Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UCSD chemists use tiny ’chaperones’ to direct molecules and nanoparticles in drop of liquid

08.11.2004


Chemists at the University of California, San Diego have developed a method that uses dust-sized chips of silicon to surround and precisely direct the motion of molecules, cells, bacteria and other miniscule objects within a tiny drop of liquid.


Smart dust particles self assembled on drops of oil in water. Photo Credit: Jamie Link, UCSD



Their development of these tiny silicon “chaperones,” detailed today in an advance online publication in a forthcoming issue of the journal Nature Materials, represents an important new achievement in the emerging field of “microfluidics,” in which new methods are sought to create, transport and experiment with ever smaller volumes of fluids.

Much as the development of smaller and smaller computer chips has transformed the electronics industry, the “smaller is better” movement of microfluidics is already beginning to pave the way for a new wave of developments in biotechnology and nanotechnology. One major problem now facing scientists in the biotechnology industry is how to handle tiny volumes of liquid containing precious samples of DNA, bacteria, viruses or other nano-sized particles without losing much of the samples.


“As the sample volume becomes smaller and smaller, the number of molecules that stick to the insides of a micropipette or any other kind of micro-channel becomes a significant fraction of the total number of molecules in the sample,” says Michael Sailor, a professor of chemistry and biochemistry who headed the UCSD effort. “This problem has spawned the idea of a ‘lab in a drop.’ A sphere has the lowest ratio of surface area to volume, so if a droplet containing the sample of interest can be manipulated without it coming into contact with the walls of its container, one can minimize the amount of material lost.”

The UCSD development took shape when Jason Dorvee, one of Sailor’s graduate students, added a magnetic iron oxide to microscopic chips of silicon fabricated in Sailor’s laboratory so that they could be easily moved about with a hand-held magnet. These tiny chips, developed several years ago by Sailor and Jamie Link, a graduate researcher in Sailor’s laboratory, are also known as “smart dust. “We call them ‘smart dust’ because their nanostructure can be engineered to give them rudimentary sensing, data processing, communication, and homing capabilities,” says Sailor, “Jason’s addition of magnetic properties allows us to direct their motion.”

Sailor and his group initially developed these microscopic sensors so they could be programmed to detect and surround specific objects like a drop of toxic chemical or a cancer cell. Their latest development now provides the scientists with the additional capability to control and move this assembly of particles and their cargo to specific areas for examination or experimentation. But of even greater importance, their method could be adapted for future industrial microfluidics processes to mix and even neutralize chemicals without the need for pumps, valves, channels or pipettes. “It’s a new way of doing microfluidics,” explains Dorvee. “With this system, you can transport tiny material suspended in water through oil efficiently without pumps and channels.”

Once he added the superparamagnetic iron oxide to the silicon to make them magnetic, Dorvee made one side of the smart dust hydrophobic, or water repelling, and the other side hydrophilic, or water loving. This process, developed last year by Link and Sailor, assured that the tiny smart dust chips would always spontaneously assemble on the outside of organic droplets, such as oil, immersed in water or water droplets immersed in oil. When the chips come into contact with different chemicals, small changes in the color of their surfaces, which are detectable using a spectrometer based on a modified digital camera, allow the scientists to remotely identify the specific chemicals encased by the smart dust.

In their experiments, the chemists were able to move these smart-dust-encased droplets with hand-held magnets precisely within liquid-filled Petri dishes. The researchers were also able to move the droplets magnetically into contact with a tiny capillary tube, where their contents could be drained, mixed with other chemicals, then refilled with a microsyringe. This capability, shown in the sequence of photos above, would be extremely useful for scientists handling tiny volumes of valuable biological molecules or for any number of future industrial microfluidics processes. “We can manipulate material that wouldn’t normally be affected by magnetic fields, such as organic and inorganic solutions, cells, DNA and proteins,” says Dorvee.

To demonstrate how the magnetic silicon chaperones could be used to perform chemistry on a miniscule scale, Dorvee encased two tiny droplets with the smart dust, one containing a solution of potassium iodide and another containing a solution of silver nitrate, in a hydrophilic organic solvent. With a spectrometer pointed at the surfaces of the two droplets, he identified the two compounds, then magnetically brought the droplets into contact. This resulted in a chemical reaction that produced silver iodide, which he was again able to identify remotely from the color changes on the surface of the chips. “With the smart dust chaperones, we can actually make little microbottles that not only contain specific chemicals, but that we can identify with a label,” says Dorvee.

Other coauthors of the paper besides Sailor and Dorvee were Sangeeta Bhatia, an associate professor of bioengineering at UCSD’s Jacobs School of Engineering, and Austin Derfus, a graduate student working in her laboratory. The project was supported by grants from the Air Force Office of Scientific Research and the National Cancer Institute.

Kim McDonald | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Life Sciences:

nachricht Mass spectrometry sheds new light on thallium poisoning cold case
14.12.2018 | University of Maryland

nachricht Protein involved in nematode stress response identified
14.12.2018 | University of Illinois College of Agricultural, Consumer and Environmental Sciences

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Data use draining your battery? Tiny device to speed up memory while also saving power

14.12.2018 | Power and Electrical Engineering

Tangled magnetic fields power cosmic particle accelerators

14.12.2018 | Physics and Astronomy

In search of missing worlds, Hubble finds a fast evaporating exoplanet

14.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>