Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Weighing particles at the attogram scale

The illustration shows a suspended nanochannel resonator (SNR), which can directly measure the mass of individual nanoparticles with single-attogram precision. The inset shows a depiction from inside the embedded fluidic channel, while a DNA-origami gold nanoparticle assembly is passing through the resonator.
Image courtesy of Selim Olcum and Nate Cermak
The illustration shows a suspended nanochannel resonator (SNR), which can directly measure the mass of individual nanoparticles with single-attogram precision. The inset shows a depiction from inside the embedded fluidic channel, while a DNA-origami gold nanoparticle assembly is passing through the resonator.

Image courtesy of Selim Olcum and Nate Cermak

Abstract:
MIT engineers have devised a way to measure the mass of particles with a resolution better than an attogram — one millionth of a trillionth of a gram. Weighing these tiny particles, including both synthetic nanoparticles and biological components of cells, could help researchers better understand their composition and function.

Weighing particles at the attogram scale

Cambridge, MA | Posted on January 13th, 2014

The system builds on a technology previously developed by Scott Manalis, an MIT professor of biological and mechanical engineering, to weigh larger particles, such as cells. This system, known as a suspended microchannel resonator (SMR), measures the particles' mass as they flow through a narrow channel.

By shrinking the size of the entire system, the researchers were able to boost its resolution to 0.85 attograms —more than a 30-fold improvement over the previous generation of the device.

"Now we can weigh small viruses, extracellular vesicles, and most of the engineered nanoparticles that are being used for nanomedicine," says Selim Olcum, a postdoc in Manalis' lab and one of the lead authors of a paper describing the system in this week's issue of the Proceedings of the National Academy of Sciences.

Graduate student Nathan Cermak is also a lead author of the paper, and Manalis, a member of MIT's Koch Institute for Integrative Cancer Research, is the paper's senior author. Researchers from the labs of MIT professors and Koch Institute members Angela Belcher and Sangeeta Bhatia also contributed to the study.

A small sensor for small particles

Manalis first developed the SMR system in 2007 to measure the mass of living cells, as well as particles as small as a femtogram (one quadrillionth of a gram, or 1,000 attograms). Since then, his lab has used the device to track cell growth over time, measure cell density, and measure other physical properties, such as stiffness.

The original mass sensor consists of a fluid-filled microchannel etched in a tiny silicon cantilever that vibrates inside a vacuum cavity. As cells or particles flow through the channel, one at a time, their mass slightly alters the cantilever's vibration frequency. The mass of the particle can be calculated from that change in frequency.

To make the device sensitive to smaller masses, the researchers had to shrink the size of the cantilever, which behaves much like a diving board, Olcum says. When a diver bounces at the end of a diving board, it vibrates with a very large amplitude and low frequency. When the diver plunges into the water, the board begins to vibrate much faster because the total mass of the board has dropped considerably.

To measure smaller masses, a smaller "diving board" is required. "If you're measuring nanoparticles with a large cantilever, it's like having a huge diving board with a tiny fly on it. When the fly jumps off, you don't notice any difference. That's why we had to make very tiny diving boards," Olcum says.

In a previous study, researchers in Manalis' lab built a 50-micron cantilever — about one-tenth the size of the cantilever used for measuring cells. That system, known as a suspended nanochannel resonator (SNR), was able to weigh particles as light as 77 attograms at a rate of a particle or two per second.

The cantilever in the new version of the SNR device is 22.5 microns long, and the channel that runs across it is 1 micron wide and 400 nanometers deep. This miniaturization makes the system more sensitive because it increases the cantilever's vibration frequency. At higher frequencies, the cantilever is more responsive to smaller changes in mass.

The researchers got another boost in resolution by switching the source for the cantilever's vibration from an electrostatic to a piezoelectric excitation, which produces a larger amplitude and, in turn, decreases the impact of spurious vibrations that interfere with the signal they are trying to measure.

With this system, the researchers can measure nearly 30,000 particles in a little more than 90 minutes. "In the span of a second, we've got four or five particles going through, and we could potentially increase the concentration and have particles going through faster," Cermak says.

Particle analysis

To demonstrate the device's usefulness in analyzing engineered nanoparticles, the MIT team weighed nanoparticles made of DNA bound to tiny gold spheres, which allowed them to determine how many gold spheres were bound to each DNA-origami scaffold. That information can be used to assess yield, which is important for developing precise nanostructures, such as scaffolds for nanodevices.

The researchers also tested the SNR system on biological nanoparticles called exosomes — vesicles that carry proteins, RNA, or other molecules secreted by cells — which are believed to play a role in signaling between distant locations in the body.

They found that exosomes secreted by liver cells and fibroblasts (cells that make up connective tissue) had different profiles of mass distribution, suggesting that it may be possible to distinguish vesicles that originate from different cells and may have different biological functions.

The researchers are now investigating using the SNR device to detect exosomes in the blood of patients with glioblastoma (GBM), a type of brain cancer. This type of tumor secretes large quantities of exosomes, and tracking changes in their concentration could help doctors monitor patients as they are treated.

Glioblastoma exosomes can now be detected by mixing blood samples with magnetic nanoparticles coated with antibodies that bind to markers found on vesicle surfaces, but the SNR could provide a simpler test.

"We're particularly excited about using the high precision of the SNR to quantify microvesicles in the blood of GBM patients. Although affinity-based approaches do exist for isolating subsets of microvesicles, the SNR could potentially provide a label-free means of enumerating microvesicles that is independent of their surface expression," Manalis says.

###

The research was funded by the U.S. Army Research Office through the Institute for Collaborative Biotechnologies, the Center for Integration of Medicine and Innovative Technology, the National Science Foundation, and the National Cancer Institute.

Written by Anne Trafton, MIT News Office

####

For more information, please click here

Contacts:
Sarah McDonnell

617-253-8923

Copyright © Massachusetts Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Switching with molecules: Molecular switch will facilitate the development of pioneering electro-optical devices May 25th, 2018

Tunable diamond string may hold key to quantum memory: A process similar to guitar tuning improves storage time of quantum memory May 24th, 2018

Remote control of transport through nanopores: New study outlines key factors affecting the transfer of molecules through biological channels May 24th, 2018

2018 Kavli Prizes in Astrophysics, Nanoscience, and Neuroscience to be Announced Live on May 31: Live announcement at the Norwegian Academy of Science and Letters to be streamed live at World Science Festival Event May 24th, 2018

Govt.-Legislation/Regulation/Funding/Policy

Tunable diamond string may hold key to quantum memory: A process similar to guitar tuning improves storage time of quantum memory May 24th, 2018

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

NIST Puts the Optical Microscope Under the Microscope to Achieve Atomic Accuracy May 22nd, 2018

Magnesium magnificent for plasmonic applications: Rice University, University of Cambridge synthesize and test nanoparticles of abundant material May 22nd, 2018

Nanomedicine

Remote control of transport through nanopores: New study outlines key factors affecting the transfer of molecules through biological channels May 24th, 2018

New blood test rapidly detects signs of pancreatic cancer May 17th, 2018

Elastic microspheres expand understanding of embryonic development and cancer cells May 15th, 2018

Nanomedicine -- Targeting cancer cells with sugars May 14th, 2018

Discoveries

Switching with molecules: Molecular switch will facilitate the development of pioneering electro-optical devices May 25th, 2018

Tunable diamond string may hold key to quantum memory: A process similar to guitar tuning improves storage time of quantum memory May 24th, 2018

Remote control of transport through nanopores: New study outlines key factors affecting the transfer of molecules through biological channels May 24th, 2018

'Spooky action at a distance': Researchers develop module for quantum repeater May 23rd, 2018

Announcements

Switching with molecules: Molecular switch will facilitate the development of pioneering electro-optical devices May 25th, 2018

Tunable diamond string may hold key to quantum memory: A process similar to guitar tuning improves storage time of quantum memory May 24th, 2018

Remote control of transport through nanopores: New study outlines key factors affecting the transfer of molecules through biological channels May 24th, 2018

2018 Kavli Prizes in Astrophysics, Nanoscience, and Neuroscience to be Announced Live on May 31: Live announcement at the Norwegian Academy of Science and Letters to be streamed live at World Science Festival Event May 24th, 2018

Tools

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

NIST Puts the Optical Microscope Under the Microscope to Achieve Atomic Accuracy May 22nd, 2018

Self-assembling 3D battery would charge in seconds May 22nd, 2018

A micro-thermometer to record tiny temperature changes May 15th, 2018

Military

Tunable diamond string may hold key to quantum memory: A process similar to guitar tuning improves storage time of quantum memory May 24th, 2018

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

Hematene joins parade of new 2D materials: Rice University-led team extracts 3-atom-thick sheets from common iron oxide May 8th, 2018

Engineered polymer membranes could be new option for water treatment May 6th, 2018

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project