They’ve shrunk the Western blot!
December 3, 2012 § 4 Comments
Some of the best ideas come from chance conversations. It happened to Amy Herr at the University of California, Berkeley. A chat with a biologist colleague five years ago gave her an idea to improve a workhorse of molecular biology: Western blotting. This week, she and Alex Hughes report in the Proceedings of the National Academy of Science a special device that carries out 48 Western blots at once in an hour or less.
Analytical chemists have been eyeing Western blotting, developed in the 1970s, as a method that could use some updating (see a story I did on the subject earlier this year in ASBMB Today). Conventional Western blotting, as any graduate student or postdoc in the life sciences can attest, is time consuming, labor intensive and is unable to handle too many samples at once.
Herr noticed the need to improve Western blotting when chatting with her colleague. “She mentioned offhand that she had thousands of longitudinal biospecimens, collected over 25 to 30 years, that she would love to probe for specific protein markers, but there was no way she could do that, given time, funding and personnel limitations,” recalls Herr. “This really struck me: There was a clear unmet need to increase Western blotting’s throughput and perhaps even improve its performance.”
Herr’s expertise is in microfluidics, an area of research that exploits the flow of nanoliter volumes of fluids or less in microfabricated platforms that have channels, wells and reservoirs on the micron scale. The allure of microfluidics is that it uses very little sample and reagents, works very quickly and, because of the micron sizes, fits more experiments into one device, increasing sample throughout.
Hughes and Herr exploited microfluidics to develop a miniturized version of Western blotting that consisted of 48 microfluidic channels lined up on a standard microscope slide. All the steps of Western blotting happen in those channels. There isn’t a manual blotting step. The separated proteins don’t need to be out of the channels. With the device designed by Hughes and Herr, the proteins, once separated by size inside the channels, are efficiently captured inside of the channels. They are then probed with antibodies within the confines of the channels.
The investigators tested their device on analyses of human sera and cell lysates and established, in addition to the quick turnaround time, that the device had a detection limit of 50 pM and could quantify proteins over a 3.6-log dynamic range.The investigators showed that they could probe for three proteins simultaneously but hope to eventually expand the probing capacity to 15.
Hughes and Herr also made sure that their device didn’t require any special bits and pieces to work. “We hijacked a standard electrophoresis power supply to operate the assay,” says Herr. “We wanted to use common equipment and reagents. We did not want to develop a complex, in other words, costly, system that researchers would need as a package. We wanted to use, as much as possible, instruments and reagents that are already in a life scientist’s lab or is already commercially available.”
On this front, Herr says, they are actively working with life scientists to make sure that biologists can easily use this new take on an old technology.