( led Jurkat cells which are naturally n...)Berkeley researchers lay groundwork for cell version of DNA chip

Once it was established that cell surfaces could be coated with single-stranded DNA, Chandra worked with Douglas to demonstrate that this adhesion system could be used to attach cells to a non-biological surface. Douglas is a student under Mathies, director of UCB's Center for Analytical Biotechnology. Chandra and Douglas used a commercial chemical handle, the sulfur-based thiolate ion, to anchor single-stranded DNA onto gold pads, which were incorporated into microfluidic chips through standard photolithography. After the DNA-coated Jurkat cells were rinsed over the chips, fluorescence microscopy revealed that only those cells coated with single-stranded DNA complementary to the anchored DNA adhered to the gold pads. Cells that were otherwise identical but bearing mismatched DNA sequences were washed away.

"The adhesion of cells is very quick and far stronger than will be needed for most applications," said Chandra. "We just let them incubate for 35 minutes, rinse, and we're ready to go. We've kept our cells alive on the chip for up to 25 hours and the same proportion of cells survive using our method as cells cultured under identical conditions."

The next step, Chandra said, is to develop procedures for making complex arrays of cells quickly. The researchers also need to demonstrate that devices based on this cell-adhesion system will be useful for high-throughput screening applications.