Welcome To Iconocast

How to add a URL link from your web site to the Iconocast web sites

Virtual tour of Southern California

Recent News and Articles on the Keywords: dna + sieve + tiny  Related to the article below (Last Update: 8/5/2008)

Sky News Police 'exaggerated DNA evidence against McCanns' Belfast Telegraph, United Kingdom - 51 minutes ago Madeleine McCann's parents are accusing the Portuguese police of exaggerating DNA evidence gathered during the investigation into their daughter's ... Madeleine McCann: Portuguese detectives lied to Gerry McCann about ... Telegraph.co.uk Scientist?s McCann DNA warning Aberdeen Press and Journal Kate McCann's Interview Silence Sky News The Herald - Telegraph.co.uk all 603 news articles » Canada.com Foot washed ashore is human, authorities say Seattle Post Intelligencer - Peregrin said the foot would be sent for a forensic investigation and a DNA profile. Results of a DNA profile would take six to eight weeks, he said. ... Shoe containing human foot found on Wash. beach The Associated Press Remains found in shoe are human, officials say Seattle Times Bones In Shoe Found On Washington Beach Are From Human Gant Daily Mirror.co.uk - ToTheCenter.com all 399 news articles » Brian Dugan's lawyers to get DNA reports in Jeanine Nicarico ... Chicago Tribune, United States - Brian Dugan's defense attorneys will be allowed to study thousands of records from DNA labs that provided evidence for the defendant's pending trial in the ... Briefs: Dugan defense gets access Chicago Daily Herald Motion filed in Dugan case ? but contents unknown Naperville Sun all 3 news articles » New York Daily News DNA fingered anthrax suspect News24, South Africa - Washington - DNA analysis of anthrax in victims' bodies led investigators to the government scientist who killed himself just before he was charged in the ... AssociatedPress WASHINGTON: DNA of victims led officials to suspect in anthrax attacks Detroit Free Press US man 'linked to anthrax by DNA' BBC News CNN - FOXNews all 5,274 news articles » DNA Testing and Genetic Profiles Help Avoid Broken Hearts Polls Reveal PR Web (press release), WA - The rapid growth in popularity of DNA testing and genetic profiling is proving many skeptics wrong. A recent poll shows that the benefits available from ... Judge: Test evidence for DNA Battle Creek Enquirer, MI - 38 minutes ago A Calhoun County Circuit Court judge has granted a defense request for DNA testing of evidence in a 1995 Bedford Township murder. ... Lawyers in Nicarico trial get DNA records Fort Mills Times, SC - CHICAGO ? Lawyers for the man accused in the 1983 abduction, rape and murder of a 10-year-old Naperville girl will get administrative reports from DNA labs ... News roundup: Hurricane watch; DNA used to identify anthrax spores USA Today - Other news websites are covering Tropical Storm Edouard, which is expected to hit the Gulf coast tomorrow morning. "A hurricane watch -- which means ... At Last...DNA Assessed Health and Wellness is Available and Making ... PR Web (press release), WA - DNA assessed health and wellness is finally available for everyone. No longer is state of the art technology in health and wellness only for the rich and ... Two Stanford Faculty Will Benefit from Keck Awards MarketWatch - Wysocka's work involves DNA--the threads made of four different molecular units variously arranged to encode the genes that make up all living organisms. ...

DNA sieve -- Nanoscale pores can be tiny analysis labs

Imagine being able to rapidly identify tiny biological molecules such as DNA and toxins using less than a drop of salt water in a system that can fit on a microchip. It's closer than you might believe, say a team of researchers at the National Institute of Standards and Technology (NIST), Brazil's Universidade Federal de Pernambuco, and Wright State University in Dayton, Ohio.

In a paper appearing next week in the Proceedings of the National Academy of Sciences,* the team proves for the first time that a single nanometer-scale pore in a thin membrane can be used to accurately detect and sort different-sized polymer chains (a model for biomolecules) that pass through or block the channel.

Article continues below and (thank you)

DNA Sieve -- Nanoscale Pores Can Be Tiny Analysis Labs

Caption: Graphic showing a lipid bilayer membrane (blue) with an alpha-hemolysin nanopore. A polyethylene glycol molecule (green globular structure) is transiting the pore; others are in solution on one side of the membrane. The colored spheres represent individual atoms, and are approximately 0.5 nanometers in diameter, or one twenty -thousandth the width of a human hair.

Credit: NIST

Usage Restrictions: None

Traditionally, unknown molecules are measured and identified using mass spectrometry, a process that involves ionizing and disintegrating large numbers of a target molecule, then analyzing the masses of the resulting molecules to produce a "molecular fingerprint" for the original sample. This equipment can cover a good-sized desk. By contrast, the "single-molecule mass spectrometry" system described in the PNAS paper is a non-destructive technique that in principle can measure one molecule at a time in a space small enough to fit on a single microchip device.

The technique involves creating a lipid bilayer membrane similar to those in living cells, and "drilling" a pore in it with a protein (alpha-hemolysin) produced by the Staphyloccoccus aureus bacteria specifically to penetrate cell membranes. Charged molecules (such as single-stranded DNA) are forced one-at-a-time into the nanopore, which is only 1.5 nanometers (the diameter of a human hair is about 10,000 nanometers) at its smallest point, by an applied electric current. As the molecules pass through the channel, the current flow is reduced in proportion to the size of each individual chain, allowing its mass to be easily derived.

In this experiment, various-sized chains in solution of the uncharged polymer polyethylene glycol (PEG) were substituted for biomolecules. Each type of PEG molecule reduced the nanopore's electrical conductance differently as it moved through, allowing the researchers to distinguish one size of PEG chain from another.

As a control, a solution of a highly purified PEG of a specific size was characterized with the nanopore. The resulting "fingerprint" closely matched the one identifying samples of the same size polymer in the mixed chain solution.

Further enhancement of the data from both the experimental and control tests yielded mass measurements and identifications of the different PEG chains that correlate with those made by traditional mass spectrometry.

Because the dimensions of the lipid bilayer and the alpha-hemolysin pore, as well as the required amount of electrical current, are at the nanoscale level, the "single-molecule mass spectrometry" technology may one day be incorporated into "lab-on-a-chip" molecular analyzers and single-strand DNA sequencers.

* J.W.F. Robertson, C.G. Rodriguez, V.M. Stanford, K.A. Rubinson, O.V. Krasilnikov and J.J. Kasianowicz. Single-moelcule mass spectrometry in solution using a solitary nanopore. Proceedings of the National Academy of Sciences 104 (20): 8207, May 15, 2007.