Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Nanoscale 'stealth' probe slides into cell walls seamlessly, say Stanford engineers

A 'stealth' probe sits firmly fused into a cell membrane. The membrane is represented by the small blue spheres, with the hydrophobic portion inside shown by squiggly fine blue lines. The silicon part of the probe is black and the chromium bands that bound the thin gold band are silver-gray. The gold band is obscured by the carbon atoms that are attached to it and that integrate with the hydrophobic part of the membrane. Benjamin Almquist
A 'stealth' probe sits firmly fused into a cell membrane. The membrane is represented by the small blue spheres, with the hydrophobic portion inside shown by squiggly fine blue lines. The silicon part of the probe is black and the chromium bands that bound the thin gold band are silver-gray. The gold band is obscured by the carbon atoms that are attached to it and that integrate with the hydrophobic part of the membrane. Benjamin Almquist

Abstract:
Stanford engineers have created a nanoscale probe they can implant in a cell wall without damaging the wall. The probe could allow researchers to listen in on electrical signals within the cell. That could lead to a better understanding of how cells communicate or how a cell responds to medication. The probe could also provide a better way of attaching neural prosthetics and with modification, might be an avenue for inserting medication inside a cell.

By Louis Bergeron

Nanoscale 'stealth' probe slides into cell walls seamlessly, say Stanford engineers

Stanford, CA | Posted on April 2nd, 2010

A nanometer-scale probe designed to slip into a cell wall and fuse with it could offer researchers a portal for extended eavesdropping on the inner electrical activity of individual cells.

Everything from signals generated as cells communicate with each other to "digestive rumblings" as cells react to medication could be monitored for up to a week, say Stanford engineers.

Current methods of probing a cell are so destructive they usually only allow a few hours of observation before the cell dies. The researchers are the first to implant an inorganic device into a cell wall without damaging it.

The key design feature of the probe is that it mimics natural gateways in the cell membrane, said Nick Melosh, an assistant professor of materials science and engineering in whose lab the research was done. With modification, the probe might serve as a conduit for inserting medication into a cell's heavily defended interior, he said. It might also provide an improved method of attaching neural prosthetics, such as artificial arms that are controlled by pectoral muscles, or deep brain implants used for treating depression.

The 600-nanometer-long, metal-coated silicon probe has integrated so smoothly into membranes in the laboratory, the researchers have christened it the "stealth" probe.

"The probes fuse into the membranes spontaneously and form good, strong junctions there," Melosh said. The attachment is so strong, he said, "We cannot pull them out. The membrane will just keep deforming rather than let go of the probes."

Melosh and Benjamin Almquist, a graduate student in materials science and engineering, are coauthors of a paper describing the research published March 30 in Proceedings of the National Academy of Sciences. The paper is available online.

Up to now, poking a hole in a cell membrane has largely relied on brute force, Melosh said.

Current methods are destructive

"We can basically rip holes in the cells using suction, we can use high voltage to puncture holes in their membranes, both of which are fairly destructive," he said. "Many of the cells don't survive." That limits the duration of any observations, particularly electrical measurements of cell function.

The key to the probe's easy insertion - and the membrane's desire to retain it - is that Melosh and Almquist based its design on a type of protein naturally found in cell walls that acts as a gatekeeper, controlling which molecules are allowed in or out.

A cell membrane is essentially a walled fortress. Within the wall itself is a water-repellant, or hydrophobic, zone. Since almost all molecules in a living being are water soluble, the hydrophobic region acts as a barrier to keep the molecules from slipping through the cell wall. The only way in or out is via the specialized proteins that form bridges across the membrane.

Those "transmembrane" protein gateways match the architecture of the membrane, with a hydrophobic center section bounded by two water soluble, or hydrophilic, layers.

"What we have done is make an inorganic version of one of those membrane proteins, which sits in the membrane without disrupting it," Melosh said. "Now we can envision using it for doing our own gate keeping."

To build their probe, Melosh and Almquist appropriated nanofabrication methods from the semiconductor industry to make tiny silicon posts, the tips of which they coated with three thin layers of metal - a layer of gold between two of chromium - to match the sandwich structure of the membrane. They then coated the gold band with carbon molecules to render it hydrophobic; the chromium bands are naturally hydrophilic.

Overcame technical challenge

"Getting that hydrophobic band just a few nanometers in thickness was an incredible technical challenge," Melosh said. Applying such a thin layer to the tip of a probe only 200 nanometers in diameter was impossible using existing methods, so he and Almquist devised a new technique using metal deposition to create the thin band that was needed.

That carefully applied metal coating on the stealth probe could give researchers electrical access to the inside of a cell, where they might monitor the electrical impulses generated by various cellular activities, Melosh said. That, combined with the probe's stability in the membrane, could be a huge asset to studies of certain electrically excitable cells such as neurons, which send signals throughout the brain, spinal cord and other nerves.

A device called a "patch clamp" can be used to monitor those sorts of electrical signals among cells now, Melosh said, but in its current form, it is comparatively crude.

"You come in with it, touch it to the cell surface, apply suction and tear a hole in the cell to give you access," he said. "However, it is a fairly slow procedure that has to be done one cell at a time, and it kills the cell within an hour or so."

"If the stealth probe will give us a long-term patch clamp, we'll really be able to get the ability to watch these networks over long periods of time, perhaps up to a week," he said.

"Ideally, what you'd like to be able to do is have an access port through the cell membrane that you can put things in or take things out, measure electrical currents … basically full control," said Melosh. "That's really what we've shown - this is a platform upon which you can start building those kinds of devices."

The next step is to demonstrate the functionality of the probe in living cells. Almquist and Melosh are now working with human red blood cells and cervical cancer cells, as well as ovary cells from a species of hamster.

The National Science Foundation and Canon Inc. provided financial support for this research.

Aimee Miles, an intern at the Stanford News Service, contributed to this story.

####

About Stanford University
Located between San Francisco and San Jose in the heart of Silicon Valley, Stanford University is recognized as one of the world's leading research and teaching institutions.

For more information, please click here

Contacts:
Louis Bergeron
Stanford News Service
(650) 725-1944

Copyright © Stanford University

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

Materials for the next generation of electronics and photovoltaics: MacArthur Fellow develops new uses for carbon nanotubes October 21st, 2014

Special UO microscope captures defects in nanotubes: University of Oregon chemists provide a detailed view of traps that disrupt energy flow, possibly pointing toward improved charge-carrying devices October 21st, 2014

Super stable garnet ceramics may be ideal for high-energy lithium batteries October 21st, 2014

Could I squeeze by you? Ames Laboratory scientists model molecular movement within narrow channels of mesoporous nanoparticles October 21st, 2014

Possible Futures

Imaging electric charge propagating along microbial nanowires October 20th, 2014

Superconducting circuits, simplified: New circuit design could unlock the power of experimental superconducting computer chips October 18th, 2014

Nanocoatings Market By Product Is Expected To Reach USD 8.17 Billion By 2020: Grand View Research, Inc. October 15th, 2014

Perpetuus Carbon Group Receives Independent Verification of its Production Capacity for Graphenes at 140 Tonnes per Annum: Perpetuus Becomes the First Manufacturer in the Sector to Allow Third Party Audit October 7th, 2014

Academic/Education

First Canada Excellence Research Chair gets $10 million from the federal government for oilsands research at the University of Calgary: Federal government announces prestigious research chair to study improving oil production efficiency October 19th, 2014

Raytheon, UMass Lowell open on-campus research institute: Industry leader’s researchers to collaborate with faculty, students to move key technologies forward through first-of-its-kind partnership October 11th, 2014

SUNY Colleges of Nanoscale Science and Engineering and National Institute for Occupational Safety and Health Announce Expanded Partnership October 2nd, 2014

Yale University and Leica Microsystems Partner to Establish Microscopy Center of Excellence: Yale Welcomes Scientists to Participate in Core Facility Opening and Super- Resolution Workshops October 20 Through 31, 2014 September 30th, 2014

Nanomedicine

Detecting Cancer Earlier is Goal of Rutgers-Developed Medical Imaging Technology: Rare earth nanocrystals and infrared light can reveal small cancerous tumors and cardiovascular lesions October 21st, 2014

Design of micro and nanoparticles to improve treatments for Alzheimers and Parkinsons: At the Faculty of Pharmacy of the UPV/EHU-University of the Basque Country encapsulation techniques are being developed to deliver correctly and effectively certain drugs October 20th, 2014

Non-Toxic Nanocatalysts Open New Window for Significant Decrease in Reaction Process October 19th, 2014

European Commission opens the gate towards the implementation of Nanomedicine Translation Hub October 16th, 2014

Announcements

Special UO microscope captures defects in nanotubes: University of Oregon chemists provide a detailed view of traps that disrupt energy flow, possibly pointing toward improved charge-carrying devices October 21st, 2014

Super stable garnet ceramics may be ideal for high-energy lithium batteries October 21st, 2014

Could I squeeze by you? Ames Laboratory scientists model molecular movement within narrow channels of mesoporous nanoparticles October 21st, 2014

Detecting Cancer Earlier is Goal of Rutgers-Developed Medical Imaging Technology: Rare earth nanocrystals and infrared light can reveal small cancerous tumors and cardiovascular lesions October 21st, 2014

Nanobiotechnology

Crystallizing the DNA nanotechnology dream: Scientists have designed the first large DNA crystals with precisely prescribed depths and complex 3D features, which could create revolutionary nanodevices October 20th, 2014

Scientists Map Key Moment in Assembly of DNA-Splitting Molecular Machine: Crucial steps and surprising structures revealed in the genesis of the enzyme that divides the DNA double helix during cell replication October 15th, 2014

DNA nano-foundries cast custom-shaped metal nanoparticles: DNA's programmable assembly is leveraged to form precise 3D nanomaterials for disease detection, environmental testing, electronics and beyond October 10th, 2014

Charged graphene gives DNA a stage to perform molecular gymnastics October 9th, 2014

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





  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE