Top 10 things nanotechnology has made smaller and better

I've talked about nanotechnology before. Here, I'll talk about different products and technologies that are currently using nanoparticles or nanomaterials, and that have been improved by this area of science.

10- Fuel additives

Fuel price is the most important reason why fuel efficiency needs to be improved. Fuel additives goes in place number 10, because new green energy sources are being researched at the moment using nanomaterials, which is much better for the environment in the long run and will be much cheaper. 

At the moment, it has been shown that adding cerium oxide nanoparticles to fuel reduces the amount of fuel used, it also helps decomposition of unburnt hydrocarbons and soot, and reduces the amount of pollutants emitted in the exhaust. This technology is currently used in the UK, for buses.

One disadvantage to the use of nanoparticles in this matter is the emission of particles to the environment. These particles are likely to accumulate in the environment, in particular in roadside areas, which will result in pollution.

9 –  Construction

Nanomaterials can be very interesting to the construction industry, the provide very durable, long-lived and lightweight construction materials. Very good novel insulation nano-materials are already available on the market, and they seem to improve energy efficiency. Surface coatings are also available and being used currently, these coatings promise to conserve resources, for example water, energy and cleaning agents. Because of their high prices, the reality is that nano- products are still not very widely used in the conservative construction industry, which for the time being prefers to rely on proven, conventional products.

They are mostly used in four sectors, cement-bound construction materials, noise reduction and thermal insulation or temperature regulation, surface coatings to improve the functionality of various materials, and fire protection.

8- Cosmetics – from sunscreen to anti-aging cream

One very important use of nanomaterials in cosmetics is sunscreens. Titanium dioxide and zinc dioxide nanoparticles are currently being used in sunscreens (especially in Australia) to block UVA and UVB light very efficiently, as well as to make sunscreens less oily and spread better on the skin without leaving residues.  

Another important use is to deliver active ingredients in anti-aging screens more easily. Vitamin C, for example, is an antioxidant used to fight skin damage due to age, which works best below the top layer of skin. In bulk form, vitamin C is not very stable and is difficult to penetrate the skin, and the nano form will improve this. Nano emulsions, which means mixing two unblendable liquids – like vinegar and oil, are being used as anti-aging sprays to transport beneficial compounds deep into the skin and in high concentrations. Nano gold is used in one moisturiser available in the UK, they allege that it has healing and anti-oxidant properties.

7- Wound treatment/ antibacterial activity

It is well known that silver has antibacterial properties and is used for wound healing and burn treatment. Reducing the size of materials by using nanoparticles increases the efficiency and improves their properties. So, incorporating silver nanoparticles into the wound bandages will improve their healing properties. 

Because of these antibacterial properties, silver nanoparticles are also being used in many products, like refrigerators, washing machines, air conditioning, toys, pacifiers, clothing, food storage, etc.

6- Sports

Because of their strength and lightweight, nanoparticles are being added to sporting goods. Nanomaterials are being used in tennis rackets, which contain carbon nanotubes to make them extremely strong as well as light, also in golf clubs and shoes. Some shin-pads for footballers are made with nano-structured plastics. Floyd Landis won the Tour de France on a bicycle which had a nano-based plastic frame, and now mountain bikes with these frames are available in the market. Footballs and tennis balls are being improved by using nano-clays, which are barrier materials and retain pressure.

Clothing and fabrics are also being enhanced by nanomaterials, from antibacterial socks, using silver nanoparticles, to waterproof jackets (and sails for boats) and wind resistant clothing that is breathable – for higher temperatures.

5- Sensors and electronics

One thing that nanotechnology has been making better is transparent electronics. Highly flexible and transparent electronic devices will rely on essentially invisible electronic and optoelectronic circuits.  Nanopaper has started to replace plastic substrates because is lightweight and also low-cost and versatile.This nanopaper, made from cellulose like normal paper, has a surface that is less rough and has a much higher transparency than traditional paper. Nanopaper transistors have been made, by Liangbing Hu, an Assistant Professor in the Department of Materials Science and Engineering at the University of Maryland.

Silicon nanomembranes are also being researched to make systems that match the mechanics of the epidermis, and take the full three dimensional shapes of the fingertip as well as other appendages or even internal organs, like the heart. This technology is known as fingertip electronics.

Top: Turning the tube inside out relocates the array on the inner surface of the finger-tube, shown here at the midway point of this flipping process. Bottom: Multiplexed array of electrotactile stimulators in a stretchable, mesh geometry on the inner surface of an elastomeric finger-tube. (Images: Rogers Group, University of Illinois at Urbana-Champaign)

Quantum dots and silicon are being used to make LEDS, and a wide range of products, including lamps, displays and photovoltaics.

4- Environmental clean up

Clean water is a big concern in many countries in the world, where water sources are scarce and contaminated. Nanotechnology has proven already to be an inexpensive and efficient source of water treatment.

It has been found that magnetic rust nanoparticles bind to arsenic; the rust and arsenic can then be lifted out of the water by using only a handheld magnet. Also, iron based nano-filters have been developed as a low cost alternative to carbon-based filters. Iron filters can remove large volumes or chlorine and mercury, amongst other contaminants.

3- Technology – microchips

Some of you might not remember bulky and heavy cell phones and big and slow computers, but some of us do. Nanotechnology has been the key in making machines smaller with a larger memory. Silicon-based chips have improved speed and capacity of different devices for the last five decades.  The switches are becoming smaller and smaller, achieving dimensions with widths of just a few atoms.

Home computer in the 50's

First cellphone

Cellphone evolution

 Currently, I.B.M. physicists and chemists are working with carbon nanotubes, which are single sheets of carbon rolled into tubes, to improve conductivity and reduce size even further. A paper was published in October 2012 in the journal Nature Nanotechnology, where the researchers created patterned arrays of nanotubes on a surface, they would stick nanotubes in some areas and left other areas untouched.

2- Clean energy

To avoid further contamination and reduce energy prizes it is very important to find new and clean sources of energy. Nanotechnology has been a big part of finding more efficient and smaller new energy sources. With very small nanoparticles we can harvest very large amounts of energy.

In 2013 Nano Letters published "Toward Large-Scale Energy Harvesting by a Nanoparticle-Enhanced Triboelectric Nanogenerator", the researchers found a mechanical energy-harvesting technique – a triboelectric nanogenerator – which effectively converts ambient mechanical energy into electrical energy.

Above, the schematic and (b) photograph of a fabricated triboelectric nanogenerator. (c) SEM image of gold nanoparticles coated on gold surface. (d) Process flow for fabricating the nanogenerator. (Reprinted with permission from American Chemical Society)

Solar cells are also an important source of clean energy, many researchers are investigating the development of flexible solar cells to improve efficiency and lower manufacturing costs. The biggest problem is that inorganic solar cells have an efficiency of more than 10%, while flexible polymer solar cells still show a low efficiency (6 – 7%), this needs to be improved. A review paper in ACS NANO ("Nanoimprinted Polymer Solar Cell") talks about imprinted solar cells, which is a method that could improve the efficiency of both organic and inorganic solar cells.

Graphene has also shown great potential in the area of solar cells, which would be inexpensive, lightweight and flexible. Graphene would also improve supercapacitors, lithium-ion batteries, and catalysis for fuel cells.

1.- Medicine  - drug delivery

This has been an area in which nanotechnology has been very important since the beginning. It is clear that most of the active ingredient of drugs is lost in the process of the delivery, through pills, injection, etc., with nanotechnology there has been a constant search to improve the targeting of organs and improve efficiency.

In March 2013 Researchers at the School of Medicine of the University of Washington found that nanoparticles could carry a toxin found in bee venom and were able to destroy human immunodeficiency virus (HIV) and didn’t harm the surrounding cells. They plan to develop a vaginal gel that can be used as a preventive measure to stop the initial infection.

Nanoparticles (purple) carrying melittin (green) fuse with HIV (small circles with spiked outer ring), destroying the virus’s protective envelope. Molecular bumpers (small red ovals) prevent the nanoparticles from harming the body’s normal cells, which are much larger in size. 

Targeted drug delivery can also be achieved by using magnetic nanoparticles are coated with certain biocompatible polymers, coupled with anticancer drugs and later guided by an external magnet to the desired organ.

Nanoparticles and you

Not many people guess that I'm a chemist. Yes, I even have a PhD that I just finished at the University of Birmingham (UK). I want to share an article that I wrote for www.satnavmag.org (Satnav magazine, a student run scientific magazine for the general public), it was published in July 2010.

Nanoparticles and you

What comes to mind when you hear the word nanoparticles? Some people might think of killer nanobots that will attack the planet, such as in The Prey by Michael Crichton, where they infect our brains and create a zombie infested world. The truth is far from that. In actual fact, nanoparticles are all around us right now, found in some of the things that we use every day.

So what are they?

Nanoparticles are usually defined as particles that range between 1 and 100 nm in size. A nanometre (nm) is one thousand millionth of a metre or 0.000000009 m, so it is pretty small! To illustrate this, the size of a human hair is between 25000 nm and 180000 nm wide, and bacteria are around 100 nm in diameter. Approximately ten hydrogen atoms in a line make up one nanometre.

How long have they been around?

Nanoparticles have been used for a very long time. It is just that we have only recently begun to understand what they are. Gold nanoparticles, which are red when they are as small as nanometres, were used in the past to stain glass. Medieval artisans made stained glass by mixing gold chloride into molten glass. They created tiny gold spheres that absorbed and reflected sunlight in a way that produced a variety of colours, without truly knowing what they were making. The artisans knew that by putting varying and tiny amounts of gold and silver in the glass, they could produce the effects found in stained-glass windows.

The Lycurgus Cup, which was made by the Romans, dates to the fourth century AD (Shown bellow). When viewed in reflected light (in daylight), it appears green, and when a light is shone into the cup and transmitted through the glass, it appears red.

The Lycurgus Cup from Roman times containing gold nanoparticles exhibited at the British

Museum, here displayed under different light sources.

When were nanoparticles first synthesised? 

Nanoparticles were first synthesised by Anthony Turkevich in the early 1950s, who incidentally was the same man that first determined the composition of the moon’s surface. Ever since then they have been widely used as contrast agents for electron microscopy (used during imaging examinations to highlight specific parts of the body and make them easier to see), cancer research and as carriers for drugs.

Silver antibacterial nanoparticles

Silver nanoparticles are widely used because of their antibacterial properties; silver acts against the bacteria by destroying or deactivating the enzymes that allow oxygen intake of the organism, and by destroying the cell membrane. As a result, the organism’s DNA cannot make replicas of itself, let alone create possible resistant strains. Silver nanoparticles are also non-toxic and don’t suppress the immune system. Socks, paints, bandages, and food containers incorporate nanosilver to exploit its antimicrobial properties. In clothing such as socks, nanosilver may restrict the growth of pungent bacteria.

Nanoparticles in clothes

Garments coated by silver, gold and palladium nanoparticles were shown at a fashion show in New York in 2007. The work was performed by designer Olivia Ong (Department of Fiber Science and Apparel Design from the College of Human Ecology), and the nanoparticle coated fabrics were made by Professor Juan Hinostroza.

One garment is claimed to prevent colds and flu and never needs washing (as bellow on the left of the image), and another destroys harmful gases and protects the wearer from smog and air pollution (as shown below on the right of the image). 

The dress (left) is made of cotton covered with silver nanoparticles that can deactivate bacteria. The hood, sleeves and pockets of the jacket (right) contain palladium nanoparticles that act as catalysts to reduce the negative effects of pollution.

Dipping positively charged cotton into a negatively charged silver nanoparticle solution resulted in the particles clinging to the cotton fibers. Firstly, positively charged cotton fibers were made by using ammonium and epoxy based reactions, which served to induce positive ionization. The silver particles, which are about 10-20 nanometres across, were synthesized in citric acid which prevented the nanoparticles from sticking together. The resultant colors are not the product of dyes, but are instead reflections of manipulation of particle size or arrangement. The problem with these types of fabrics is their price; for 90 cm2 of the fabric you would have to shell out 10,000 American dollars!

Nanoparticles in appliances 

In addition, Samsung has incorporated silver nanoparticles into a washing machine, which is known to release the particles during washing. They penetrate deeply into all kinds of fabrics, creating a protecting coat of sterilisation for a maximum of 99.99% disinfection, as well as an added antibacterial effect which can last for up to 30 days after washing. These nanoparticles are also used in fridges and air-conditioning, in order to prevent bad smells.

Other uses

Another commonly used nanoparticle is silicon oxide. Silicon oxide nanoparticles are used in the cosmetic industry, for biomedical applications and also in solar cells. Cerium oxide nanoparticles have recently been used in the petrol industry where they are added to diesel to reduce fuel consumption, greenhouse gas emissions (CO2), and particulate emissions.

Nanoparticles of iron oxide are very interesting because of their magnetic properties, and are widely used for medical applications. Over 300 sun creams in the market today contain titanium oxide and zinc oxide nanoparticles. By replacing traditional forms of ZnO and TiO2 with nanoparticles of these substances, manufacturers can reduce the visibility of the cream paving the way for ‘invisible’ sun cream.

What are the effects of nanoparticle use?

One of the biggest issues with nanoparticles is their possible toxicity and effect on the environment after they have been disposed. Regulatory bodies in the U.S. and Europe have started dealing with the potential risks

posed by nanoparticles, however neither engineered nanoparticles, nor the products and materials that contain them are subject to any special regulation regarding production, handling or labelling. It is therefore highly important to study the adverse effects and to both quantify and minimize them, both for environmental protection and to ensure the long term sustainability of the nanotechnology industry, along with its associated benefits. A lot of research is being done at the moment to assess those effects on humans, animals and the environment. Every day new uses for these tiny particles are found, and soon they may play a much bigger part in our lives than could have ever have been previously imagined.