Former lab scientists' biosensor plays diverse role in drug research.(Business)

Byline: Start-ups By Dan Mayfield

Duncan McBranch and David Whitten have an unusual business challenge. Their product is so useful, they need to limit the market.

McBranch and Whitten founded QTL Biosystems LLC in Santa Fe late last year.

The former Los Alamos National Laboratory researchers invented a fluorescent biosensor that can detect viruses, proteins, DNA fragments and other compounds in minutes.

The patented biosensor, as yet unnamed, has so many uses, "One of the challenges for us is to narrow that down," McBranch says.

One use is in drug development, he says. Drug companies use slow, multistep tests to determine the …