Carbon nanotube fibers make superior links to brain

Carbon nanotube fibers invented at Rice University may provide the best way to communicate directly with the brain. The fibers have proven superior to metal electrodes for deep brain stimulation and to read signals from a neuronal network. Because they provide a two-way connection, they show promise for treating patients with neurological disorders while monitoring the real-time response of neural circuits in areas that control movement, mood and bodily functions. carbon nanotube fibers Pairs of carbon nanotube fibers have been tested for potential use as implantable electrodes to treat patients with neurological disorders like Parkinson's disease. The fibers invented at Rice University proved to be far better than metallic wires now used to stimulate neurons in the brain. (Courtesy of the Pasquali Lab) New experiments at Rice demonstrated the biocompatible fibers are ideal candidates for small, safe electrodes that interact with the brain’s neuronal system, according to the researchers. They could replace much larger electrodes currently used in devices for deep brain stimulation therapies in Parkinson’s disease patients. They may also advance technologies to restore sensory or motor functions and brain-machine interfaces as well as deep brain stimulation therapies for other neurological disorders, including dystonia and depression, the researchers wrote. The paper appeared online this week in the American Chemical Society journal ("Neural Stimulation and Recording with Bidirectional, Soft Carbon Nanotube Fiber Microelectrodes"). The fibers created by the Rice lab of chemist and chemical engineer Matteo Pasquali consist of bundles of long nanotubes originally intended for aerospace applications where strength, weight and conductivity are paramount. The individual nanotubes measure only a few nanometers across, but when millions are bundled in a process called wet spinning, they become thread-like fibers about a quarter the width of a human hair. “We developed these fibers as high-strength, high-conductivity materials,” Pasquali said. “Yet, once we had them in our hand, we realized that they had an unexpected property: They are really soft, much like a thread of silk. Their unique combination of strength, conductivity and softness makes them ideal for interfacing with the electrical function of the human body.” The simultaneous arrival in 2012 of Caleb Kemere, a Rice assistant professor who brought expertise in animal models of Parkinson’s disease, and lead author Flavia Vitale, a research scientist in Pasquali’s lab with degrees in chemical and biomedical engineering, prompted the investigation. “The brain is basically the consistency of pudding and doesn’t interact well with stiff metal electrodes,” Kemere said. “The dream is to have electrodes with the same consistency, and that’s why we’re really excited about these flexible carbon nanotube fibers and their long-term biocompatibility.” Flavia Vitale, a postdoctoral researcher at Rice, prepares carbon nanotube fibers for testing. Vitale is lead author of a new study that determined the thread-like fibers made of millions of carbon nanotubes may be suitable as electrodes to stimulate the brains of patients with neurological diseases. Photo by Jeff Fitlow Weeks-long tests on cells and then in rats with Parkinson’s symptoms proved the fibers are stable and as efficient as commercial platinum electrodes at only a fraction of the size. The soft fibers caused little inflammation, which helped maintain strong electrical connections to neurons by preventing the body’s defenses from scarring and encapsulating the site of the injury. The highly conductive carbon nanotube fibers also show much more favorable impedance – the quality of the electrical connection — than state-of-the-art metal electrodes, making for better contact at lower voltages over long periods, Kemere said. The working end of the fiber is the exposed tip, which is about the width of a neuron. The rest is encased with a three-micron layer of a flexible, biocompatible polymer with excellent insulating properties. The challenge is in placing the tips. “That’s really just a matter of having a brain atlas, and during the experiment adjusting the electrodes very delicately and putting them into the right place,” said Kemere, whose lab studies ways to connect signal-processing systems and the brain’s memory and cognitive centers. Doctors who implant deep brain stimulation devices start with a recording probe able to “listen” to neurons that emit characteristic signals depending on their functions, Kemere said. Once a surgeon finds the right spot, the probe is removed and the stimulating electrode gently inserted. Rice carbon nanotube fibers that send and receive signals would simplify implantation, Vitale said. Caleb Kemere shows a brain atlas as he discusses new research aimed at using carbon nanotube fibers invented at Rice as electrodes for deep brain stimulation of patients with neurological disorders like Parkinson's disease. The flexible fibers are much smaller than the metallic electrodes they would replace and far more effective in stimulating and recording signals from neurons. Photo by Jeff Fitlow The fibers could lead to self-regulating therapeutic devices for Parkinson’s and other patients. Current devices include an implant that sends electrical signals to the brain to calm the tremors that afflict Parkinson’s patients. “But our technology enables the ability to record while stimulating,” Vitale said. “Current electrodes can only stimulate tissue. They’re too big to detect any spiking activity, so basically the clinical devices send continuous pulses regardless of the response of the brain.” Kemere foresees a closed-loop system that can read neuronal signals and adapt stimulation therapy in real time. He anticipates building a device with many electrodes that can be addressed individually to gain fine control over stimulation and monitoring from a small, implantable device. “Interestingly, conductivity is not the most important electrical property of the nanotube fibers,” Pasquali said. “These fibers are intrinsically porous and extremely stable, which are both great advantages over metal electrodes for sensing electrochemical signals and maintaining performance over long periods of time.”
read more "Carbon nanotube fibers make superior links to brain"

EPA proposes reporting and record keeping requirements on nanomaterials

The U.S. Environmental Protection Agency (EPA) is proposing one-time reporting and recordkeeping requirements on nanoscale chemical substances in the marketplace. “Nanotechnology holds great promise for improving products, from TVs and vehicles to batteries and solar panels, said Jim Jones, EPA’s Assistant Administrator for Chemical Safety and Pollution Prevention. “We want to continue to facilitate the trend toward this important technology. Today’s action will ensure that EPA also has information on nano-sized versions of chemicals that are already in the marketplace.” EPA currently reviews new chemical substances manufactured or processed as nanomaterials prior to introduction into the marketplace to ensure that they are safe. For the first time, the agency is proposing to use TSCA to collect existing exposure and health and safety information on chemicals currently in the marketplace when manufactured or processed as nanoscale materials. The proposal will require one-time reporting from companies that manufacture or process chemical substances as nanoscale materials. The companies will notify EPA of:

  • certain information, including specific chemical identity;

  • production volume;

  • methods of manufacture; processing, use, exposure, and release information; and,

  • available health and safety data.


Nanoscale materials have special properties related to their small size such as greater strength and lighter weight, however, they may take on different properties than their conventionally-sized counterpart. The proposal is not intended to conclude that nanoscale materials will cause harm to human health or the environment; Rather, EPA would use the information gathered to determine if any further action under the Toxic Substances Control Act (TSCA), including additional information collection, is needed. The proposed reporting requirements are being issued under the authority of section 8(a) under TSCA. The agency is requesting public comment on the proposed reporting and recordkeeping requirements 90 days from publication in the Federal Register. EPA also anticipates holding a public meeting during the comment period. The time and place of the meeting will be announced on EPA’s web page at (add link) Additional information and a fact sheet on the specifics of the proposed rule and what constitutes a nanocale chemical material can be found at http://1.usa.gov/19lclav.
read more "EPA proposes reporting and record keeping requirements on nanomaterials"

Nanorobotic agents open the blood-brain barrier, offering hope for new brain treatments

Magnetic nanoparticles can open the blood-brain barrier and deliver molecules directly to the brain, say researchers from the University of Montreal, Polytechnique Montréal, and CHU Sainte-Justine ("Remote control of the permeability of the blood–brain barrier by magnetic heating of nanoparticles: A proof of concept for brain drug delivery"). This barrier runs inside almost all vessels in the brain and protects it from elements circulating in the blood that may be toxic to the brain. The research is important as currently 98% of therapeutic molecules are also unable to cross the blood-brain barrier. “The barrier is temporary opened at a desired location for approximately 2 hours by a small elevation of the temperature generated by the nanoparticles when exposed to a radio-frequency field,” explained first author and co-inventor Seyed Nasrollah Tabatabaei. “Our tests revealed that this technique is not associated with any inflammation of the brain. This new result could lead to a breakthrough in the way nanoparticles are used in the treatment and diagnosis of brain diseases,” explained the co-investigator, Hélène Girouard. “At the present time, surgery is the only way to treat patients with brain disorders. Moreover, while surgeons are able to operate to remove certain kinds of tumors, some disorders are located in the brain stem, amongst nerves, making surgery impossible,” added collaborator and senior author Anne-Sophie Carret. Although the technology was developed using murine models and has not yet been tested in humans, the researchers are confident that future research will enable its use in people. “Building on earlier findings and drawing on the global effort of an interdisciplinary team of researchers, this technology proposes a modern version of the vision described almost 40 years ago in the movie Fantastic Voyage, where a miniature submarine navigated in the vascular network to reach a specific region of the brain,” said principal investigator Sylvain Martel. In earlier research, Martel and his team had managed to manipulate the movement of nanoparticles through the body using the magnetic forces generated by magnetic resonance imaging (MRI) machines. To open the blood-brain barrier, the magnetic nanoparticles are sent to the surface of the blood-brain barrier at a desired location in the brain. Although it was not the technique used in this study, the placement could be achieved by using the MRI technology described above. Then, the researchers generated a radio-frequency field. The nanoparticles reacted to the radio-frequency field by dissipating heat thereby creating a mechanical stress on the barrier. This allows a temporary and localized opening of the barrier for diffusion of therapeutics into the brain. The technique is unique in many ways. “The result is quite significant since we showed in previous experiments that the same nanoparticles can also be used to navigate therapeutic agents in the vascular network using a clinical MRI scanner,” Martel remarked. “Linking the navigation capability with these new results would allow therapeutics to be delivered directly to a specific site of the brain, potentially improving significantly the efficacy of the treatment while avoiding systemic circulation of toxic agents that affect healthy tissues and organs,” Carret added. “While other techniques have been developed for delivering drugs to the blood-brain barrier, they either open it too wide, exposing the brain to great risks, or they are not precise enough, leading to scattering of the drugs and possible unwanted side effect,” Martel said. Although there are many hurdles to overcome before the technology can be used to treat humans, the research team is optimistic. “Although our current results are only proof of concept, we are on the way to achieving our goal of developing a local drug delivery mechanism that will be able to treat oncologic, psychiatric, neurological and neurodegenerative disorders, amongst others,” Carret concluded.
read more "Nanorobotic agents open the blood-brain barrier, offering hope for new brain treatments"