Nanotechnology Digest - June 2017

Ceramic nanofibres

Scientists at Brown University, USA, and Tsinghua University, China, have developed a lightweight sponge from tangled nanoscale ceramic fibres. The porous, deformable, heat resistant material could have uses in water purification devices or as an insulating material. The researchers used a method that promises to be inexpensive and scalable to mass manufacture – blow spinning. The process uses air-pressure to blow a solution of the ceramic material through a syringe. As the extruded materials solidify they form into nanofibres which are then heated to remove any solvents leaving behind a tangled mass of ceramic fibres. The sponges showed ability to be compressed by up to 50 percent and then return to their original shape, and were resilient to heat of up to 800° Celsius.

Magnetic nanoparticles for cancer treatment

An international collaboration of scientists has demonstrated the use of spinning magnetic nanoparticles to destroy cancer cells. The team coated nanoparticles with a surface that attaches to proteins expressed predominantly in cancer cells. An in vitro study showed that the coated magnetic nanoparticles were able to enter the cancerous cells. A magnetic field was then applied to the nanoparticles which caused them to form into a chain. Finally, a rotating magnetic field was applied to the chains to cause them to move breaking the host cells’ walls and killing cancer cells with a high effectiveness. According to the scientists, the small size of nanoparticles enables them to reach the site of the cancer cells better than larger microparticles, and the formation of chains allows them to be large enough and hence effective enough when destroying the cells.

Using magnets and nanoparticles to remove oil from water

University of Texas scientists have demonstrated the use of magnets and nanoparticles to remove oil from water – a technology that could have uses in the oil and gas industry, environmental cleanup operations and clean drinking water. Modern oil production methods separate about 95 percent of the oil from produced water but leaves behind small oil droplets. The use of magnetic nanoparticles enables the removal of those remaining particulates. The team used a method called high gradient magnetic separation that is used in mining to remove metals, and in the food industry to remove toxic particles. The team’s advance was designing a coating for the nanoparticle that allows it to bond to oil droplets in the water using electrostatic force – the coating is a polymer that has a positive charge; the oil droplets have a negative charge. After the bonding, the small droplets can be pulled from the water with a magnet. The team plans to develop a treatment system for oil and gas production plants that could handle high volume capacities.

Nanoscale magnification

A British start-up called LIG Nanowise has developed microspheres that promise to increase the magnification strength of optical microscopes fourfold. The company, using microspheres which have a negative refractive index, has created Nanopsis a microsphere microscope attachment that can see in ‘super-resolution’ to 90nm using light. The level of magnification being offered here could potentially allow scientists to see viruses, live and in real time – although this model is still in the development stage the company has released the Nanopsis M for use in materials research. LIG Nanowise are researching the use of microspheres in smartphone displays – to act as sapphire crystal slicers.

Material to protect astronauts from radiation

Scientists at the Australian National University (ANU) have developed a nanomaterial that can reflect or transmit light on demand with temperature control. The material – which can be applied to any surface and is ultrathin the scientists say – could be used to protect astronauts or satellites from ultraviolet or infrared radiation. The technology is said to be significantly better at protecting against harmful radiation than current technologies. The material could be altered to allow its use in the visible light spectrum offering the possibility of light reactive glass in windows among other applications.

Solar powered desalination system

Researchers at Rice University and Yale University have developed a system that combines solar power and nanoparticles to desalinate water – a nanophotonics-enabled solar membrane distillation (NESMD). The system uses a porous membrane with carbon black nanoparticles. The nanoparticles use solar energy to heat water on one side of the membrane. This turns the water into a vapour leaving the salt behind but with the vapour passing through. The scientists say that their system differs from similar systems as it is energy self-sufficient and its efficiency increases with scale.

Dissolving electronics

Scientists at the Vanderbilt University, USA, have developed transient electronics that dissolve at temperatures below 32 degrees Celsius. The electronics – silver nanowires embedded in polymers – were tested in the form of a simple circuit board that controls a LED light which is immersed in a heated bath of warm water. The nanowires are connected in the circuit by the polymers, but if the device’s temperature goes below 32 degrees the polymers dissolve breaking the nanowires’ connections. The technology has potential for use in medical implants. The next step involves integrating semiconductors into the device to make transistors.

Silver nanoparticle infused fibres

Scientists at the Agricultural Research Service's (ARS) Southern Regional Research Center (SRRC) in New Orleans, Louisiana, have developed a method to trap silver nanoparticles inside cotton fibres. Silver nanoparticles are widely used for their anti-microbial properties. The scientists have made fabrics with silver nanoparticles more resistant to the effects of washing by producing the nanoparticles directly in the cotton itself. The process allows for the growing of small nanoparticles of about 12nm in diameter. Tests of the technique showed that after 50 laundering cycles the silver-cotton nanocomposite fibre retained about 93 percent antimicrobial silver nanoparticles. The scientists see fabrics made with this method having potential for use in bandages to help keep a wound or burn clean. The researchers plan to further investigate the efficacy of their material at killing bacteria on a floor surface.

Nanoparticle research for building conservation

The Nanocathedral Project is researching nanomaterials for the conservation of five historic cathedrals across Europe. Nanomaterials such as nanoparticle-based consolidants and polymer nanocomposite coatings will be developed that will provide conservationists with methods to consolidate, protect and control pollutant decomposition, preventing further degradation of the old stonework.

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