Featured Research

from universities, journals, and other organizations

Speed of single-molecule measurements greatly increased

Date:
March 18, 2012
Source:
University of Pennsylvania
Summary:
Engineers have devised a way to measure nanopores -- tiny holes in a thin membrane that can detect single biological molecules such as DNA and proteins -- with less error than can be achieved with commercial instruments. They've miniaturized the measurement by designing a custom integrated circuit using commercial semiconductor technology.

This is a photograph of the Columbia Engineering team's custom multichannel CMOS preamplifier chip, attached to a circuit board with thin gold wirebonds.
Credit: Columbia Engineering

As nanotechnology becomes ever more ubiquitous, researchers are using it to make medical diagnostics smaller, faster and cheaper in order to better diagnose diseases, learn more about inherited traits and more. But as sensors get smaller, measuring them becomes more difficult; there is always a tradeoff between how long any measurement takes to make and how precise it is. And when a signal is very weak, the tradeoff is especially big.

Marija Drndić, an associate professor in the Department of Physics and Astronomy in the University of Pennsylvania School of Arts and Sciences, worked with a team of researchers at Columbia University's engineering school, led by Ken Shepard, to figure out a way to measure using nanopores, tiny holes in a thin membrane that can detect single biological molecules such as DNA and proteins, with less error than can be achieved with commercial instruments.

Their research was published in the journal Nature Methods.

Scientists are interested in nanopores because they may lead to extremely low-cost and fast DNA sequencing. But the signals from nanopores are very weak, so it is critically important to measure as cleanly as possible. In their study, the researchers miniaturized the measurement by designing a custom-integrated circuit using commercial semiconductor technology, building the nanopore measurement around the new amplifier chip.

"While most groups are trying to slow down DNA, our approach is to build faster electronics," Drndić said. "We combined the most sensitive electronics with the most sensitive solid-state nanopores."

"We put a tiny amplifier chip directly into the liquid chamber next to the nanopore, and the signals are so clean that we can see single molecules passing through the pore in only one microsecond," said Jacob Rosenstein, a Ph.D. candidate in electrical engineering at Columbia and lead author of the paper. "Previously, scientists could only see molecules that stay in the pore for more than 10 microseconds."

Many single-molecule measurements are currently made using optical techniques, which use fluorescent molecules that emit photons at a particular wavelength. But, while fluorescence is very powerful, its major limitation is that each molecule usually produces only a few thousand photons per second.

"This means you can't see anything that happens faster than a few milliseconds, because any image you could take would be too dim," Columbia Engineering's Shepard said. "On the other hand, if you can use techniques that measure electrons or ions, you can get billions of signals per second. The problem is that for electronic measurements there is no equivalent to a fluorescent wavelength filter, so, even though the signal comes through, it is often buried in background noise."

Shepard's group has been interested in single-molecule measurements for several years looking at a variety of novel transduction platforms. They began working with nanopore sensors after Drndic gave a seminar at Columbia Engineering in 2009.

"We saw that nearly everybody else measures nanopores using classical electrophysiology amplifiers, which are mostly optimized for slower measurements," Shepard said. "So we designed our own integrated circuit instead."

Rosenstein designed the new electronics and did much of the lab work. Drndić's group fabricated the nanopores that the team then measured in their new system.

"It's very exciting to be able to make purely electronic measurements of single molecules," Rosenstein said. "The setup for nanopore measurements is very simple and portable. It doesn't require a complicated microscope or high-powered instruments; it just requires attention to detail. You can easily imagine nanopore technology having a major impact on DNA sequencing and other medical applications within the next few years."

This research was funded by the National Institutes of Health, the Semiconductor Research Corporation and the Office of Naval Research.


Story Source:

The above story is based on materials provided by University of Pennsylvania. Note: Materials may be edited for content and length.


Journal Reference:

  1. Jacob K Rosenstein, Meni Wanunu, Christopher A Merchant, Marija Drndic, Kenneth L Shepard. Integrated nanopore sensing platform with sub-microsecond temporal resolution. Nature Methods, 2012; DOI: 10.1038/nmeth.1932

Cite This Page:

University of Pennsylvania. "Speed of single-molecule measurements greatly increased." ScienceDaily. ScienceDaily, 18 March 2012. <www.sciencedaily.com/releases/2012/03/120318143912.htm>.
University of Pennsylvania. (2012, March 18). Speed of single-molecule measurements greatly increased. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2012/03/120318143912.htm
University of Pennsylvania. "Speed of single-molecule measurements greatly increased." ScienceDaily. www.sciencedaily.com/releases/2012/03/120318143912.htm (accessed July 25, 2014).

Share This




More Matter & Energy News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins