Space & Innovation

Silver Nanoparticles May Harm Humans and Wildlife

Unhealthy reactions in human intestinal cells and aquatic algae have been documented after exposure to silver nanoparticles. Continue reading →

Microscopic bits of silver, known as nanoparticles, now appear as an anti-microbial ingredient in a wide variety of consumer products.

However, a growing body of evidence tarnishes silver nanoparticles' reputation. Studies published this year documented unhealthy reactions in human intestinal cells and aquatic algae after exposure to silver nanoparticles, reported Inside Science.

Photos: How Nanotech Can Make a Better You

Manufacturers now use silver nanoparticles in everything from skin creams to little black dresses to food containers. Commercial aliases for the nanoparticles include colloidal silver and nanosilver.

In 2013, the Environmental Protection Agency proposed registration of a pesticide containing silver nanoparticles. Consumers may benefit from the silver specks' ability to inhibit the growth of bacteria, fungus and other microorganisms, including disease-causing Escherichia coli and Staphylococcus aureus, according to numerous studies.

However, silver nanoparticles might harm more than microorganisms. Inside Science pointed to two recent studies that suggested nanosilver can be harmful.

Nanoparticle Safety Still Unknown

In a study from January, algae (Chlamydomonas reinhardtii) reacted negatively to nanosilver. The algae's rates of photosynthesis and levels of ATP, an energy storage and transport molecule, plummeted after exposure. The algae then mounted a defensive response to cleanse itself of the nanosilver and fight damage caused by the particles. The Proceedings of the National Academy of Sciences published the results.

Silver nanoparticles' tiny size allows them to enter parts of living things bodies that other molecules can't reach. The other study mentioned by Inside Science and published in February by ACS Nano, found that human intestinal cells reacted negatively to silver nanoparticles of different sizes.

Smaller particles (20 nanometers) could enter cells and directly damaged the internal workings, while larger particles (100 nanometers) acted indirectly by influencing protein production and enzyme activity.

Better Condoms Through Nanotechnology

The danger is that nanosilver may be entering the environment now, yet we don't know how it will affect living things in the long term. Scientists do know that various forms of silver, including nanoparticles, can be toxic to animals, including rainbow trout and rats, in laboratory experiments.

Photo: Nearly pure silver foil in a bottle. Credit: JanDerChemiker, Wikimedia Commons.

Sept. 27, 2011 --

In the popular "Deus Ex" video game series, nanotechnology can turn an average government agent into a bionic superman. In fact, nanotech augmentations in the human body aren't just fun and games. Real-life applications will most likely become reality a lot sooner than you think. In 2007, the world's first online inventory of nanotech products, Project on Emerging Nanotechnologies, found that nearly 500 products, including food, clothing and cosmetics, employed nanotechnology. In this slide show, explore how nanotech can make you stronger, tap into your brain and more.

WATCH: NANOTECH REWARDS

If you're too busy to make it to the gym, nanotechnology could be a way to get fit without having to spend hours toiling away on machines. In fact, technology can take you a lot further than any free-weight or cardio regimen. In 2006, researchers at the University of Texas at Dallas reported in the journal Science that they had created alcohol- and hydrogen-fueled artificial muscles 100 times stronger and capable of 100 times more work than natural muscles. Functioning as both muscles and fuel cells, the technology has a range of applications from artificial limbs to autonomous robots.

SCIENCE CHANNEL: Take the Nanotechnology Quiz

If nanotechnology can make you stronger, could it also make you smarter? Scientists aren't quite there yet, but nanotechnology applied to brain implants could treat a range of conditions from deafness to blindness to Parkinson's disease and more, according to biomedical engineers from the University of Michigan. Nanotechnology could also be used to tap into the mind, and read and write information directly into the brain. In an unusual twist, the research was undertaken by telecommunications engineers at Nippon Telegraph and Telephone.

Contact lenses with visual displays may seem like the kind of technology you only see in a movie. But researchers at the University of Washington have started laying the groundwork by building a contact lens with internal circuitry. Using wires made of metal only a few nanometers thick, the technology is placed in a contact lens rather than an implant, making use of the bionic eye much easier. In this photo, the contact lens has been affixed to a rabbit. The researchers believe they would quickly be able to introduce a visual display, but it wouldn't be more than a few pixels in the near future.

Tired of having to find an electrical outlet or a USB cable every time you need to charge your cell phone? With nanotechnology, you can become a walking battery. Using nanowires to recover wasted heat energy from the body, which is then converted into electrical power, researchers with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and the University of California at Berkeley have developed an entirely means of charging personal electronics. The same technology could be used to convert heat from other sources into electrical energy. As reported in the journal Nature, approximately 15 trillion watts of heat energy produced by engine and steam- and gas-powered turbines is lost to the environment.

Recovering from injuries to skin and muscle tissue can take weeks. Trauma to the brain or central nervous system can be irreversible. But with nanomedicine, a nanoparticle-infused hydrogel could heal brain and bone injuries by creating new blood vessels and encouraging stem cells to replace dead tissue. Developed by scientists from Clemson University, the gel still needs several more years of animal testing before human trials can begin. Injuries involving nerve damage or the spinal cord are among the most difficult to treat. But nanotechnology could open the door to rebuilding damaged nerve cells. Although regenerating nerve cells is the ultimate goal, researchers have so far been able to develop the scaffolding necessary to rebuild nerves following damage. The technique, a nanotechnology-infused stem cell treatment developed by David Nisbet of Monash University, could also aid in the treatment of Parkinson's disease.

Besides treating immediate injury, researchers are also exploring uses of nanotechnology to fight the effects of aging and to promote longer life. By using a breakthrough nanogel to stimulate stem cells, Northwestern University scientists found that they can regenerate lost cartilage in joints. As adults age, they start to lose their cartilege, a painful condition for which there is little effective treatment. A separate study undertaken by researchers at the University of Central Florida (UCF) found that using an industrial nanomaterial, they can triple or even quadruple the lives of brain cells. This could lead people "live longer and with fewer age-related health problems," according to a UCF press release about the study.

With more than an estimated 1.5 million new cancer patients this year alone, it's no surprise that one of the more promising applications of nanotechnology is in the detection, monitoring and treatment of various forms of cancer. From targeted drug delivery to direct attacks of "nanoworms" on tumor growths, researchers working within the field of nanomedicine are using the technology to attack cancer cells with unprecedented precision.

WATCH: NANOTECH RISKS