Nanotech Digest - April 2017

Pressure fabrication of nanowire arrays

A team from Sandia National Laboratories has developed a fabrication method for nanowire array structures like those found under the surface of touchscreens. The material is created in a process called stress-induced fabrication which is currently used to, for example, emboss credit cards. The method is purported to be 9 million times faster than chemical methods. The team used Sandia’s Veloce pulsed power machine that can generate 100,000 atmospheres of pressure. The method produces no chemical waste, nor any material waste (as only the required amount is placed on the substrate). 

Mercury removing sponge

Scientists at the University of Minnesota have developed a sponge that can remove mercury from contaminated water within seconds. The sponge is made by growing selenium nanomaterials on the surface and interior of a kitchen sponge. According to the university’s report, it can absorb mercury from taps, lakes, and industrial wastewater to below detectable limits in less than five seconds (or five minutes for industrial wastewater). The nanomaterials adsorb the mercury and convert it into non-toxic compounds, and the sponge can then be disposed of in landfill. The team currently has three patents on the technology. 

Nanowire electrodes

Scientists led by the University of California San Diego have developed nanowires that can record electrical activity of neurons in fine detail making it potentially useful in researching drugs to treat neurodegenerative diseases. The scientists created a high-density array of nanowires integrated onto a circuit. They then used these to record electrophysiological recordings from rat and mice neurons for a period of eight to 14 days.  

More stable perovskite cells 

Researchers from Aalto University and Uppsala University, Finland, and École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have discovered a way to make perovskite cells stable for longer periods of time using random network nanotube films composed of single walled carbon nanotubes that under microscopes looks like spaghetti on a plate. To achieve improved stability the team replaced the conventional layer of gold used in perovskite solar cells with the carbon nanotube film. 

Nanotube textiles

University of Illinois researchers have created carbon nanotube textiles that have high electrical conductivity and a toughness that is 50 times higher than the copper film currently used in electronics. The carbon nanotubes were synthesised by chemical vapour deposition to form parallel lines of 5 and 10 nanometre length and 20-60 nanometre height. The team used self-driven capillary force to staple the nanotubes together. The aligned carbon nanotubes would be suitable for Micro-Electro-Mechanical Systems (MEMS), supercapacitor electrodes, electrical cables, artificial muscles, and multi-functional composites.

Pressure sensor

Scientists at UNIST (Ulsan National Institute of Science and Technology) in South Korea have created a three-dimensional tactile and pressure sensor. It has graphene field-effect transistors (FETs) between air-dielectric layers. The scientists said that using air as dielectric layers in FETs improves the transistor performance because of the clean interface between the graphene channel and the air. Displacement of air when pressure is applied to the sensor causes an electrical signal to be transported through metal nanowires and the graphene channel. The location and intensity of the pressure can be detected by the device. It can measure low applied pressure such as tapping to high pressure such as human body weight. The scientists see the possible future application of this material in touchscreens or wearables such as pressure sensitive shoes. 

Nanoparticle nasal spray

Engineers from Washington University in St Louis have developed a nanoparticle nasal spray that could improve the speed at which drugs reach the brain. They developed an aerosol of gold nanoparticles of controlled size, shape and surface charge. They then applied the aerosol to a locust’s antennae and observed that the gold nanoparticles travelled through the olfactory nerves. Because of the diminutive size of the particles they are able to easily pass through the blood-brain barrier. In the locust the particles had entered the brain within a couple of minutes. The team will continue experimenting by fusing the gold particles with various medicines. 

Medicine and nanotech

Below are three stories about nanotechnology’s promise as a tool to help in medical treatment.
A team of researchers from Mayo Clinic, an American health care provider, has developed a type of nanoparticle that can fight cancer. In a study involving mice those injected with the patented nanoparticle – Multivalent Bi-specific Nano-Bioconjugate Engager – showed a reduction in tumour size of 70-80%. The treated mice also showed resistance when exposed to cancer cells a month after the treatment. It is believed that this is because the treatment activates the entire immune system to attack the tumour which prompts the body to create a memory system that minimizes tumour recurrence. 
Researchers at Fred Hutchinson Cancer Research Center have developed a biodegradable nanoparticle that can be used to genetically program immune cells to recognize and destroy cancer cells in vivo.  The research carried out on mice showed a significant slowdown or elimination of leukaemia with application of the nanoparticle-programmed immune cells (T-cells). Currently genetic manipulation of T-cells is a time-consuming process, involving taking the cells from the patient and altering them before replacing them. The team is now trying to prove the safety of his system for human patients. 
A team of French researchers from multiple institutions have developed a nanoparticle based Prussian blue that could help eliminate radioactive contamination in the human body. Caesium is a radioactive particle that can be absorbed by the human body and its approved treatment is Prussian blue pigment (also known by the trade name Radiogardase and iron hexacyanoferrate). The French team’s nanoparticle-based pigment is claimed to be more efficient at removing caesium from the body than Radiogardase, requiring lower dosage levels. 

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