Ultrafiltration Method to Aid Genomics Research

Researchers have developed an ultrafiltration method, based on polycarbonate membranes etched with uniform 10 nanometer pores, to sort mixtures of macromolecules such as proteins or DNA in genomics research. Details on the methodology were reported in the June 11, 2002, issue of Langmuir.

The pores are lined with a thin layer of gold and then with another layer of thiol molecules. The thiol molecules spontaneously arrange themselves into a membrane one molecule deep, all molecules oriented in the same direction. The thiols contain a sulfur atom at one end and an acidic region at the other end. The sulfur allows the thiol to adhere to the gold layer while the acidic end is exposed to interact with the external medium. The final pores are less than nine nanometers wide.

The researchers, at the University of California, Davis (USA), found that by changing the pH on either side of the membrane, they could "open” or "close” the pores to different proteins even of similar size, using a method called electrostatic screening.

"The switchable technology will be important for transport on the nano-scale, particularly for nano- and micro-sensing, analysis on a chip, and micro-fluidic devices,” said Dr. Pieter Stroeve of the chemical engineering and materials science department. "Another application could be in controlled drug release, supplying drugs over a period of time when the body needs it.”



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