Scientists design simple dipstick test for cocaine, other drugs

November 13, 2006

Researchers at the University of Illinois at Urbana-Champaign have developed a simple "dipstick" test for detecting cocaine and other drugs in saliva, urine or blood serum. The test is based upon DNA-gold nanoparticle technology, and can be packaged in user-friendly kits similar to those used for home pregnancy tests.

"Building upon our earlier work with lead (Pb) sensors, we constructed colorimetric sensors that are based on the lateral flow separation of aptamer-linked nanostructures," said Yi Lu, a chemistry professor at the U. of I., and a researcher at the Beckman Institute for Advanced Science and Technology.

"The new sensors offer a quick and convenient test that can be utilized by first responders or emergency room staff to quickly screen individuals for a variety of drugs and other chemicals." Lu said.

Aptamers are single-stranded nucleic acids that can bind to specific molecules in three-dimensions. For each molecular target, such as cocaine, a corresponding aptamer can be selected from a large DNA library.

By using lateral flow devices as platforms to separate aptamer-linked nanoparticle aggregates, Lu, postdoctoral researcher Juewen Liu and graduate student Debapriya Mazumdar created highly sensitive and selective colorimetric sensors that mimic litmus paper tests. The researchers describe their work in a paper accepted for publication in the journal Angewandte Chemie International Edition.

"Our lateral flow devices take advantage of the difference in size between dispersed and aggregated gold nanostructures," Lu said. "This provides critical control for the performance of the devices."

The lateral flow device consists of four overlapping pads – wicking, conjugation, membrane and absorption. The appropriate aptamer-linked nanoparticle aggregates are placed on the conjugation pad, streptavidin is applied as a thin line to the membrane pad, and the device is then dried.

When dipped into a solution, or swabbed with a sample, the wicking pad carries the fluid to the nanoparticle aggregates on the conjugation pad. The rehydrated aggregates then migrate to the edge of the membrane, which they cannot penetrate because of their large size.

The aptamers quickly bind to any targeted molecules that are present, freeing some of the gold nanoparticles. The red-colored nanoparticles then migrate along the membrane, where they are captured by the streptavidin and form a red line. The intensity of the line is an indicator of how much of the targeted molecule was in the sample solution.

So far, the researchers have successfully demonstrated their dipstick technology on both adenosine (a nucleotide consisting of adenine and ribose) and cocaine, in human blood serum.

"Our results show that the aptamer-based dipstick is compatible with biological samples, making applications in medicinal diagnostics possible," Lu said.

Source: University of Illinois at Urbana-Champaign

3.8 /5 (19 votes)  

Rank 3.8 /5 (19 votes)
Tags

Relevant PhysicsForums posts
  • Stem cell question.
    createdFeb 10, 2012
  • Protease cleavage
    createdFeb 10, 2012
  • Pertubance in a model
    createdFeb 10, 2012
  • Cancer drugs and Alzheimer's, Oh my!
    createdFeb 09, 2012
  • Squishing cells
    createdFeb 09, 2012
  • Any books/articles for evolutionary stable strategy models in humans?
    createdFeb 09, 2012
  • More from Physics Forums - Biology

More news stories

New kind of solar cell could capture significantly more energy than current cells

New solar cells could increase the maximum efficiency of solar panels by over 25%, according to scientists from the University of Cambridge.

Nanotechnology / Nanophysics

created Feb 08, 2012 | popularity 4.5 / 5 (12) | comments 14 | with audio podcast

Nanoshell whispering galleries improve thin solar panels

Visitors to Statuary Hall in the U.S. Capitol Building may have experienced a curious acoustic feature that allows a person to whisper softly at one side of the cavernous, half-domed room and for another on ...

Nanotechnology / Nanomaterials

created Feb 07, 2012 | popularity 4.3 / 5 (6) | comments 6 | with audio podcast

'Dark plasmons' transmit energy

Microscopic channels of gold nanoparticles have the ability to transmit electromagnetic energy that starts as light and propagates via "dark plasmons," according to researchers at Rice University.

Nanotechnology / Nanophysics

created Feb 09, 2012 | popularity 4.8 / 5 (9) | comments 1 | with audio podcast

Revealing how a battery material works

Since its discovery 15 years ago, lithium iron phosphate (LiFePO4) has become one of the most promising materials for rechargeable batteries because of its stability, durability, safety and ability to deliver ...

Nanotechnology / Nanomaterials

created Feb 08, 2012 | popularity 5 / 5 (5) | comments 0 | with audio podcast

Nanotube therapy takes aim at breast cancer stem cells

Wake Forest Baptist Medical Center researchers have again proven that injecting multiwalled carbon nanotubes (MWCNTs) into tumors and heating them with a quick, 30-second laser treatment can kill them.

Nanotechnology / Bio & Medicine

created Feb 09, 2012 | popularity 5 / 5 (1) | comments 0 | with audio podcast


Walney offshore wind farm is world's biggest (for now)

(PhysOrg.com) -- The Walney wind farm on the Irish Sea--characterized by high tides, waves and windy weather--officially opened this week. The farm is treated in the press as a very big deal as the Walney ...

GPS court ruling leaves US phone tracking unclear

A US Supreme Court decision requiring a warrant to place a GPS device on the car of a criminal suspect leaves unresolved the bigger issue of police tracking using mobile phones, legal experts say.

Europeans protest controversial Internet pact

Tens of thousands of people marched in protests in more than a dozen European cities Saturday against a controversial anti-online piracy pact that critics say could curtail Internet freedom.

Europe stakes billion-dollar bet on new rocket

A pencil-slim rocket is scheduled to lift into space from South America on Monday, carrying a billion-dollar bet that Europe can grab a juicy slice of the market to place satellites in low orbit.

Study finds that anti-diabetic medication can prevent the long-term effects of maternal obesity

In a study to be presented today at the Society for Maternal-Fetal Medicine's annual meeting, The Pregnancy Meeting, in Dallas, Texas, researchers will report findings that show that short therapy with the anti-diabetic medication ...

Netflix settlement trims 14 pct off 4Q earnings

(AP) -- Netflix pressed the rewind button on its fourth-quarter earnings after settling allegations that the video subscription service violated a consumer-privacy law.