Nanotechnology Tech Digest - May 2017

Drug shooting slingshot

A team of researchers from the University of Rome Tor Vergata, Italy, and the University of Montreal, Canada, has created a molecular slingshot made of DNA. The nanoscale slingshot could be used to deliver drugs within the body when triggered by specific disease markers. The molecular slingshot is composed of a synthetic DNA strand – acting as the rubber band mechanism in the slingshot. At either end of the band there are molecular sections (moieties) that can anchor to a natural Y-shaped antibody. When the moieties recognise and bind to the arms of the target antibody the DNA band is stretched and a loaded drug is released. The scientists say that the slingshot can be modified to carry a wide range of drugs and bind with a range of antibodies. They plan to adapt the slingshot to deliver clinically relevant drugs. 

Paper-thin device can act as speaker and microphone 

Scientists at Michigan State University, USA, have created a paper-thin, flexible device that can act as a loudspeaker and microphone. The ultrathin, foldable device is a ferroelectret nanogenerator (FENG) that converts mechanical energy into electrical energy, for example a finger press could be converted into electricity. The device can act as a microphone by picking up sound vibrations and converting them to electrical energy, or a loudspeaker by doing the reverse. The scientists demonstrated the device acting as a microphone for a voice recognition security system, and claimed that it successfully detected only the authorised voice. They also demonstrated the device amplifying a sound signal being fed into the device. The scientists see the device being used as a foldable speaker, noise cancelling sheeting, voice activation and identification device or even as a talking newspaper.

Method to kill mosquitos

Scientists from universities in Italy, India, Saudi Arabia and Taiwan have jointly developed a method to curb the spread of mosquitos and malaria. The team used chitosan or chitin, a substance found in bird beaks, insect eggs and the exoskeletons of animals such as crabs – from which the scientists extracted the chitin they needed. The chitin extract was then mixed with silver nitrate which produced a solution of silver nanoparticles. They then sprayed these over six water reservoirs in India and it was shown to be effective in killing mosquito larvae and pupa. It was also shown that goldfish that ate the nanoparticles containing mosquitos were not harmed.

Spearing worms

Rice University scientist have developed nanoscale probes that can be used to measure electrical signals in cells of living small animals. As the nano-SPEARs (nanoscale suspended electrode arrays) do not harm the animal they would allow for example a worm to be tested repeatedly, enhancing the ability to gather data for disease characterisation and drug interaction. The device acts like a tunnel for worms; the worms get trapped in the tunnel and the nano-SPEARs enter the body to record electrical activity. The nano-SPEARs are created using thin-film deposition and can be made from 200nm to 5 microns thick. The animals suitable for such treatment can be up to several millimetres in size. The lab is using the technology to profile worms with neurodegenerative disease models and to screen for drugs to reduce symptoms. 

Carbon nanobelt synthesised

Scientists at Nagoya University in Japan have synthesised a carbon nanobelt, something that has evaded scientists for the past 70 years. Nanobelts are belt shaped molecules composed of fused benzene rings each consisting of six carbon atoms, and are integral parts of carbon nanotubes widely researched for their electronic and photonic potential. The Nagoya University nanobelt measures 0.83 nm in diameter. It is expected that being able to synthesise nanobelts will give scientists greater control over carbon nanotubes’ diameter and sidewall structure resulting in increased ability to build tubes with desired properties. 

Submarine to deliver drugs into cancer cells & getting into tumours

Researchers at Radboud University in the Netherlands have developed a synthetic nanoscale vesicle that can be loaded with drugs, enter cancer cells and then self-destruct, releasing its load.  The vesicles – a kind of sac naturally produced by the body, that can be filled with liquids or gases – are powered by hydrogen peroxide gas that propels them through the body. They react to chemical triggers when they approach cancer cells, and propel themselves through the cell wall. Inside the cell, triggered by glutathione – a chemical found in high concentrations in cancer cells –  the vesicles disintegrate, releasing their payload. 
An alternative method demonstrated by Washington State University researchers is to deliver the drug to the cancerous cells by attaching it to a white blood cell. This enables the drugs to get past a tumour’s typical wall of blood vessels. In an experiment the scientists implanted a tumour on the flank of a mouse that was then exposed to infrared light to initiate the release of proteins that attract white blood cells. The mouse was then injected with antibody-treated gold nanoparticles that attached themselves to white blood cells. The gold nanoparticles caused the tumour to be heated leading to its death, when also exposed to infrared light. The scientists say that they hope to attach drugs to the nanoparticles in the future. 

Nanoparticles that act like sunscreen

Scientists at the University of San Diego, USA, have developed a sunscreen that uses nanoparticles to mimic the behaviour of melanosomes, melanin producing cells that protect skin from ultraviolet radiation. The synthetic melanin has been tested in skin cell cultures and shown to be an effective mimic of melanosomes in their ability to protect the cells from DNA from UV radiation and to distribute themselves throughout the cells in the tissue sample. The melanin-like nanoparticles were created through the spontaneous oxidation of dopamine. The team sees the technology having uses to help protect sufferers of albinism and vitiligo from cancers caused by UV radiation exposure. 

Nanoscale sensor

Scientists at the University of San Diego have developed a nanoscale optical fibre device that can detect minute forces – 160 femtonewtons – generated by swimming bacteria, and hear the beat of a mouse heart muscle cell – down to -30 decibels. The device – which is ten times more sensitive than the atomic force microscope – consists of a thin fibre of tin dioxide coated in polyethylene glycol, and studded with gold nanoparticles. To use the device the team send a beam of light down the optical fibre which is placed in a solution of cells, and then read the light signals it sends out.  The intensity of the signals indicate how much force or sound the fibre is detecting. Applications envisioned for the sensors include detecting the presence and activity of a single bacterium; monitoring bond formation and breakage; sensing changes to a cell’s mechanical activities that could signal it being attacked; or a mini stethoscope. 

Lego for nanotech

Freidrich-Alexander Universitat (FAU) researchers have built and tested electrical conductors and networks made up of individual synthetic organic semiconductor building-block molecules. This ‘lego-block’ technique is different to conventional lithographic techniques – a material subtraction method that only allows for construction of structures larger than 14 nm – in that it allows scientists to build structures from the bottom up at sizes as small as 1 nm. The researchers can use these blocks to build one dimensional conductors or two-dimensional networks in controlled environments, producing regular, structurally perfect nanoelectronic components with determined properties. 

 

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