Nanotechnology

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Nanotech-laser kills cancer, preserves healthy cells

BY MARK SHWARTZ

Scientists at Stanford University have developed a new laser therapy that destroys cancer cells but leaves healthy ones unharmed. The new, non-invasive treatment is described in a study published in the Aug. 1 online edition of the Proceedings of the National Academy of Sciences (PNAS).

"One of the longstanding problems in medicine is how to cure cancer without harming normal body tissue," says Hongjie Dai, an associate professor of chemistry at Stanford and co-author of the study. "Standard chemotherapy destroys cancer cells and normal cells alike. That's why patients often lose their hair and suffer numerous other side effects. For us, the Holy Grail would be finding a way to selectively kill cancer cells and not damage healthy ones."
Nanotechnology

For the PNAS experiment, Dai and his colleagues used a basic tool of nanotechnology—carbon nanotubes, synthetic rods that are only half the width of a DNA molecule. Thousands of nanotubes could easily fit inside a typical cell.

"An interesting property of carbon nanotubes is that they absorb near-infrared light waves, which are slightly longer than visible rays of light and pass harmlessly through our cells," Dai says. But shine a beam of near-infrared light on a carbon nanotube, and the results are dramatic. Electrons in the nanotube become excited and begin releasing excess energy in the form of heat.

In the experiment, Stanford researchers found that if they placed a solution of carbon nanotubes under a near-infrared laser beam, the solution would heat up to about 158 degrees F (70 C) in two minutes. When nanotubes were placed inside cells and radiated by the laser beam, the cells were quickly destroyed by the heat. However, cells without nanotubes showed no effects when placed under near-infrared light.

"It's actually quite simple and amazing," Dai observes. "We're using an intrinsic property of nanotubes to develop a weapon that kills cancer."
Trojan horse

To assure that only diseased cells were destroyed in the experiment, the scientists had to find a way to selectively deliver carbon nanotubes into cancer cells and not into healthy ones. Dai and his co-workers achieved this by performing a bit of biochemical trickery. Unlike normal cells, the surface of a cancer cell contains numerous receptors for a vitamin known as folate. The researchers decided to coat the nanotubes with folate molecules, which would only be attracted to diseased cells with folate receptors.

The experiment worked as predicted. Most of the folate-coated nanotubes ended up inside cancer cells, bypassing the normal cells—like Trojan horses crossing the enemy line. Once the nanotubes were planted inside, the researchers shined the near-infrared laser on the cancer cells, which soon heated up and died.

"Folate is just an experimental model that we used," Dai says. "In reality, there are more interesting ways we can do this. For example, we can attach an antibody to a carbon nanotube to target a particular kind of cancer cell."

One example is lymphoma, or cancer of the lymphatic system. Like many cancers, lymphoma cells have well-defined surface receptors that recognize unique antibodies. When attached to a carbon nanotube, the antibody would play the role of a Trojan horse. Dai and Dean Felsher, a lymphoma researcher in the Stanford School of Medicine, have begun a collaboration using laboratory mice with lymphoma. The researchers want to determine if shining near-infrared light on the animal's skin will destroy lymphatic tumors, while leaving normal cells intact.

"It's a really interesting idea," says Felsher, an assistant professor of medicine and of pathology. "For a long time people have thought about ways to target cancer cells, and this is a very promising technique."

Researchers at Rice University recently conducted a similar experiment on mice with cancerous tumors. Instead of carbon nanotubes, the Rice team injected the tumors with gold-coated nanoshells and exposed the animals to near-infrared light for several minutes. The tumors disappeared within 10 days without damaging any healthy tissue.
Future applications

Dai points out that the carbon nanotubes also can be delivered to diseased cells by direct injection. "In breast cancer, for example, there might come a time when we inject nanotubes into the tumor and expose the breast to near-infrared light," he says. This benign therapy could potentially eliminate months of debilitating chemotherapy and radiation treatment, he adds.

"The laser we used is a 3-centimeter beam that's held like a flashlight," he notes. "We can take the beam and put anywhere we want. We can shine it on a local area of the skin or inside an internal organ using a fiber-optic device."

Dai has applied for a patent on the procedure through Stanford's Office of Technology Licensing (OTL). He also has patented another technique that's designed to deliver molecules of DNA, RNA or protein directly into the cell nucleus to fight various infections and diseases. That method uses pulses of near-infrared light to shake the therapeutic molecule loose from the nanotube after they have entered the cell.

"Nanotechnology has long been known for its applications in electronics," Dai concludes. "But this experiment is a wonderful example of nanobiotechnology—using the unique properties of nanomaterials to advance biology and medicine."

Dai's graduate student, Nadine Wong Shi Kam, is lead author of the PNAS study. Other co-authors are Michael O'Connell, a former postdoctoral fellow in the Department of Chemistry, and graduate student Jeffrey A. Wisdom in the Department of Applied Physics.

The study was partly supported by the National Science Foundation Center on Polymer Interfaces and Macromolecular Assemblies, a research partnership among Stanford, IBM Almaden Research Center, University of California-Davis and University of California-Berkeley..

The Next Line of Antibiotic Defense May Be Nano-Particles
In the near future, a visit to the doctor's office may not involve a z-pack worth of antibiotics to fight an infection, but may instead involve a simple shot in the arm of nanoparticles. From there, the particles will attack infections, killing off the bad cultures and leaving the good ones behind.

And here's the thing: it's already sort of here. New research by the University of Colorado-Boulder showed that, in initial trials, the nanoparticles were able to decimate 92 percent of drug-resistant bacteria. Built out of similar materials as semiconductors, they're nearly invisible to the naked eye. When exposed to light, they activate. By modifying the frequency of the light, it can send the swarm of nanobots to attack particular cells.
The latter is why previous efforts have often failed: they attacked healthy cells alongside bacterial infections. But that wasn't an issue during these tests. The nanoparticles left healthy cells alone, going after specific strains like E. Coli when activated by the right light.

The researchers also believe that, even if the bacteria adapt to the nanoparticle swarm attacks, they'll be able to make slight modifications in order to go after the mutated bacterial infections as well. This could be a way to combat bacterial infections most effectively in a potential post-antibiotic age.

The research was published in Nature Materials.

Light-driven bioelectronic implants without batteries
(Nanowerk Spotlight) Benefitting from the miniaturization enabled by nanotechnologies, bioelectronics is a growing research field that is concerned with the convergence of biology and electronics: the application of biological materials and processes in electronics; and the use of electronic devices in living systems.Among the latter, implantable bioelectronic devices wirelessly powered by different stimuli provide electrical impulses to precisely modulate the body's neural circuits – although wireless powering and remote manipulation still remain a major challenge for the practical use of these devices, which include retinal and cochlear implants; deep brain stimulators for epilepsy and Parkinson's disease; pacemakers; and brain-machine interfaces.Adding to the options for wirelessly powering implants from outside the body, researchers in China are proposing a light-driven powering device using near infrared rays (nIR). Flashing light impulses, which are absorbed by the device, induce temperature fluctuation, thus generating voltage/current pulses which can be used for charging a battery or biological stimulations."Compared to the wireless power transport by electromagnetic coupling, near-infrared light with a wavelength of 760-1500 nm – known for its heating and medical physical therapy effects – provides an alternative wireless power that can pe*****te into human tissue up to a depth of 4-10 cm," Prof. Hongzhong Liu and Dr. Weitao Jiang, from the State Key Laboratory for Manufacturing Systems Engineering at Xi'an Jiaotong University, explain to Nanowerk.The team reported their findings in the October 29, 2015 online edition of Advanced Functional Materials ("Flexible battery-less bioelectronic implants: wireless powering and manipulation by near infrared light").Inspired by the photothermal effect of nIR in biomedical applications, Liu's team fabricated a remotely/wirelessly controlled battery-less implantable device driven by nIR.Flexible Battery-Less Bioelectronic Implanta) Modulation of voltage pulse for graphene/PVDF/graphene by irradiation time when the non-irradiation time is fixed. b) Laminated cell number dependence of the open-circuit voltage output and the temperature on the top. c) Scheme of a compact, flexible battery-less device for wireless powering and nerve stimulators which can be remotely manipulated by nIR irradiation and Photograph of laminated sample (top left corner). (Image: State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University) (click on image to enlarge)"What has motivated us to add to the existing devices for wireless powering systems is that a miniature power supply without the need for a battery is greatly desired for bioelectronics," says Jiang. "Besides, for bioelectronic intervention in body, device flexibility and the controllability of stimuli are also the greatest challenges.""Our flexible and compact device can generate electrical pulses with controllable amplitude and width when remotely irradiated by nIR," notes Liu. "Not only can it supply power to implantable bioelectronics, but it also provides adjustable electrical pulses for nerve stimulation.""In nerve stimulation, it is important to modulate the impulses that flow through the stimulated nerves," he elaborates. "The stimulus waveforms –i.e., amplitude; pulse width; monophasic versus biphasic; and the delay between the two phases of the biphasic pulse – provide the greatest excitability differences for different nerve fibers."The scientists point out that, in contrast to wireless powering systems driven by electromagnetic coupling, nIR-driven systems can not only realize far-field energy transfer but also be fabricated as a metal-free system; which is a great advantage in in vivo applications.This wireless powering system combines PVDF – a specialty polymer in the fluoropolymer family – as active pyroelectric material with graphene as the electrode material."PVDF exhibits lightweight, mechanical flexibility and biocompatibility, which are particularly interesting attributes for wearable or implantable devices," says Jiang. "In addition, the strong infrared absorption of PVDF makes it highly suitable for nIR-driven wireless powering system."Due to its excellent electrical and thermal conductivity, high surface area, and high flexibility, graphene has attracted much attention in recent years. While graphene possesses low absorption inherently in the infrared, it exhibits a transparency of 97.7% in visible wavelengths and even higher transparency in the infrared.Each cell in the team's implantable power device is composed of a laminated graphene-PVDF-graphene sandwich, combining the high transparency of graphene and the strong infrared absorption of PVDF thin-film. This serves to enhance its electric properties while reducing the device temperature to avoid damage to intervening and surrounding normal tissue.To demonstrate the practical use of their device, the researchers implanted their power generation device as a stimulator for real-time functional electrical stimulation of a sciatic nerve of a frog and a rat heart, by a remote control by nIR irradiation.Apart from pacemakers and nerve stimulation, direct electrical activation has been widely used to recover the function of neurons. Going forward, the team will explore their device's application in the area of neural recovery by remote control in vitro and integrate some functional devices, i.e., compact camera, and stimuli tips, on the developed internal stimuli systems.By Michael Berger. Copyright © Nanowerk

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New solar power
nanotechnology material
converts 90 percent of
captured light into heat
( Nanowerk News ) A multidisciplinary
engineering team at the University of
California, San Diego developed a new
nanoparticle-based material for
concentrating solar power plants
designed to absorb and convert to
heat more than 90 percent of the
sunlight it captures. The new material
can also withstand temperatures
greater than 700 degrees Celsius and
survive many years outdoors in spite
of exposure to air and humidity. Their
work, funded by the U.S. Department
of Energy's SunShot program, was
published recently in two separate
articles in the journal Nano Energy
( "Tandem structured spectrally
selective coating layer of copper
oxide nanowires combined with cobalt
oxide nanoparticles" ).
By contrast, current solar absorber
material functions at lower
temperatures and needs to be
overhauled almost every year for high
temperature operations.
Engineers at UC San Diego have
developed a nanoparticle-based
material for concentrating solar power
plants that converts 90% of captured
sunlight to heat. With particle sizes
ranging from 10 nanometers to 10
micrometers, the multiscale structure
traps and absorbs light more efficiently
and at temperatures greater than 700
degrees Celsius. (Image: Renkun Chen,
mechanical engineering professor, UC
San Diego Jacobs School of
Engineering)
"We wanted to create a material that
absorbs sunlight that doesn't let any
of it escape. We want the black hole
of sunlight," said Sungho Jin, a
professor in the department of
Mechanical and Aerospace
Engineering at UC San Diego Jacobs
School of Engineering. Jin, along with
professor Zhaowei Liu of the
department of Electrical and
Computer Engineering, and
Mechanical Engineering professor
Renkun Chen, developed the Silicon
boride-coated nanoshell material.
They are all experts in functional
materials engineering.
The novel material features a
"multiscale" surface created by using
particles of many sizes ranging from
10 nanometers to 10 micrometers.
The multiscale structures can trap
and absorb light which contributes to
the material's high efficiency when
operated at higher temperatures.
Concentrating solar power (CSP) is
an emerging alternative clean energy
market that produces approximately
3.5 gigawatts worth of power at
power plants around the globe—
enough to power more than 2 million
homes, with additional construction in
progress to provide as much as 20
gigawatts of power in coming years.
One of the technology's attractions is
that it can be used to retrofit existing
power plants that use coal or fossil
fuels because it uses the same
process to generate electricity from
steam.
Traditional power plants burn coal or
fossil fuels to create heat that
evaporates water into steam. The
steam turns a giant turbine that
generates electricity from spinning
magnets and conductor wire coils.
CSP power plants create the steam
needed to turn the turbine by using
sunlight to heat molten salt. The
molten salt can also be stored in
thermal storage tanks overnight
where it can continue to generate
steam and electricity, 24 hours a day
if desired, a significant advantage
over photovoltaic systems that stop
producing energy with the sunset.
UC San Diego mechanical engineering
professor Renkun Chen spray paints a
novel material designed that could
significantly improve the cost
competitiveness of solar energy by
converting more than 90 percent of the
sunlight it captures into heat. Funded
by the US Department of Energy's
SunShot Initiative, the team is tasked
with coming up with a material that can
last for years in the air and humidity
before it needs to be repainted, a feat
the team believes it is close to
achieving. (Image: David Baillot/UC San
Diego Jacobs School of Engineering)
One of the most common types of
CSP systems uses more than 100,000
reflective mirrors to aim sunlight at a
tower that has been spray painted
with a light absorbing black paint
material. The material is designed to
maximize sun light absorption and
minimize the loss of light that would
naturally emit from the surface in the
form of infrared radiation.
The UC San Diego team's combined
expertise was used to develop,
optimize and characterize a new
material for this type of system over
the past three years. Researchers
included a group of UC San Diego
graduate students in materials
science and engineering, Justin
Taekyoung Kim, Bryan VanSaders,
and Jaeyun Moon, who recently
joined the faculty of the University of
Nevada, Las Vegas. The synthesized
nanoshell material is spray-painted in
Chen's lab onto a metal substrate for
thermal and mechanical testing. The
material's ability to absorb sunlight is
measured in Liu's optics laboratory
using a unique set of instruments that
takes spectral measurements from
visible light to infrared.
Current CSP plants are shut down
about once a year to chip off the
degraded sunlight absorbing material
and reapply a new coating, which
means no power generation while a
replacement coating is applied and
cured. That is why DOE's SunShot
program challenged and supported UC
San Diego research teams to come
up with a material with a substantially
longer life cycle, in addition to the
higher operating temperature for
enhanced energy conversion
efficiency. The UC San Diego
research team is aiming for many
years of usage life, a feat they
believe they are close to achieving.
Modeled after President Kennedy's
moon landing program that inspired
widespread interest in science and
space exploration, then-Energy
Secretary Steven P. Chu launched the
Sunshot Initiative in 2010 with the
goal of making solar power cost
competitive with other means of
producing electricity by 2020.
Source: University of California - San
Diego