as a baseline for comparison to other polymers, including biomolecules such as DNA, RNA and proteins, which display more complex physics," said Dittmore. "We chose to study PEG because it is an inert polymer that is biocompatible, soluble in water, and used for many technological purposes. The protocols we developed will be useful for future work with a variety of polymers, greatly expanding the versatility of the magnetic tweezers technique."

PEG is one of the most frequently used polymers in creams, cosmetics, adhesives and medicines, but its application goes beyond everyday household products. As a coating, PEG can shield against an unwanted immune response to give a medicine a stealth-like quality. To this end, it is used to enhance the effectiveness of anticancer drugs by increasing the circulation time in the body. PEG repels other molecules and is often used as a nonfouling coating for biomedical implants and biosensors that detect the presence of drugs or antibodies in blood.