Wednesday, August 31, 2011

Researchers Expand Capabilities Of Miniature Analyzer For Complex Samples

It’s not often that someone can claim that going from a positive to a negative is a step forward, but that’s the case for a team of scientists from the National Institute of Standards and Technology (NIST) and private industry. 

In a recent paper,* the group significantly extended the reach of their novel microfluidic system for analyzing the chemical components of complex samples. The new work shows how the system, meant to analyze real-world, crude mixtures such as dirt or whole blood, can work for negatively charged components as well as it has in the past for positively charged ones.

Illustration of a GEMBE device: a complex biological sample such as dissolved dirt or whole blood is pushed by an electric field toward a microchannel. Buffer fluid flowing in the opposite direction acts as a gate. Gradually reducing the bufffer flow slowly 'opens' the gate, allowing individual components from the sample to enter the microchannel when the pressure becomes weaker than the electric force pushing each component molecule. These molecules then travel past a detector that analyzes them. Unwanted components are kept out of the microchannel.
Credit: Strychalsi, NIST

In previous work,** NIST researchers Elizabeth Strychalski and David Ross, in collaboration with Alyssa Henry of Applied Research Associates Inc. (Alexandria, Va.), demonstrated the use of a technique called GEMBE (for “gradient elution moving boundary electrophoresis”) for analyzing complex samples. The NIST-developed system combines a simple microfluidic structure (two reservoirs connected by a microchannel), electrophoresis (which uses electricity to move sample components through a fluid) and pressure-driven flow.

Analyzing complex samples can be difficult because components in these samples (such as the fat globules in milk or proteins in blood) can “foul” or contaminate microfluidic channels. The traditional solution has been to remove contaminants with costly, time-consuming sample preparation prior to analysis.

GEMBE solves this problem by pumping fluid through the microchannel using a controlled pressure in the direction opposite to electrophoresis. This opposing pressure-driven flow acts as a "fluid gate" between the sample reservoir and the microchannel. Gradually reducing the pressure of the counterflow opens the "gate" a little bit at a time. 

A specific sample component is detected when the pressure flow becomes weak enough—i.e. the "gate" opens wide enough—that the component’s electrophoretic motion pushes it against the pressure-driven flow and into the channel for detection. In this way, different components enter the channel at different times, based on their particular electrophoretic motion. Most importantly, the channel doesn’t become fouled because the unwanted components in the sample are held out.

“Previously, we validated the GEMBE technique by quantitatively analyzing components from complex samples in solution that were cationic [positively charged] and could, therefore, be separated relatively easily from anionic [negatively charged] contaminants in a mixture,” Strychalski says. “However, we needed a way to make GEMBE work when both the desired components and the contaminants are negatively charged.”

For some samples, Strychalski says, this was achieved by choosing a different solution pH to change the electrophoretic motion of the unwanted components. In other cases, the addition of commercially available surface coatings to the sample did the trick without compromising the ease and robustness of the GEMBE technique.

“Additives can be selected that will interact with material in the sample that we don’t want to study,” Strychalski explains. “If we choose the right coating, it will slow the electrophoretic motion of contaminants relative to the desired components. This prevents the former from interfering with analysis while still allowing the latter to enter the microchannel for detection.”

Strychalski and her colleagues plan to continue refining the GEMBE system, including an effort to define which surface coatings optimize the technique for specific components in a variety of complex samples.
Contacts and sources:
Michael E. Newman
NIST

* E.A. Strychalski, A.C. Henry and D. Ross. Expanding the capabilities of microfluidic gradient elution moving boundary electrophoresis for complex systems. Analytical Chemistry, Vol. 83, No. 16, pp 6316–6322. Aug. 15, 2011.
** See “‘No Muss, No Fuss’ Miniaturized Analysis for Complex Samples Developed” in NIST Tech Beat, Nov. 17, 2009, at www.nist.gov/public_affairs/tech-beat/tb20091117.cfm#gembe.

4 comments:

  1. I found out, that taking herbal treatment is the best to get rid of hpv as soon as i feel the symptoms of hpv is appearing, i took the healing process by contacting Dr onokun for natural treatment it works wonders, amazingly ever since I had the herbal treatment i have not feel these horrible disease anymore and my doc told me the virus is gone, i am glad i finally got cured out from this horrible disease. every hpv or herpes patients should also get in touch with this herbalist Dr to get ride of these disease forever his email address;
    dronokunherbalcure@gmail.com..........he also specialize on the following details.

    HIV/AID
    HERPES 1/2
    CANCER

    ReplyDelete
  2. Investing online has been a main source of income,that's why knowledge plays a very important role in humanity,you don't need to over work yourself for money.All you need is the right information,and you could build your own wealth from the comfort of your home!Binary trading is dependent on timely signals,assets or controlled strategies which when mastered increases chance of winning up to 90%-100% with trading. It’s possible to earn $10,000 to $20,000 trading weekly-monthly,just file a complaint with  Robert,I had almost given up on everything about binary trading and ever getting my lost funds back,till i met with him,with his help now i have my lost funds back to my bank account and I can now trade successfully with his profitable strategies and software!! Email: Robertseaman939@gmail.com or Fb.me/investandmakemoney1 or  whatsApp: +44 7466 770724

    ReplyDelete
  3. I was diagnosed of herpes virus, I have tried all possible means to get cure but all my effort proved abortive, until a friend of mine introduced me to a herbal doctor called Dr Agaba, who prepare herbal medicine to cure all kind of diseases including herpes virus (Herpes), when i contacted this herbal doctor via email, he sent me herpes virus herbal medicine via courier service, when i received the herbal medicine he gave me step by step instructions on how to apply it, when i applied it as instructed i was totally cured from the virus within 3 weeks of usage. Contact this great herbal doctor today to get your cure. 
    Via Email: Dragabasolutionhome@gmail.com or WhatApp: +2349074536486

    ReplyDelete
  4. I has suffered for Human papillomavirus HPV) for 2years, I was given some tablets at the hospital but I refused to take it, They said I have to be on it for life so I don't want take a drugs everyday for life. No point in taking medicine everyday when u won't get cure from it and I was advice to seek for natural herbal cure, after some time I found dr onokun is the most trustful herbalist that have herbs to cure wicked symptom's,I emailed dr onokun, for 2weeks been his patient he cured my (HPV) with his herbal. I only used his natural herbs for two weeks it was 100% cure. I'm not (HPV) patient anymore. I'm happy about it i finally got cured out of this mess been in my body for 2years. I also recommend you if you're living with (HPV) or herpes symptoms i also want you to be free contact dr onokun with the email attach to my post. Dronokunherbalcure@gmail.com

    ReplyDelete