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Showing posts with label nanomotors. Show all posts
Showing posts with label nanomotors. Show all posts

February 12, 2014

Nanomotors are controlled, for the first time, inside living cells

A team of chemists and engineers at Penn State has placed tiny synthetic motors inside live human cells, propelled them with ultrasonic waves and steered them magnetically. It's not exactly "Fantastic Voyage," but it's close. The nanomotors, which are rocket-shaped metal particles, move around inside the cells, spinning and battering against the cell membrane.

The video shows a demonstration of very active gold nanorods internalized inside HeLa cells in an acoustic field. The video below was taken under 1000X magnification in the bright field, with most of the incoming light blocked at the aperture.

"As these nanomotors move around and bump into structures inside the cells, the live cells show internal mechanical responses that no one has seen before," said Tom Mallouk, Evan Pugh Professor of Materials Chemistry and Physics. "This research is a vivid demonstration that it may be possible to use synthetic nanomotors to study cell biology in new ways. We might be able to use nanomotors to treat cancer and other diseases by mechanically manipulating cells from the inside. Nanomotors could perform intracellular surgery and deliver drugs noninvasively to living tissues."





Optical microscope image of a HeLa cell containing several gold-ruthenium nanomotors. Arrows indicate the trajectories of the nanomotors, and the solid white line shows propulsion. Near the center of the image, a spindle of several nanomotors is spinning. Inset: Electron micrograph of a gold-ruthenium nanomotor. The scattering of sound waves from the two ends results in propulsion.

Image: Mallouk Lab/ Penn State Nanomotors are controlled,


February 01, 2013

Enzyme Molecules as Nanomotors

Enzymes, workhorse molecules of life that underpin almost every biological process, may have a new role as “intelligent” micro- and nanomotors with applications in medicine, engineering and other fields. That’s the topic of a report in the Journal of the American Chemical Society, showing that single molecules of common enzymes can generate enough force to cause movement in specific directions.

Peter J. Butler, Ayusman Sen and colleagues point out that enzymes — proteins that jump-start chemical reactions — are the basis of natural biological motors essential to life. Scientists long have wondered whether a single enzyme molecule, the smallest machine that could possibly exist, might be able to generate enough force to cause its own movement in a specific direction. “Positive answers to these questions,” they explain, “have important implications in areas ranging from biological transport to the design of ‘intelligent,’ enzyme-powered, autonomous nano- and micromotors, which are expected to find applications in bottom-up assembly of structures, pattern formation, cargo (drug) delivery at specific locations, roving sensors and related functions.”

They provide the positive answers in experiments with two common enzymes called catalase and urease. Catalase protects the body from harmful effects of hydrogen peroxide formed naturally in the course of life. Urease, found in many plants, converts urea to ammonia and carbon dioxide. The researchers show that these two enzymes, in the presence of their respective substrate (hydrogen peroxide or urea, which acts as fuel), show movement. More significantly, the movement becomes directional through the imposition of a substrate gradient, a form of chemotaxis. Chemotaxis is what attracts living things toward sources of food. The researchers also show that movement causes chemically interconnected enzymes to be drawn together; a form of predator-prey behavior at the nanoscale.




Using fluorescence correlation spectroscopy, researcher show that the diffusive movements of catalase enzyme molecules increase in the presence of the substrate, hydrogen peroxide, in a concentration-dependent manner. Employing a microfluidic device to generate a substrate concentration gradient, they show that both catalase and urease enzyme molecules spread toward areas of higher substrate concentration, a form of chemotaxis at the molecular scale. Using glucose oxidase and glucose to generate a hydrogen peroxide gradient, they induce the migration of catalase toward glucose oxidase, thereby showing that chemically interconnected enzymes can be drawn together.



July 06, 2010

Light-driven nanoscale plasmonic motors

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Nature Nanotechnology - Light-driven nanoscale plasmonic motors

A plasmonic motor only 100 nanometers in size when illuminated with linearly polarized light can generate a torque sufficient to drive a micrometre-sized silica disk 4,000 times larger in volume.

In addition to easily being able to control the rotational speed and direction of this motor, we can create coherent arrays of such motors, which results in greater torque and faster rotation of the microdisk

"When multiple motors are integrated into one silica microdisk, the torques applied on the disk from the individual motors accumulate and the overall torque is increased," Liu says. "For example, a silica disk embedded with four plasmonic nanomotors attains the same rotation speed with only half of the laser power applied as a disk embedded with a single motor." The nanoscale size of this new light mill makes it ideal for powering NEMS, where the premium is on size rather than efficiency. Generating relatively powerful torque in a nanosized light mill also has numerous potential biological applications, including the controlled unwinding and rewinding of the DNA double helix. When these light mill motors are structurally optimized for efficiency, they could be useful for harvesting solar energy in nanoscopic systems.

June 05, 2009

University of Florida has new Light Driven Nanomotors


Sunlight prompts a newly developed molecular nanomotor to unclasp in this artist’s illustration. In a paper expected to appear soon in the online edition of the journal Nano Letters, a team of researchers from the University of Florida reports building a new type of “molecular nanomotor” driven only by photons, or particles of light. While it is not the first photon-driven nanomotor, the almost infinitesimal device is the first built entirely with a single molecule of DNA – giving it a simplicity that increases its potential for development, manufacture and real-world applications in areas ranging from medicine to manufacturing, the scientists say.

In a paper expected to appear soon in the online edition of the journal Nano Letters, the University of Florida team reports building a new type of “molecular nanomotor” driven only by photons, or particles of light. While it is not the first photon-driven nanomotor, the almost infinitesimal device is the first built entirely with a single molecule of DNA — giving it a simplicity that increases its potential for development, manufacture and real-world applications in areas ranging from medicine to manufacturing, the scientists say.

In its clasped, or closed, form, the nanomotor measures 2 to 5 nanometers — 2 to 5 billionths of a meter. In its unclasped form, it extends as long as 10 to 12 nanometers. Although the scientists say their calculations show it uses considerably more of the energy in light than traditional solar cells, the amount of force it exerts is proportional to its small size.






Applications in the larger world are more distant. Powering a vehicle, running an assembly line or otherwise replacing traditional electricity or fossil fuels would require untold trillions of nanomotors, all working together in tandem — a difficult challenge by any measure.

“The major difficulty lies ahead,” said Weihong Tan, a UF professor of chemistry and physiology, author of the paper and the leader of the research group reporting the findings. “That is how to collect the molecular level force into a coherent accumulated force that can do real work when the motor absorbs sunlight.”

Tan added that the group has already begun working on the problem.

“Some prototype DNA nanostructures incorporating single photo-switchable motors are in the making which will synchronize molecular motions to accumulate forces,” he said.

To make the nanomotor, the researchers combined a DNA molecule they created in the lab with azobenzene, a chemical compound that responds to light. A high-energy photon prompts one response; lower energy another.

To demonstrate the movement, the researchers attached a fluorophore, or light-emitter, to one end of the nanomotor and a quencher, which can quench the emitting light, to the other end. Their instruments recorded emitted light intensity that corresponded to the motor movement.