 |
 |
| Back Issues |
|
|
|
|
ACS Members can sign up to receive C&EN e-mail newsletter.  |
|
|
 Join ACS |
|
||||||||||||||
|
NANOTECHNOLOGY
Taking advantage of the fact that membranes can be designed to recognize, isolate, and transport a desired molecule out of a mixture, researchers at the University of Florida, Gainesville, have carried out chiral separations using an antibody-based nanotube membrane.
Using membranes prepared in this way, they successfully separated enantiomers of finrozole [Science, 296, 2198 (2002)]. The compound is being developed by Hormos Medical Corp., Turku, Finland, to treat lower urinary tract symptoms related to hormonal imbalance. "Exciting" is how Reginald M. Penner, a nanotechnology and materials chemistry expert at the University of California, Irvine, describes the Florida work. "The chiral resolution capability of the membrane system has the potential to change the way drugs are manufactured," he says. Christopher J. Welch, a process research fellow at Merck who runs a group that develops rapid separations of enantiomers, shares Penner's excitement. He adds that the Florida work "is a nice example of how materials science and nanotechnology together can create something with a lot of promise for actual separations." Finrozole has two chiral centers, making four stereoisomers possible: RR, SS, RS, and SR. A racemate consisting of the RS and SR enantiomers is in Phase II clinical trials.
Charles R. Martin, chemistry professor at the University of Florida, Gainesville In a U-tube setup, the membrane laced with RS-selective fragments transports the RS enantiomer up to 4.5 times faster than it does the SR enantiomer. Preferential transport increases as membrane pore size decreases. "As the pore diameter becomes smaller, analytes are forced into close proximity with the antibodies lining the wall," Penner explains. "The nanoscale dimension of the pores is essential to the membrane's operation." A problem often encountered with using antibodies as recognition elements in separations is that the tight binding between the antibody and the target prevents eventual release of the desired molecule. This problem is easily solved in the antibody-based membrane system through the addition of dimethylsulfoxide to the feed and receiver solutions, the Florida team shows. At the moment, productivity of the membranes is limited because throughput is low, Martin says. But he points out that, on the basis of his group's work on nanotube membrane separations, various ways to enhance throughput are available. |
||||||||||||||
|
Chemical & Engineering News |
||||||||||||||
|
||||||||
|
||||||||
|
||||||||
|
||||||||
|
||||||||
|
||||||||
