Category Archives: Nano Medicine

Uses of silver to establish the diagnosis, prognosis, treatment, and prevention of disease

The medical uses of silver include its use in wound dressings, creams, and as an antibiotic coating on medical devices.[1][2][3] Wound dressings containing silver sulfadiazine or silver nanomaterials may be used to treat external infections.[4][5][6] The limited evidence available shows that silver coatings on endotracheal breathing tubes may reduce the incidence of ventilator-associated pneumonia.[7] There is tentative evidence that using silver-alloy indwelling catheters for short-term catheterizing will reduce the risk of catheter-acquired urinary tract infections.[8][9][10]

Silver generally has low toxicity, and minimal risk is expected when silver is used in approved medical applications.[11] Alternative medicine products such as colloidal silver are not safe or effective.[12][13][14][15][16]

Silver and most silver compounds have an oligodynamic effect and are toxic for bacteria, algae, and fungi in vitro. The antibacterial action of silver is dependent on the silver ion.[11] The effectiveness of silver compounds as an antiseptic is based on the ability of the biologically active silver ion (Ag+) to irreversibly damage key enzyme systems in the cell membranes of pathogens.[11] The antibacterial action of silver has long been known to be enhanced by the presence of an electric field. Applying an electric current across silver electrodes enhances antibiotic action at the anode, likely due to the release of silver into the bacterial culture.[17] The antibacterial action of electrodes coated with silver nanostructures is greatly improved in the presence of an electric field.[18]

Silver, used as a topical antiseptic, is incorporated by bacteria it kills. Thus dead bacteria may be the source of silver that may kill additional bacteria.[19]

Silver sulfadiazine (SSD) is a topical antibiotic used in partial thickness and full thickness burns to prevent infection.[3][20] It was discovered in the 1960s,[21] and was the standard topical antimicrobial for burn wounds for decades.[22][23]

However systemic reviews in 2014, 2017 and 2018 concluded that more modern treatments, both with and without silver, show better results for wound healing and infection-prevention than silver sulfadiazine,[24][25][26] and therefore SSD is no longer generally recommended.[27][28]

It is on the World Health Organization's List of Essential Medicines.[29] The US Food and Drug Administration (FDA) approved a number of topical preparations of silver sulfadiazine for treatment of second-degree and third-degree burns.[30]

A 2018 Cochrane review found that silver-containing dressings may increase the probability of healing for venous leg ulcers.[31] A 2017 meta-analysis of clinical studies over the period of 20002015 concluded that "the evidence base for silver in wound management is significantly better than perceived in the current scientific debate" and that, if applied selectively and for short periods of time, silver has antimicrobial effects, produces an improvement in quality of life and shows good cost-effectiveness.[32] A 2014 data set from a recent meta-analysis concluded that the use of silver dressings improves healing time, and can lead to overall cost savings compared with treatment with non-silver dressings. It also found that patients who had been treated with silver dressings had a faster wound closure compared with patients who had been treated with non-silver dressings.[33] A 2013 meta-analysis of randomised controlled trials found statistically significant evidence to support the use of Biatain silver dressings in treating venous leg ulcers.[34]

A number of wound dressings containing silver as an anti-bacterial have been cleared by the U.S. Food and Drug Administration (FDA).[35][36][37][38] However, silver-containing dressings may cause staining, and in some cases tingling sensations as well.[39]

A 2015 systematic review concluded that the limited evidence available indicates that using silver-coated endotracheal breathing tubes reduces the risk of contracting ventilator-associated pneumonia (VAP), especially during the initial days of utilisation.[40] A 2014 study concluded that using silver-coated endotracheal tubes will help to prevent VAP and that this may save on hospital costs.[41] A 2012 systematic review of randomized controlled trials concluded that the limited evidence available indicates that using silver-coated endotracheal tubes will reduce the incidence of ventilator-associated pneumonia, microbiologic burden, and device-related adverse events among adult patients.[42] Another 2012 review agreed that the use of silver-coated endotracheal tubes reduces the prevalence of VAP in intubated patients, but cautioned that this on its own is not sufficient to prevent infection. They also suggested that more research is needed to establish the cost-effectiveness of the treatment.[43] Another 2012 study agreed that there is evidence that endotracheal tubes coated with silver may reduce the incidence of ventilator associated pneumonia (VAP) and delay its onset, but concluded that no benefit was seen in the duration of intubation, the duration of stay in intensive care or the mortality rate. They also raised concerns surrounding the unblinded nature of some of the studies then available.[7]

The U.S. Food and Drug Administration in 2007 cleared an endotracheal tube with a fine coat of silver to reduce the risk of ventilator-associated pneumonia.[44]

A 2014 systemic review concluded that using silver alloy-coated catheters showed no significant difference in incidences of symptomatic Catheter-Associated Urinary Tract Infections (CAUTI) versus using standard catheters, although silver-alloy catheters seemed to cause less discomfort to patients.[45] These catheters are associated with greater cost than other catheters.[45] A 2014 Multicenter Cohort Study found that using a silver-alloy hydrogel urinary catheter did reduce symptomatic Catheter-Associated Urinary Tract Infection (CAUTI) occurrences as defined by both NHSN and clinical criteria.[8] A 2011 critical analysis of eight studies found a consistent pattern which supported using silver-alloy urinary catheters over uncoated catheters to reduce infections in adult patients, and concluded that using silver-alloy catheters would significantly improve patient care.[9] A 2007 systemic review concluded that using silver-alloy indwelling catheters for short-term catheterizing will reduce the risk of catheter-acquired urinary tract infection, but called for further studies to evaluate the economic benefits of using the expensive silver alloy-catheters.[10] Two systemic reviews in 2004 found that using silver-alloy catheters reduced asymptomatic and symptomatic bacteriuria more than standard catheters, for patients who were catheterised for a short time.[46] A 2000 randomized crossover study found that using the more expensive silver-coated catheter may result in cost savings by preventing nosocomial UTI infections,[47] and another 2000 study found that using silver alloy catheters for short-term urinary catheterization reduces the incidence of symptomatic UTI and bacteremia compared with standard catheters, and may thus yield cost savings.[48]

A 2017 study found that a combination of chlorhexidine and silver-sulfadiazine (CSS) used to coat central venous catheters (CVC) reduces the rate of catheter-related bloodstream infections.[49] However, they also found that the efficacy of the CSS-CVC coating was progressively eroded by blood-flow, and that the antibacterial function was lost after 48 hours.

Research in 2018 into the treatment of central nervous system infections caused by free-living amoebae such as Naegleria fowleri and Acanthamoeba castellanii, tested the effectiveness of existing drugs as well as the effectiveness of the same drugs when they were conjugated with silver nanoparticles. In vitro tests demonstrated more potent amoebicidal effects for the drugs when conjugated with silver nanoparticles as compared to the same drugs when used alone. They also found that conjugating the drugs with silver nanoparticles enhanced their anti-acanthamoebic activity.[50]

Silver-halide imaging plates used with X-ray imaging were the standard before digital techniques arrived; these function essentially the same as other silver-halide photographic films, although for x-ray use the developing process is very simple and takes only a few minutes. Silver x-ray film remains popular for its accuracy, and cost effectiveness, particularly in developing countries, where digital X-ray technology is usually not available.[51]

Silver compounds have been used in external preparations as antiseptics, including both silver nitrate and silver proteinate, which can be used in dilute solution as eyedrops to prevent conjunctivitis in newborn babies. Silver nitrate is also sometimes used in dermatology in solid stick form as a caustic ("lunar caustic") to treat certain skin conditions, such as corns and warts.[52]

Silver nitrate is also used in certain laboratory procedures to stain cells. As it turns them permanently a dark-purple/black color, in doing so increasing individual cells' visibility under a microscope and allowing for differentiation between cells, or identification of irregularities. Silver is also used in bone prostheses and cardiac devices.[11] In reconstructive hip and knee surgery, silver-coated titanium prostheses are indicated in cases of recalcitrant prosthetic joint infections.[53] Silver diamine fluoride appears to be an effective intervention to reduce dental caries (tooth decay).[54][55] Silver is also a component in dental amalgam.

Silver acetate has been used as a potential aid to help stop smoking; a review of the literature in 2012, however, found no effect of silver acetate on smoking cessation at a six-month endpoint and if there is an effect it would be small.[56] Silver has also been used in cosmetics, intended to enhance antimicrobial effects and the preservation of ingredients.[57]

Though toxicity of silver is low, the human body has no biological use for silver and when inhaled, ingested, injected, or applied topically, silver will accumulate irreversibly in the body, particularly in the skin, and chronic use combined with exposure to sunlight can result in a disfiguring condition known as argyria in which the skin becomes blue or blue-gray.[11][58] Localized argyria can occur as a result of topical use of silver-containing creams and solutions, while the ingestion, inhalation, or injection can result in generalized argyria.[59][60] Preliminary reports of treatment with laser therapy have been reported. These laser treatments are painful and general anesthesia is required.[61][62] A similar laser treatment has been used to clear silver particles from the eye, a condition related to argyria called argyrosis.[63] The Agency for Toxic Substances and Disease Registry (ATSDR) describes argyria as a "cosmetic problem".[64]

One incident of argyria came to the public's attention in 2008, when a man named Paul Karason, whose skin turned blue from using colloidal silver for over 10 years to treat dermatitis, appeared on NBC's "Today" show. Karason died in 2013 at the age of 62 after a heart attack.[65] Another example is Montana politician Stan Jones whose purposeful consumption of colloidal silver was a self-prescribed measure he undertook in response to his fears that the Y2K problem would make antibiotics unavailable, an event that did not occur.[66]

Colloidal silver may interact with some prescription medications, reducing the absorption of some antibiotics and thyroxine, among others.[67]

Some people are allergic to silver, and the use of treatments and medical devices containing silver is contraindicated for such people.[11] Although medical devices containing silver are widely used in hospitals, no thorough testing and standardization of these products has yet been undertaken.[68]

Electrolytically dissolved silver has been used as a water disinfecting agent, for example, the drinking water supplies of the Russian Mir orbital station and the International Space Station.[69] Many modern hospitals filter hot water through copper-silver filters to defeat MRSA and legionella infections.[70]:29 The World Health Organization (WHO) includes silver in a colloidal state produced by electrolysis of silver electrodes in water, and colloidal silver in water filters as two of a number of water disinfection methods specified to provide safe drinking water in developing countries.[71] Along these lines, a ceramic filtration system coated with silver particles has been created by Ron Rivera of Potters for Peace and used in developing countries for water disinfection (in this application the silver inhibits microbial growth on the filter substrate, to prevent clogging, and does not directly disinfect the filtered water).[72][73][74]

A bottle of colloidal silver

Colloidal silver (a colloid consisting of silver particles suspended in liquid) and formulations containing silver salts were used by physicians in the early 20th century, but their use was largely discontinued in the 1940s following the development of modern antibiotics.[58][78] Since about 1990, there has been a resurgence of the promotion of colloidal silver as a dietary supplement,[52] marketed with claims of it being an essential mineral supplement, or that it can prevent or treat numerous diseases, such as cancer, diabetes, arthritis, HIV/AIDS, herpes,[58] and tuberculosis.[52][79][80] No medical evidence supports the effectiveness of colloidal silver for any of these claimed indications.[52][77][81] Silver is not an essential mineral in humans; there is no dietary requirement for silver, and hence, no such thing as a silver "deficiency".[52] There is no evidence that colloidal silver treats or prevents any medical condition, and it can cause serious and potentially irreversible side effects such as argyria.[52]

In August 1999, the U.S. FDA banned colloidal silver sellers from claiming any therapeutic or preventive value for the product,[77] although silver-containing products continue to be promoted as dietary supplements in the U.S. under the looser regulatory standards applied to supplements.[77] The FDA has issued numerous warning letters to Internet sites that have continued to promote colloidal silver as an antibiotic or for other medical purposes.[82][83][84] Despite the efforts of the FDA, silver products remain widely available on the market today. A review of websites promoting nasal sprays containing colloidal silver suggested that information about silver-containing nasal sprays on the Internet is misleading and inaccurate.[85] Colloidal silver is also sold in some topical cosmetics, as well as some toothpastes, which are regulated by the FDA as cosmetics (other than drug ingredients making medical claims).[86]

In 2002, the Australian Therapeutic Goods Administration (TGA) found there were no legitimate medical uses for colloidal silver and no evidence to support its marketing claims.[87] The U.S. National Center for Complementary and Integrative Health (NCCIH) warns that marketing claims about colloidal silver are scientifically unsupported, that the silver content of marketed supplements varies widely, and that colloidal silver products can have serious side effects such as argyria.[52]In 2009, the USFDA issued a consumer advisory warning about the potential adverse effects of colloidal silver, and said that "there are no legally marketed prescription or over-the-counter (OTC) drugs containing silver that are taken by mouth".[88] Quackwatch states that colloidal silver dietary supplements have not been found safe or effective for the treatment of any condition.[89] Consumer Reports lists colloidal silver as a "supplement to avoid", describing it as "likely unsafe".[90] The Los Angeles Times stated that "colloidal silver as a cure-all is a fraud with a long history, with quacks claiming it could cure cancer, AIDS, tuberculosis, diabetes, and numerous other diseases".[91]

It may be illegal to market as preventing or treating cancer, and in some jurisdictions illegal to sell colloidal silver for consumption.[75] In 2015 an English man was prosecuted and found guilty under the Cancer Act 1939 for selling colloidal silver with claims it could treat cancer.[92]

The US Food and Drug Administration has issued warning letters to firms including colloidal silver marketers for selling products with false and misleading claims to prevent, treat, mitigate, diagnose or cure coronavirus disease 2019 (COVID-19).[93]

In 2020, televangelist felon Jim Bakker was sued by the Missouri Attorney General (AG) for marketing colloidal silver products and making false claims about their effectiveness against COVID-19. The Attorney General of New York sent a cease and desist order to Bakker and others about peddling the unproven products that was compared to selling "snake oil", and the Food and Drug Administration also warned Bakker about his actions.[94]

Controversial web show host, podcaster and conspiracy theorist Alex Jones was also warned by the New York Attorney General's office to stop marketing his colloidal silver infused products (toothpaste, mouthwash, dietary supplements, etc.) because he made unproven claims of its ability to fend off COVID-19.[95]

Hippocrates in his writings discussed the use of silver in wound care.[96] At the beginning of the twentieth century surgeons routinely used silver sutures to reduce the risk of infection.[96][97] In the early 20th century, physicians used silver-containing eyedrops to treat ophthalmic problems,[98] for various infections,[99][100] and sometimes internally for diseases such as tropical sprue,[101] epilepsy, gonorrhea, and the common cold.[52][78] During World War I, soldiers used silver leaf to treat infected wounds.[96][102]

In the 1840s, founder of gynecology J. Marion Sims employed silver wire, which he had a jeweler fashion, as a suture in gynecological surgery. This produced very favorable results when compared with its predecessors, silk and catgut.[97]

Prior to the introduction of modern antibiotics, colloidal silver was used as a germicide and disinfectant.[103] With the development of modern antibiotics in the 1940s, the use of silver as an antimicrobial agent diminished, although it retains some use in medicinal compounds today. Silver sulfadiazine (SSD) is a compound containing silver and the antibiotic sodium sulfadiazine, which was developed in 1968.[68]

The National Health Services in the UK spent about 25 million on silver-containing dressings in 2006. Silver-containing dressings represent about 14% of the total dressings used and about 25% of the overall wound dressing costs.[104]

Concerns have been expressed about the potential environmental cost of manufactured silver nanomaterials in consumer applications being released into the environment, for example that they may pose a threat to benign soil organisms.[105]

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Medical uses of silver - Wikipedia

Nanotechnology, the manipulation of matter at the atomic and molecular scale to create materials with remarkably varied and new properties, is a rapidly expanding area of research with huge potential in many sectors, ranging from healthcare to construction and electronics. In medicine, it promises to revolutionize drug delivery, gene therapy, diagnostics, and many areas of research, development and clinical application.

This article does not attempt to cover the whole field, but offers, by means of some examples, a few insights into how nanotechnology has the potential to change medicine, both in the research lab and clinically, while touching on some of the challenges and concerns that it raises.

The prefix nano stems from the ancient Greek for dwarf. In science it means one billionth (10 to the minus 9) of something, thus a nanometer (nm) is is one billionth of a meter, or 0.000000001 meters. A nanometer is about three to five atoms wide, or some 40,000 times smaller than the thickness of human hair. A virus is typically 100 nm in size.

The ability to manipulate structures and properties at the nanoscale in medicine is like having a sub-microscopic lab bench on which you can handle cell components, viruses or pieces of DNA, using a range of tiny tools, robots and tubes.

Therapies that involve the manipulation of individual genes, or the molecular pathways that influence their expression, are increasingly being investigated as an option for treating diseases. One highly sought goal in this field is the ability to tailor treatments according to the genetic make-up of individual patients.

This creates a need for tools that help scientists experiment and develop such treatments.

Imagine, for example, being able to stretch out a section of DNA like a strand of spaghetti, so you can examine or operate on it, or building nanorobots that can walk and carry out repairs inside cell components. Nanotechnology is bringing that scientific dream closer to reality.

For instance, scientists at the Australian National University have managed to attach coated latex beads to the ends of modified DNA, and then using an optical trap comprising a focused beam of light to hold the beads in place, they have stretched out the DNA strand in order to study the interactions of specific binding proteins.

Meanwhile chemists at New York University (NYU) have created a nanoscale robot from DNA fragments that walks on two legs just 10 nm long. In a 2004 paper published in the journal Nano Letters, they describe how their nanowalker, with the help of psoralen molecules attached to the ends of its feet, takes its first baby steps: two forward and two back.

One of the researchers, Ned Seeman, said he envisages it will be possible to create a molecule-scale production line, where you move a molecule along till the right location is reached, and a nanobot does a bit chemisty on it, rather like spot-welding on a car assembly line. Seemans lab at NYU is also looking to use DNA nanotechnology to make a biochip computer, and to find out how biological molecules crystallize, an area that is currently fraught with challenges.

The work that Seeman and colleagues are doing is a good example of biomimetics, where with nanotechnology they can imitate some of the biological processes in nature, such as the behavior of DNA, to engineer new methods and perhaps even improve them.

DNA-based nanobots are also being created to target cancer cells. For instance, researchers at Harvard Medical School in the US reported recently in Science how they made an origami nanorobot out of DNA to transport a molecular payload. The barrel-shaped nanobot can carry molecules containing instructions that make cells behave in a particular way. In their study, the team successfully demonstrates how it delivered molecules that trigger cell suicide in leukemia and lymphoma cells.

Nanobots made from other materials are also in development. For instance, gold is the material scientists at Northwestern University use to make nanostars, simple, specialized, star-shaped nanoparticles that can href=http://www.medicalnewstoday.com/articles/243856.php>deliver drugs directly to the nuclei of cancer cells. In a recent paper in the journal ACS Nano, they describe how drug-loaded nanostars behave like tiny hitchhikers, that after being attracted to an over-expressed protein on the surface of human cervical and ovarian cancer cells, deposit their payload right into the nuclei of those cells.

The researchers found giving their nanobot the shape of a star helped to overcome one of the challenges of using nanoparticles to deliver drugs: how to release the drugs precisely. They say the shape helps to concentrate the light pulses used to release the drugs precisely at the points of the star.

Scientists are discovering that protein-based drugs are very useful because they can be programmed to deliver specific signals to cells. But the problem with conventional delivery of such drugs is that the body breaks most of them down before they reach their destination.

But what if it were possible to produce such drugs in situ, right at the target site? Well, in a recent issue of Nano Letters, researchers at Massachusetts Institute of Technology (MIT) in the US show how it may be possible to do just that. In their proof of principle study, they demonstrate the feasibility of self-assembling nanofactories that make protein compounds, on demand, at target sites. So far they have tested the idea in mice, by creating nanoparticles programmed to produce either green fluorescent protein (GFP) or luciferase exposed to UV light.

The MIT team came up with the idea while trying to find a way to attack metastatic tumors, those that grow from cancer cells that have migrated from the original site to other parts of the body. Over 90% of cancer deaths are due to metastatic cancer. They are now working on nanoparticles that can synthesize potential cancer drugs, and also on other ways to switch them on.

Nanofibers are fibers with diameters of less than 1,000 nm. Medical applications include special materials for wound dressings and surgical textiles, materials used in implants, tissue engineering and artificial organ components.

Nanofibers made of carbon also hold promise for medical imaging and precise scientific measurement tools. But there are huge challenges to overcome, one of the main ones being how to make them consistently of the correct size. Historically, this has been costly and time-consuming.

But last year, researchers from North Carolina State University, revealed how they had developed a new method for making carbon nanofibers of specific sizes. Writing in ACS Applied Materials & Interfaces in March 2011, they describe how they managed to grow carbon nanofibers uniform in diameter, by using nickel nanoparticles coated with a shell made of ligands, small organic molecules with functional parts that bond directly to metals.

Nickel nanoparticles are particularly interesting because at high temperatures they help grow carbon nanofibers. The researchers also found there was another benefit in using these nanoparticles, they could define where the nanofibers grew and by correct placement of the nanoparticles they could grow the nanofibers in a desired specific pattern: an important feature for useful nanoscale materials.

Lead is another substance that is finding use as a nanofiber, so much so that neurosurgeon-to-be Matthew MacEwan, who is studying at Washington University School of Medicine in St. Louis, started his own nanomedicine company aimed at revolutionizing the surgical mesh that is used in operating theatres worldwide.

The lead product is a synthetic polymer comprising individual strands of nanofibers, and was developed to repair brain and spinal cord injuries, but MacEwan thinks it could also be used to mend hernias, fistulas and other injuries.

Currently, the surgical meshes used to repair the protective membrane that covers the brain and spinal cord are made of thick and stiff material, which is difficult to work with. The lead nanofiber mesh is thinner, more flexible and more likely to integrate with the bodys own tissues, says MacEwan. Every thread of the nanofiber mesh is thousands of times smaller than the diameter of a single cell. The idea is to use the nanofiber material not only to make operations easier for surgeons to carry out, but also so there are fewer post-op complications for patients, because it breaks down naturally over time.

Researchers at the Polytechnic Institute of New York University (NYU-Poly) have recently demonstrated a new way to make nanofibers out of proteins. Writing recently in the journal Advanced Functional Materials, the researchers say they came across their finding almost by chance: they were studying certain cylinder-shaped proteins derived from cartilage, when they noticed that in high concentrations, some of the proteins spontaneously came together and self-assembled into nanofibers.

They carried out further experiments, such as adding metal-recognizing amino acids and different metals, and found they could control fiber formation, alter its shape, and how it bound to small molecules. For instance, adding nickel transformed the fibers into clumped mats, which could be used to trigger the release of an attached drug molecule.

The researchers hope this new method will greatly improve the delivery of drugs to treat cancer, heart disorders and Alzheimers disease. They can also see applications in regeneration of human tissue, bone and cartilage, and even as a way to develop tinier and more powerful microprocessors for use in computers and consumer electronics.

Recent years have seen an explosion in the number of studies showing the variety of medical applications of nanotechnology and nanomaterials. In this article we have glimpsed just a small cross-section of this vast field. However, across the range, there exist considerable challenges, the greatest of which appear to be how to scale up production of materials and tools, and how to bring down costs and timescales.

But another challenge is how to quickly secure public confidence that this rapidly expanding technology is safe. And so far, it is not clear whether that is being done.

There are those who suggest concerns about nanotechnology may be over-exaggerated. They point to the fact that just because a material is nanosized, it does not mean it is dangerous, indeed nanoparticles have been around since the Earth was born, occurring naturally in volcanic ash and sea-spray, for example. As byproducts of human activity, they have been present since the Stone Age, in smoke and soot.

Of attempts to investigate the safety of nanomaterials, the National Cancer Institute in the US says there are so many nanoparticles naturally present in the environment that they are often at order-of-magnitude higher levels than the engineered particles being evaluated. In many respects, they point out, most engineered nanoparticles are far less toxic than household cleaning products, insecticides used on family pets, and over-the-counter dandruff remedies, and that for instance, in their use as carriers of chemotherapeutics in cancer treatment, they are much less toxic than the drugs they carry.

It is perhaps more in the food sector that we have seen some of the greatest expansion of nanomaterials on a commercial level. Although the number of foods that contain nanomaterials is still small, it appears set to change over the next few years as the technology develops. Nanomaterials are already used to lower levels of fat and sugar without altering taste, or to improve packaging to keep food fresher for longer, or to tell consumers if the food is spoiled. They are also being used to increase the bioavailablity of nutrients (for instance in food supplements).

But, there are also concerned parties, who highlight that while the pace of research quickens, and the market for nanomaterials expands, it appears not enough is being done to discover their toxicological consequences.

This was the view of a science and technology committee of the House of Lords of the British Parliament, who in a recent report on nanotechnology and food, raise several concerns about nanomaterials and human health, particularly the risk posed by ingested nanomaterials.

For instance, one area that concerns the committee is the size and exceptional mobility of nanoparticles: they are small enough, if ingested, to penetrate cell membranes of the lining of the gut, with the potential to access the brain and other parts of the body, and even inside the nuclei of cells.

Another is the solubility and persistence of nanomaterials. What happens, for instance, to insoluble nanoparticles? If they cant be broken down and digested or degraded, is there a danger they will accumulate and damage organs? Nanomaterials comprising inorganic metal oxides and metals are thought to be the ones most likely to pose a risk in this area.

Also, because of their high surface area to mass ratio, nanoparticles are highly reactive, and may for instance, trigger as yet unknown chemical reactions, or by bonding with toxins, allow them to enter cells that they would otherwise have no access to.

For instance, with their large surface area, reactivity and electrical charge, nanomaterials create the conditions for what is described as particle aggregation due to physical forces and particle agglomoration due to chemical forces, so that individual nanoparticles come together to form larger ones. This may lead not only to dramatically larger particles, for instance in the gut and inside cells, but could also result in disaggregation of clumps of nanoparticles, which could radically alter their physicochemical properties and chemical reactivity.

Such reversible phenomena add to the difficulty in understanding the behaviour and toxicology of nanomaterials, says the committee, whose overall conclusion is that neither Government nor the Research Councils are giving enough priority to researching the safety of nanotechnology, especially considering the timescale within which products containing nanomaterials may be developed.

They recommend much more research is needed to ensure that regulatory agencies can effectively assess the safety of products before they are allowed onto the market.

It would appear, therefore, whether actual or perceived, the potential risk that nanotechnology poses to human health must be investigated, and be seen to be investigated. Most nanomaterials, as the NCI suggests, will likely prove to be harmless.

But when a technology advances rapidly, knowledge and communication about its safety needs to keep pace in order for it to benefit, especially if it is also to secure public confidence. We only have to look at what happened, and to some extent is still happening, with genetically modified food to see how that can go badly wrong.

Written by Catharine Paddock PhD

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Nanotechnology In Medicine: Huge Potential, But What Are The Risks?

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After more than 20 years of basic nanoscience research andmore than fifteen years of focused R&D under the NNI, applications of nanotechnology are delivering in both expected and unexpected ways on nanotechnologys promise to benefit society.

Nanotechnology is helping to considerably improve, even revolutionize, many technology and industry sectors: information technology, homeland security, medicine, transportation, energy, food safety, and environmental science, among many others. Described below is a sampling of the rapidly growing list of benefits and applications of nanotechnology.

Many benefits of nanotechnology depend on the fact that it is possible to tailor the structures of materials at extremely small scales to achieve specific properties, thus greatly extending the materials science toolkit. Using nanotechnology, materials can effectively be made stronger, lighter, more durable, more reactive, more sieve-like, or better electrical conductors, among many other traits. Many everyday commercial products are currently on the market and in daily use that rely on nanoscale materials and processes:

Nanotechnology has greatly contributed to major advances in computing and electronics, leading to faster, smaller, and more portable systems that can manage and store larger and larger amounts of information. These continuously evolving applications include:

Nanotechnology is already broadening the medical tools, knowledge, and therapies currently available to clinicians. Nanomedicine, the application of nanotechnology in medicine, draws on the natural scale of biological phenomena to produce precise solutions for disease prevention, diagnosis, and treatment. Below are some examples of recent advances in this area:

Nanotechnology is finding application in traditional energy sources and is greatly enhancing alternative energy approaches to help meet the worlds increasing energy demands. Many scientists are looking into ways to develop clean, affordable, and renewable energy sources, along with means to reduce energy consumption and lessen toxicity burdens on the environment:

In addition to the ways that nanotechnology can help improve energy efficiency (see the section above), there are also many ways that it can help detect and clean up environmental contaminants:

Nanotechnology offers the promise of developing multifunctional materials that will contribute to building and maintaining lighter, safer, smarter, and more efficient vehicles, aircraft, spacecraft, and ships. In addition, nanotechnology offers various means to improve the transportation infrastructure:

Please visit the Environmental, Health, and Safety Issues and the Ethical, Legal, and Societal Issues pages on nano.gov to learn more about how the National Nanotechnology Initiative is committed to responsibly addressing these issues.

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Applications of Nanotechnology - National Nanotechnology Initiative

Field of applied science addressing the control of matter on atomic and (supra)molecular scales

Nanotechnology, also shortened to nanotech, is the use of matter on an atomic, molecular, and supramolecular scale for industrial purposes. The earliest, widespread description of nanotechnology referred to the particular technological goal of precisely manipulating atoms and molecules for fabrication of macroscale products, also now referred to as molecular nanotechnology.[1][2] A more generalized description of nanotechnology was subsequently established by the National Nanotechnology Initiative, which defined nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers. This definition reflects the fact that quantum mechanical effects are important at this quantum-realm scale, and so the definition shifted from a particular technological goal to a research category inclusive of all types of research and technologies that deal with the special properties of matter which occur below the given size threshold. It is therefore common to see the plural form "nanotechnologies" as well as "nanoscale technologies" to refer to the broad range of research and applications whose common trait is size.

Nanotechnology as defined by size is naturally broad, including fields of science as diverse as surface science, organic chemistry, molecular biology, semiconductor physics, energy storage,[3][4] engineering,[5] microfabrication,[6] and molecular engineering.[7] The associated research and applications are equally diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly,[8] from developing new materials with dimensions on the nanoscale to direct control of matter on the atomic scale.

Scientists currently debate the future implications of nanotechnology. Nanotechnology may be able to create many new materials and devices with a vast range of applications, such as in nanomedicine, nanoelectronics, biomaterials energy production, and consumer products. On the other hand, nanotechnology raises many of the same issues as any new technology, including concerns about the toxicity and environmental impact of nanomaterials,[9] and their potential effects on global economics, as well as speculation about various doomsday scenarios. These concerns have led to a debate among advocacy groups and governments on whether special regulation of nanotechnology is warranted.

The concepts that seeded nanotechnology were first discussed in 1959 by renowned physicist Richard Feynman in his talk There's Plenty of Room at the Bottom, in which he described the possibility of synthesis via direct manipulation of atoms.

The term "nano-technology" was first used by Norio Taniguchi in 1974, though it was not widely known. Inspired by Feynman's concepts, K. Eric Drexler used the term "nanotechnology" in his 1986 book Engines of Creation: The Coming Era of Nanotechnology, which proposed the idea of a nanoscale "assembler" which would be able to build a copy of itself and of other items of arbitrary complexity with atomic control. Also in 1986, Drexler co-founded The Foresight Institute (with which he is no longer affiliated) to help increase public awareness and understanding of nanotechnology concepts and implications.

The emergence of nanotechnology as a field in the 1980s occurred through convergence of Drexler's theoretical and public work, which developed and popularized a conceptual framework for nanotechnology, and high-visibility experimental advances that drew additional wide-scale attention to the prospects of atomic control of matter. In the 1980s, two major breakthroughs sparked the growth of nanotechnology in the modern era. First, the invention of the scanning tunneling microscope in 1981 which provided unprecedented visualization of individual atoms and bonds, and was successfully used to manipulate individual atoms in 1989. The microscope's developers Gerd Binnig and Heinrich Rohrer at IBM Zurich Research Laboratory received a Nobel Prize in Physics in 1986.[10][11] Binnig, Quate and Gerber also invented the analogous atomic force microscope that year.

Second, fullerenes were discovered in 1985 by Harry Kroto, Richard Smalley, and Robert Curl, who together won the 1996 Nobel Prize in Chemistry.[12][13] C60 was not initially described as nanotechnology; the term was used regarding subsequent work with related carbon nanotubes (sometimes called graphene tubes or Bucky tubes) which suggested potential applications for nanoscale electronics and devices. The discovery of carbon nanotubes is largely attributed to Sumio Iijima of NEC in 1991,[14] for which Iijima won the inaugural 2008 Kavli Prize in Nanoscience.

A nanolayer-base metalsemiconductor junction (MS junction) transistor was initially proposed by A. Rose in 1960, and fabricated by L. Geppert, Mohamed Atalla and Dawon Kahng in 1962.[15] Decades later, advances in multi-gate technology enabled the scaling of metaloxidesemiconductor field-effect transistor (MOSFET) devices down to nano-scale levels smaller than 20nm gate length, starting with the FinFET (fin field-effect transistor), a three-dimensional, non-planar, double-gate MOSFET. At UC Berkeley, a team of researchers including Digh Hisamoto, Chenming Hu, Tsu-Jae King Liu, Jeffrey Bokor and others fabricated FinFET devices down to a 17nm process in 1998, then 15nm in 2001, and then 10nm in 2002.[16]

In the early 2000s, the field garnered increased scientific, political, and commercial attention that led to both controversy and progress. Controversies emerged regarding the definitions and potential implications of nanotechnologies, exemplified by the Royal Society's report on nanotechnology.[17] Challenges were raised regarding the feasibility of applications envisioned by advocates of molecular nanotechnology, which culminated in a public debate between Drexler and Smalley in 2001 and 2003.[18]

Meanwhile, commercialization of products based on advancements in nanoscale technologies began emerging. These products are limited to bulk applications of nanomaterials and do not involve atomic control of matter. Some examples include the Silver Nano platform for using silver nanoparticles as an antibacterial agent, nanoparticle-based transparent sunscreens, carbon fiber strengthening using silica nanoparticles, and carbon nanotubes for stain-resistant textiles.[19][20]

Governments moved to promote and fund research into nanotechnology, such as in the U.S. with the National Nanotechnology Initiative, which formalized a size-based definition of nanotechnology and established funding for research on the nanoscale, and in Europe via the European Framework Programmes for Research and Technological Development.

By the mid-2000s new and serious scientific attention began to flourish. Projects emerged to produce nanotechnology roadmaps[21][22] which center on atomically precise manipulation of matter and discuss existing and projected capabilities, goals, and applications.

In 2006, a team of Korean researchers from the Korea Advanced Institute of Science and Technology (KAIST) and the National Nano Fab Center developed a 3nm MOSFET, the world's smallest nanoelectronic device. It was based on gate-all-around (GAA) FinFET technology.[23][24]

Over sixty countries created nanotechnology research and development (R&D) government programs between 2001 and 2004. Government funding was exceeded by corporate spending on nanotechnology R&D, with most of the funding coming from corporations based in the United States, Japan and Germany. The top five organizations that filed the most intellectual patents on nanotechnology R&D between 1970 and 2011 were Samsung Electronics (2,578 first patents), Nippon Steel (1,490 first patents), IBM (1,360 first patents), Toshiba (1,298 first patents) and Canon (1,162 first patents). The top five organizations that published the most scientific papers on nanotechnology research between 1970 and 2012 were the Chinese Academy of Sciences, Russian Academy of Sciences, Centre national de la recherche scientifique, University of Tokyo and Osaka University.[25]

Nanotechnology is the engineering of functional systems at the molecular scale. This covers both current work and concepts that are more advanced. In its original sense, nanotechnology refers to the projected ability to construct items from the bottom up, using techniques and tools being developed today to make complete, high-performance products.

One nanometer (nm) is one billionth, or 109, of a meter. By comparison, typical carbon-carbon bond lengths, or the spacing between these atoms in a molecule, are in the range 0.120.15 nm, and a DNA double-helix has a diameter around 2nm. On the other hand, the smallest cellular life-forms, the bacteria of the genus Mycoplasma, are around 200nm in length. By convention, nanotechnology is taken as the scale range 1 to 100 nm following the definition used by the National Nanotechnology Initiative in the US. The lower limit is set by the size of atoms (hydrogen has the smallest atoms, which are approximately a quarter of a nm kinetic diameter) since nanotechnology must build its devices from atoms and molecules. The upper limit is more or less arbitrary but is around the size below which the phenomena not observed in larger structures start to become apparent and can be made use of in the nano device.[26] These new phenomena make nanotechnology distinct from devices which are merely miniaturised versions of an equivalent macroscopic device; such devices are on a larger scale and come under the description of microtechnology.[27]

To put that scale in another context, the comparative size of a nanometer to a meter is the same as that of a marble to the size of the earth.[28] Or another way of putting it: a nanometer is the amount an average man's beard grows in the time it takes him to raise the razor to his face.[28]

Two main approaches are used in nanotechnology. In the "bottom-up" approach, materials and devices are built from molecular components which assemble themselves chemically by principles of molecular recognition.[29] In the "top-down" approach, nano-objects are constructed from larger entities without atomic-level control.[30]

Areas of physics such as nanoelectronics, nanomechanics, nanophotonics and nanoionics have evolved during the last few decades to provide a basic scientific foundation of nanotechnology.

Several phenomena become pronounced as the size of the system decreases. These include statistical mechanical effects, as well as quantum mechanical effects, for example the "quantum size effect" where the electronic properties of solids are altered with great reductions in particle size. This effect does not come into play by going from macro to micro dimensions. However, quantum effects can become significant when the nanometer size range is reached, typically at distances of 100 nanometers or less, the so-called quantum realm. Additionally, a number of physical (mechanical, electrical, optical, etc.) properties change when compared to macroscopic systems. One example is the increase in surface area to volume ratio altering mechanical, thermal and catalytic properties of materials. Diffusion and reactions at nanoscale, nanostructures materials and nanodevices with fast ion transport are generally referred to nanoionics. Mechanical properties of nanosystems are of interest in the nanomechanics research. The catalytic activity of nanomaterials also opens potential risks in their interaction with biomaterials.

Materials reduced to the nanoscale can show different properties compared to what they exhibit on a macroscale, enabling unique applications. For instance, opaque substances can become transparent (copper); stable materials can turn combustible (aluminium); insoluble materials may become soluble (gold). A material such as gold, which is chemically inert at normal scales, can serve as a potent chemical catalyst at nanoscales. Much of the fascination with nanotechnology stems from these quantum and surface phenomena that matter exhibits at the nanoscale.[31]

Modern synthetic chemistry has reached the point where it is possible to prepare small molecules to almost any structure. These methods are used today to manufacture a wide variety of useful chemicals such as pharmaceuticals or commercial polymers. This ability raises the question of extending this kind of control to the next-larger level, seeking methods to assemble these single molecules into supramolecular assemblies consisting of many molecules arranged in a well defined manner.

These approaches utilize the concepts of molecular self-assembly and/or supramolecular chemistry to automatically arrange themselves into some useful conformation through a bottom-up approach. The concept of molecular recognition is especially important: molecules can be designed so that a specific configuration or arrangement is favored due to non-covalent intermolecular forces. The WatsonCrick basepairing rules are a direct result of this, as is the specificity of an enzyme being targeted to a single substrate, or the specific folding of the protein itself. Thus, two or more components can be designed to be complementary and mutually attractive so that they make a more complex and useful whole.

Such bottom-up approaches should be capable of producing devices in parallel and be much cheaper than top-down methods, but could potentially be overwhelmed as the size and complexity of the desired assembly increases. Most useful structures require complex and thermodynamically unlikely arrangements of atoms. Nevertheless, there are many examples of self-assembly based on molecular recognition in biology, most notably WatsonCrick basepairing and enzyme-substrate interactions. The challenge for nanotechnology is whether these principles can be used to engineer new constructs in addition to natural ones.

Molecular nanotechnology, sometimes called molecular manufacturing, describes engineered nanosystems (nanoscale machines) operating on the molecular scale. Molecular nanotechnology is especially associated with the molecular assembler, a machine that can produce a desired structure or device atom-by-atom using the principles of mechanosynthesis. Manufacturing in the context of productive nanosystems is not related to, and should be clearly distinguished from, the conventional technologies used to manufacture nanomaterials such as carbon nanotubes and nanoparticles.

When the term "nanotechnology" was independently coined and popularized by Eric Drexler (who at the time was unaware of an earlier usage by Norio Taniguchi) it referred to a future manufacturing technology based on molecular machine systems. The premise was that molecular-scale biological analogies of traditional machine components demonstrated molecular machines were possible: by the countless examples found in biology, it is known that sophisticated, stochastically optimized biological machines can be produced.

It is hoped that developments in nanotechnology will make possible their construction by some other means, perhaps using biomimetic principles. However, Drexler and other researchers[32] have proposed that advanced nanotechnology, although perhaps initially implemented by biomimetic means, ultimately could be based on mechanical engineering principles, namely, a manufacturing technology based on the mechanical functionality of these components (such as gears, bearings, motors, and structural members) that would enable programmable, positional assembly to atomic specification.[33] The physics and engineering performance of exemplar designs were analyzed in Drexler's book Nanosystems.

In general it is very difficult to assemble devices on the atomic scale, as one has to position atoms on other atoms of comparable size and stickiness. Another view, put forth by Carlo Montemagno,[34] is that future nanosystems will be hybrids of silicon technology and biological molecular machines. Richard Smalley argued that mechanosynthesis are impossible due to the difficulties in mechanically manipulating individual molecules.

This led to an exchange of letters in the ACS publication Chemical & Engineering News in 2003.[35] Though biology clearly demonstrates that molecular machine systems are possible, non-biological molecular machines are today only in their infancy. Leaders in research on non-biological molecular machines are Dr. Alex Zettl and his colleagues at Lawrence Berkeley Laboratories and UC Berkeley.[1] They have constructed at least three distinct molecular devices whose motion is controlled from the desktop with changing voltage: a nanotube nanomotor, a molecular actuator,[36] and a nanoelectromechanical relaxation oscillator.[37] See nanotube nanomotor for more examples.

An experiment indicating that positional molecular assembly is possible was performed by Ho and Lee at Cornell University in 1999. They used a scanning tunneling microscope to move an individual carbon monoxide molecule (CO) to an individual iron atom (Fe) sitting on a flat silver crystal, and chemically bound the CO to the Fe by applying a voltage.

The nanomaterials field includes subfields which develop or study materials having unique properties arising from their nanoscale dimensions.[40]

These seek to arrange smaller components into more complex assemblies.

These seek to create smaller devices by using larger ones to direct their assembly.

These seek to develop components of a desired functionality without regard to how they might be assembled.

These subfields seek to anticipate what inventions nanotechnology might yield, or attempt to propose an agenda along which inquiry might progress. These often take a big-picture view of nanotechnology, with more emphasis on its societal implications than the details of how such inventions could actually be created.

Nanomaterials can be classified in 0D, 1D, 2D and 3D nanomaterials. The dimensionality play a major role in determining the characteristic of nanomaterials including physical, chemical and biological characteristics. With the decrease in dimensionality, an increase in surface-to-volume ratio is observed. This indicate that smaller dimensional nanomaterials have higher surface area compared to 3D nanomaterials. Recently, two dimensional (2D) nanomaterials are extensively investigated for electronic, biomedical, drug delivery and biosensor applications.

There are several important modern developments. The atomic force microscope (AFM) and the Scanning Tunneling Microscope (STM) are two early versions of scanning probes that launched nanotechnology. There are other types of scanning probe microscopy. Although conceptually similar to the scanning confocal microscope developed by Marvin Minsky in 1961 and the scanning acoustic microscope (SAM) developed by Calvin Quate and coworkers in the 1970s, newer scanning probe microscopes have much higher resolution, since they are not limited by the wavelength of sound or light.

The tip of a scanning probe can also be used to manipulate nanostructures (a process called positional assembly). Feature-oriented scanning methodology may be a promising way to implement these nanomanipulations in automatic mode.[57][58] However, this is still a slow process because of low scanning velocity of the microscope.

Various techniques of nanolithography such as optical lithography, X-ray lithography, dip pen nanolithography, electron beam lithography or nanoimprint lithography were also developed. Lithography is a top-down fabrication technique where a bulk material is reduced in size to nanoscale pattern.

Another group of nanotechnological techniques include those used for fabrication of nanotubes and nanowires, those used in semiconductor fabrication such as deep ultraviolet lithography, electron beam lithography, focused ion beam machining, nanoimprint lithography, atomic layer deposition, and molecular vapor deposition, and further including molecular self-assembly techniques such as those employing di-block copolymers. The precursors of these techniques preceded the nanotech era, and are extensions in the development of scientific advancements rather than techniques which were devised with the sole purpose of creating nanotechnology and which were results of nanotechnology research.[59]

The top-down approach anticipates nanodevices that must be built piece by piece in stages, much as manufactured items are made. Scanning probe microscopy is an important technique both for characterization and synthesis of nanomaterials. Atomic force microscopes and scanning tunneling microscopes can be used to look at surfaces and to move atoms around. By designing different tips for these microscopes, they can be used for carving out structures on surfaces and to help guide self-assembling structures. By using, for example, feature-oriented scanning approach, atoms or molecules can be moved around on a surface with scanning probe microscopy techniques.[57][58] At present, it is expensive and time-consuming for mass production but very suitable for laboratory experimentation.

In contrast, bottom-up techniques build or grow larger structures atom by atom or molecule by molecule. These techniques include chemical synthesis, self-assembly and positional assembly. Dual polarisation interferometry is one tool suitable for characterisation of self assembled thin films. Another variation of the bottom-up approach is molecular beam epitaxy or MBE. Researchers at Bell Telephone Laboratories like John R. Arthur. Alfred Y. Cho, and Art C. Gossard developed and implemented MBE as a research tool in the late 1960s and 1970s. Samples made by MBE were key to the discovery of the fractional quantum Hall effect for which the 1998 Nobel Prize in Physics was awarded. MBE allows scientists to lay down atomically precise layers of atoms and, in the process, build up complex structures. Important for research on semiconductors, MBE is also widely used to make samples and devices for the newly emerging field of spintronics.

However, new therapeutic products, based on responsive nanomaterials, such as the ultradeformable, stress-sensitive Transfersome vesicles, are under development and already approved for human use in some countries.[60]

Because of the variety of potential applications (including industrial and military), governments have invested billions of dollars in nanotechnology research. Prior to 2012, the USA invested $3.7 billion using its National Nanotechnology Initiative, the European Union invested $1.2 billion, and Japan invested $750 million.[61] Over sixty countries created nanotechnology research and development (R&D) programs between 2001 and 2004. In 2012, the US and EU each invested $2.1 billion on nanotechnology research, followed by Japan with $1.2 billion. Global investment reached $7.9 billion in 2012. Government funding was exceeded by corporate R&D spending on nanotechnology research, which was $10 billion in 2012. The largest corporate R&D spenders were from the US, Japan and Germany which accounted for a combined $7.1 billion.[25]

As of August 21, 2008, the Project on Emerging Nanotechnologies estimates that over 800 manufacturer-identified nanotech products are publicly available, with new ones hitting the market at a pace of 34 per week.[20] The project lists all of the products in a publicly accessible online database. Most applications are limited to the use of "first generation" passive nanomaterials which includes titanium dioxide in sunscreen, cosmetics, surface coatings,[62] and some food products; Carbon allotropes used to produce gecko tape; silver in food packaging, clothing, disinfectants and household appliances; zinc oxide in sunscreens and cosmetics, surface coatings, paints and outdoor furniture varnishes; and cerium oxide as a fuel catalyst.[19]

Further applications allow tennis balls to last longer, golf balls to fly straighter, and even bowling balls to become more durable and have a harder surface. Trousers and socks have been infused with nanotechnology so that they will last longer and keep people cool in the summer. Bandages are being infused with silver nanoparticles to heal cuts faster.[63] Video game consoles and personal computers may become cheaper, faster, and contain more memory thanks to nanotechnology.[64] Also, to build structures for on chip computing with light, for example on chip optical quantum information processing, and picosecond transmission of information.[65]

Nanotechnology may have the ability to make existing medical applications cheaper and easier to use in places like the general practitioner's office and at home.[66] Cars are being manufactured with nanomaterials so they may need fewer metals and less fuel to operate in the future.[67]

Scientists are now turning to nanotechnology in an attempt to develop diesel engines with cleaner exhaust fumes. Platinum is currently used as the diesel engine catalyst in these engines. The catalyst is what cleans the exhaust fume particles. First a reduction catalyst is employed to take nitrogen atoms from NOx molecules in order to free oxygen. Next the oxidation catalyst oxidizes the hydrocarbons and carbon monoxide to form carbon dioxide and water.[68] Platinum is used in both the reduction and the oxidation catalysts.[69] Using platinum though, is inefficient in that it is expensive and unsustainable. Danish company InnovationsFonden invested DKK 15 million in a search for new catalyst substitutes using nanotechnology. The goal of the project, launched in the autumn of 2014, is to maximize surface area and minimize the amount of material required. Objects tend to minimize their surface energy; two drops of water, for example, will join to form one drop and decrease surface area. If the catalyst's surface area that is exposed to the exhaust fumes is maximized, efficiency of the catalyst is maximized. The team working on this project aims to create nanoparticles that will not merge. Every time the surface is optimized, material is saved. Thus, creating these nanoparticles will increase the effectiveness of the resulting diesel engine catalystin turn leading to cleaner exhaust fumesand will decrease cost. If successful, the team hopes to reduce platinum use by 25%.[70]

Nanotechnology also has a prominent role in the fast developing field of Tissue Engineering. When designing scaffolds, researchers attempt to mimic the nanoscale features of a cell's microenvironment to direct its differentiation down a suitable lineage.[71] For example, when creating scaffolds to support the growth of bone, researchers may mimic osteoclast resorption pits.[72]

Researchers have successfully used DNA origami-based nanobots capable of carrying out logic functions to achieve targeted drug delivery in cockroaches. It is said that the computational power of these nanobots can be scaled up to that of a Commodore 64.[73]

Commercial nanoelectronic semiconductor device fabrication began in the 2010s. In 2013, SK Hynix began commercial mass-production of a 16nm process,[74] TSMC began production of a 16nm FinFET process,[75] and Samsung Electronics began production of a 10nm process.[76] TSMC began production of a 7nm process in 2017,[77] and Samsung began production of a 5nm process in 2018.[78] In 2019, Samsung announced plans for the commercial production of a 3nm GAAFET process by 2021.[79]

Commercial production of nanoelectronic semiconductor memory also began in the 2010s. In 2013, SK Hynix began mass-production of 16nm NAND flash memory,[74] and Samsung began production of 10nm multi-level cell (MLC) NAND flash memory.[76] In 2017, TSMC began production of SRAM memory using a 7nm process.[77]

An area of concern is the effect that industrial-scale manufacturing and use of nanomaterials would have on human health and the environment, as suggested by nanotoxicology research. For these reasons, some groups advocate that nanotechnology be regulated by governments. Others counter that overregulation would stifle scientific research and the development of beneficial innovations. Public health research agencies, such as the National Institute for Occupational Safety and Health are actively conducting research on potential health effects stemming from exposures to nanoparticles.[80][81]

Some nanoparticle products may have unintended consequences. Researchers have discovered that bacteriostatic silver nanoparticles used in socks to reduce foot odor are being released in the wash.[82] These particles are then flushed into the waste water stream and may destroy bacteria which are critical components of natural ecosystems, farms, and waste treatment processes.[83]

Public deliberations on risk perception in the US and UK carried out by the Center for Nanotechnology in Society found that participants were more positive about nanotechnologies for energy applications than for health applications, with health applications raising moral and ethical dilemmas such as cost and availability.[84]

Experts, including director of the Woodrow Wilson Center's Project on Emerging Nanotechnologies David Rejeski, have testified[85] that successful commercialization depends on adequate oversight, risk research strategy, and public engagement. Berkeley, California is currently the only city in the United States to regulate nanotechnology;[86] Cambridge, Massachusetts in 2008 considered enacting a similar law,[87] but ultimately rejected it.[88]

Nanofibers are used in several areas and in different products, in everything from aircraft wings to tennis rackets. Inhaling airborne nanoparticles and nanofibers may lead to a number of pulmonary diseases, e.g. fibrosis.[89] Researchers have found that when rats breathed in nanoparticles, the particles settled in the brain and lungs, which led to significant increases in biomarkers for inflammation and stress response[90] and that nanoparticles induce skin aging through oxidative stress in hairless mice.[91][92]

A two-year study at UCLA's School of Public Health found lab mice consuming nano-titanium dioxide showed DNA and chromosome damage to a degree "linked to all the big killers of man, namely cancer, heart disease, neurological disease and aging".[93]

A Nature Nanotechnology study suggests some forms of carbon nanotubes a poster child for the "nanotechnology revolution" could be as harmful as asbestos if inhaled in sufficient quantities. Anthony Seaton of the Institute of Occupational Medicine in Edinburgh, Scotland, who contributed to the article on carbon nanotubes said "We know that some of them probably have the potential to cause mesothelioma. So those sorts of materials need to be handled very carefully."[94] In the absence of specific regulation forthcoming from governments, Paull and Lyons (2008) have called for an exclusion of engineered nanoparticles in food.[95] A newspaper article reports that workers in a paint factory developed serious lung disease and nanoparticles were found in their lungs.[96][97][98][99]

Calls for tighter regulation of nanotechnology have occurred alongside a growing debate related to the human health and safety risks of nanotechnology.[100] There is significant debate about who is responsible for the regulation of nanotechnology. Some regulatory agencies currently cover some nanotechnology products and processes (to varying degrees) by "bolting on" nanotechnology to existing regulations there are clear gaps in these regimes.[101] Davies (2008) has proposed a regulatory road map describing steps to deal with these shortcomings.[102]

Stakeholders concerned by the lack of a regulatory framework to assess and control risks associated with the release of nanoparticles and nanotubes have drawn parallels with bovine spongiform encephalopathy ("mad cow" disease), thalidomide, genetically modified food,[103] nuclear energy, reproductive technologies, biotechnology, and asbestosis. Dr. Andrew Maynard, chief science advisor to the Woodrow Wilson Center's Project on Emerging Nanotechnologies, concludes that there is insufficient funding for human health and safety research, and as a result there is currently limited understanding of the human health and safety risks associated with nanotechnology.[104] As a result, some academics have called for stricter application of the precautionary principle, with delayed marketing approval, enhanced labelling and additional safety data development requirements in relation to certain forms of nanotechnology.[105]

The Royal Society report[17] identified a risk of nanoparticles or nanotubes being released during disposal, destruction and recycling, and recommended that "manufacturers of products that fall under extended producer responsibility regimes such as end-of-life regulations publish procedures outlining how these materials will be managed to minimize possible human and environmental exposure" (p. xiii).

The Center for Nanotechnology in Society has found that people respond to nanotechnologies differently, depending on application with participants in public deliberations more positive about nanotechnologies for energy than health applications suggesting that any public calls for nano regulations may differ by technology sector.[84]

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