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Nanotechnology Tutorial

Nanotechnology Tutorial Foundations

This introductory chapter defines nanoscience, nanotechnologies and nanomaterials. It illustrates in general terms what is ‘special’ about the ‘nano-world’ and why this new area of science and technology is exciting and worth bringing into the classroom.

Definition of nanoscience and nanotechnologies

The most common working definition of nanoscience is:

‘Nanoscience is the study of phenomena and manipulation of materials at atomic, molecular and macromolecular scales, where properties differ significantly from those at a larger scale’.

Bulk materials (the ‘big’ pieces of materials we see around us) possess continuous (macroscopic) physical properties. The same applies to micron-sized materials (e.g. a grain of sand). But when particles assume nanoscale dimensions, the principles of classic physics are no longer capable of describing their behavior (movement, energy, etc.): at these dimensions, the principles of quantum mechanics principles. The same material (e.g. gold) at the nanoscale can have properties (e.g. optical, mechanical and electrical) which are very different from (and even opposite to!) the properties the material has at the macroscale (bulk). Nanotechnologies are defined thus:

‘Nanotechnologies are the design, characterization, production and application of structures, devices and systems by controlling shape and size at the nanometre scale.’

In the next sections of this chapter we will discuss these definitions and their meaning, starting with what is meant by the ‘nanometre scale’.

The nanometre scale

The nanometre scale is conventionally defined as 1 to 100 nm. One nanometre is one-billionth of a metre (10-9 m). The size range is normally set to a minimum of 1 nm to avoid single atoms or very small groups of atoms being designated as nano-objects (Figure 1). Therefore, nanoscience and nanotechnologies deal with clusters of atoms of 1 nm in at least one dimension.

What is a nanomaterial?

A nanomaterial is an object that has at least one dimension in the nanometre scale (approximately 1 to 100 nm). Nanomaterials are categorized according to their dimensions as shown in Table 1.
A very important concept to bring in to the classroom is ‘the smallness of nano’. Nanomaterials are larger than single atoms but smaller than bacteria and cells. It is useful to use a scale such as the one shown in Figure 2where students can visualize the relationship between bulk materials, for example, a tennis ball, and nanomaterials.

What makes ‘nano’ special

Nano’ means small, very small; But why is this special? There are various reasons why nanoscience and nanotechnologies are so promising in materials, engineering and related sciences. First, at the nanometre scale, the properties of matter, such as energy, change. This is a direct consequence of the small size of nanomaterials, physically explained as quantum effects. The consequence is that material (e.g. a metal) when in a nano-sized form can assume properties that are very different from those when the same material is in a bulk form. For instance, bulk silver is non-toxic, whereas silver nanoparticles are capable of killing viruses upon contact. Properties like electrical conductivity, color, strength and weight change when the nanoscale level is reached: the same metal can become a semiconductor or an insulator at the nanoscale level. The second exceptional property of nanomaterials is that they can be fabricated atom by atom by a process called bottom-up. The information for this fabrication process is embedded in the material building blocks so that these can self-assemble in the final product. These two fabrication methods are reviewed in Module 1, Chapter 7: Fabrication methods. Finally, nanomaterials have an increased surface-to-volume ratio compared to bulk materials. This has important consequences for all those processes that occur at the surface of a material, such as a catalysis and detection. The properties that make nanomaterials ‘special’ are further discussed in Module 1, Chapter 4: Fundamental ‘nano-effects’.

From nanoscience to nanotechnologies

From nanoscience to nanotechnologies Nanoscience is an ‘interdisciplinary science’, which means that it involves concepts of more than one discipline, such as chemistry, physics, etc. There are other disciplines that are inherently interdisciplinary, such as materials science (and engineering), which cover, at the same time, concepts of chemistry and physics. Nanoscience further expands the borders of material science by adding biology and biochemistry to the mix. Nanoscience is thus a ‘horizontal-integrating interdisciplinary science that cuts across all vertical sciences and engineering disciplines’ (Figure 3).
The application of nanoscience to ‘practical’ devices is called nanotechnologies. Nanotechnologies are based on the manipulation, control and integration of atoms and molecules to form materials, structures, components, devices and systems at the nanoscale. Nanotechnologies are the application of nanoscience, especially to industrial and commercial objectives. All industrial sectors rely on materials and devices made of atoms and molecules thus, in principle, all materials can be improved with nano-materials, and all industries can benefit from nanotechnologies. In reality, as with any new technology, the ‘cost versus added benefit’ relationship will determine the industrial sectors that will mostly benefit from nanotechnologies.
Thus, nanotechnologies are horizontal-enabling convergent technologies (Figure 4). They are ‘horizontal’ because they cut across numerous industrial sectors; they are ‘enabling’ since they provide the platform, the tools to realize certain products; and are ‘convergent’ because they bring together sectors of science that were previously separated.
One example is DNA silicon chips, which are an example of convergence between semiconductor science (inorganic chemistry) and biology, with applications in the medical industry.

Is it nanotechnology or nanotechnologies?

When the term was first used in 1959, it was used in the singular, ‘nanotechnology’. In the last few years, the field has evolved steadily in terms of science and technology development. Scientists have also started to address the safety, ethical and societal impact of ‘nanotechnology’. In doing so, it has become clear that this is not one technology, but that different nanotechnologies exist (which all share the common concept of using the properties of matter at the nanoscale). There has even been a call from a prominent scientist and expert in nanotechnologies to stop using the singular, and to use the plural, precisely to communicate the variety of materials and methods involved in nanotechnologies. Nowadays, the plural form is most used and it is the form that will be used in this Teachers Training Kit.
Bringing ‘nano’ into the classroom:
Why and how?
There are numerous reports that emphasize the need to ‘revitalize’ science teaching in school, particularly at the high school (14+) level. It is also oſten recommended in those reports that inquiry-based science education (or problem-based learning) is encouraged, where teaching is conducted through an inductive (rather than deductive) method. This should be combined with numerous ‘hands-on’ activities to allow students to see science for themselves, and then learn and understand the theoretical explanation of what they see. Nanoscience and nanotechnologies offer such opportunities!

A cutting-edge science and technology

Nanoscience and nanotechnologies offer teachers a new instrument to bring exciting science and technology into the classroom. Nanotechnologies are now used in numerous devices with which young students are very familiar, such as computers, mobile phones and iPods. Nanoscience offers the possibility to improve numerous material properties and create new ones; in the future, we will have more and more products that incorporate some form of ‘nano’ either a nanomaterial or a nano-enabled technology. Bringing ‘nano’ into the classroom means bringing in the latest cutting-edge science and technology and talking about very exciting future scientific developments.

Hands-on nano!

One of the peculiarities of nanoscience is that numerous ‘nano-effects’ can be seen in our ‘macro world’. The best example is a gold colloid (gold nanoparticles of about 15 nm dispersed in water) which is red in color. When some salt solution is added to the gold colloid, it turns blue! There are many ‘hands-on’ activities and demonstrations that can be used to show the properties of nanomaterials — effects that are visible! So even though the ‘nano-world’ is invisible, we can appreciate its effects in materials with which youngsters are very familiar, such as gold. In this Teachers Training Kit, these activities are described in an Experiment Module and throughout the main text as simple demonstrations that a teacher can perform in the classroom.

‘Nano’ in the context of ‘conventional’ scientific disciplines

One of the challenges a science teacher might face is how to insert nanoscience into conventional science curricula. Where does this ‘new’ science fit into the ‘conventional’ scientific disciplines chemistry, physics or biology? The aim of this training kit is also to provide teachers with practical ideas on how to integrate nanoscience and nanotechnologies into their science curriculum.

So the question is: If it’s not all new, why is it so special? In recent years, researchers have been able to uncover the enormous potential of nanoscience and nanotechnologies thanks to a new set of analytical and fabrication tools. At the same time, in recent years, new nanomaterials have been intentionally fabricated or discovered, novel nanotools have been developed and old ones implemented, and novel properties of matter at the nanoscale level have been discovered.

So the question is: If it’s not all new, why is it so special? In recent years, researchers have been able to uncover the enormous potential of nanoscience and nanotechnologies thanks to a new set of analytical and fabrication tools. At the same time, in recent years, new nanomaterials have been intentionally fabricated or discovered, novel nanotools have been developed and old ones implemented, and novel properties of matter at the nanoscale level have been discovered.

All of this has allowed the systematic investigation of nanomaterials and the realization that the exceptional properties of matter at the nanoscale level can be used to build new materials, systems and devices with properties, capabilities and functions that could not be achieved if bulk materials were used. This is where the novelty lies, and the reason for being excited about it! The exceptional properties of matter at the nanoscale have prompted scientists to ‘reinvent’ the way materials are engineered and produced and are opening up exciting new opportunities in many different fields.

Nanoscience is thus a ‘work-in-progress science’. A ‘work’ that finds its roots in disciplines, such as chemistry and physics, where much fundamental knowledge is well established, and that is progressing towards fields where new knowledge is currently being created and collected.
For these reasons, we prefer to describe nanoscience as an evolution of more traditional scientific disciplines. ‘Nano’ is not a revolution per se, but nanotechnologies might have some revolutionary implications for our society in terms of the applications or tools that they will enable.

Nanoscience in nature: a great starting point

Even though nanoscience is oſten perceived as a science of the future, it is actually the basis for all systems in our living and mineral world. We see hundreds of examples of nanoscience right in front of our eyes every day — from geckos that can walk upside down on a ceiling, apparently against gravity, to butterflies with iridescent colours, to fireflies that glow at night. In nature, we encounter some outstanding solutions to complex problems in the form of fine nanostructures with which precise functions are associated. In recent years, researchers have had access to new analytical tools to see and study those structures and related functions in depth. This has further stimulated research in the nanoscience area and has catalyzed nanotechnologies. So, in a sense, natural nanoscience is the basis and inspiration for nanotechnologies.

Natural nanomaterials offer a great starting point to bring nanoscience into the classroom. Images from microscopes are a great resource, especially if used consequently in a ‘zoom-in’ fashion, starting from a macro object (e.g. a plant leaf) and showing how zooming in with subsequent magnifications reveals finer and finer structures. This becomes extremely effective if we start with familiar, natural objects such as plants (Figure 5) and animals. Students will be fascinated to discover how many natural nanomaterials are around us.

Teaching challenges

The definition of nanoscience naturally calls for the definition of a nanometre, which is a billionth of a meter. Although the are many examples that one can present of objects that have dimensions at this level, such as the width of DNA (2 nm), mental visualization of these objects is impossible, and many studies have reported how young people, especially children, lack the mental capacity to actually imagine something this small because of lack of experience. Even for adults, mental visualization of objects with sub-micron dimensions is extremely difficult (a result of the inherent resolution of our visual ability, which is 2 µm).

However, as much as we can ask students to imagine something that is a thousand times smaller than their hair, we need to ask if they can really understand the sense of the dimensionality we are talking about. And, more importantly, if they can understand the difference between objects that are at the nanoscale level and objects that are even smaller, such as atoms. For some people, knowing that a rock is a million years old or a thousand million years old makes no difference: both dimensions are just ‘huge’ and are confused in a ‘time blur’. Similarly, the nanoscale and the atomic scale can be perceived as a ‘scale blur’, just too small to think of. Therefore, the challenge here is to introduce the nanoscale and the concept of nanoscience in a meaningful way, one that grasps the attention of the students but that also means something to them. In this sense, an inquiry-based approach (based on student questions) together with hands-on activities can help. For example, starting from a cube of a soſt material and cutting it progressively until it can no longer be handled (which will not lead to a nanometre-sized cube, but will give a sense of smallness); or using ratio examples, such as how tall would a tower of a single paper of sheets be, assuming each sheet is 1 nm. Images from microscopes are probably one of the best resources we have, especially if used consequently in a ‘zoom-in’ fashion, as described in the previous section. But, what is also important is showing the peculiarity of the nano-meter scale, why objects at this level are ‘special’ and behave differently from their bulk counterparts. Examples should be given so that instead of trying to imagine a nanometre, students perceive what it means, for example, for a certain material to be 2 nm rather than 2 mm. Gold is a prime cause, and the classic example is a gold wedding ring compared with multicolored gold quantum dots (colloidal gold). Whatever the example or the methodology chosen to communicate, it is important to remember that young people will have great difficulty in conceiving nanoscale objects; so it is important not to ask them to visualize how small a nanometre is but rather that they appreciate what it means to be so small. NANOYOU has developed numerous tools (a memory game, puzzles and laboratory exercises) precisely to overcome those difficulties.

One aspect that is oſten overlooked (or assumed) when introducing nanoscience and nanotechnology is the actual nature of a ‘nano-object’ or ‘nanomaterial’. It is possible to mistakenly give the impression to the audience that these are free-standing objects or that these are aerosol-like particles that can float in a medium. Although some nanoparticles are airborne, most of the nanomaterials under research or used in commercial products are integrated or attached to another substrate. Furthermore, nanoscience does not just deal with nano-objects but also nanostructures within larger objects. For instance, a wire having the dimension of a hair (say, 2 µm) can be formed of molecules which are orderly arranged in nanowires.

Talking about the ‘bigger picture’

nanotechnologies have progressed at a fast pace in the last few years, both in laboratories and in the commercialization of numerous products. The promise of nanotechnologies is great in many applications and this has resulted in conspicuous investments both at the research level and in industry. Other emerging technologies in the past were presented to the scientific community (and industry) as revolutionary, with enormous potential for commercialization, most notably the genetic engineering of foodstuffs. Genetically modified organisms were expected to bring profit and advancement in the food and medical industries. Due to a number of issues (one of the most important being very poor communication between the scientific community and the popular media), GMOs were not received favorably by the consumer community, and the result has actually been the opposite. In many countries, these products have been banned or strongly regulated. Numerous ethical questions were also raised on ‘who’ would benefit from these products, and what implications they might have for people’s long-term health, as well as the life cycle of animals and plants. The GMO case is a clear example of an emerging technology that did not go through a careful Ethical, Legal and Social Aspects (ELSA) analysis. It is also a clear example of an innovative technology that suffered a backlash from consumers to the point where the research was stopped and entire research centers were closed. Consumers had a power that scientists (and even the media) did not realize until it was too late.

With nanotechnologies, there is a general determination to ‘do it differently’ at all levels. Probably for the first time in the history of scientific innovation, researchers, regulators, non-governmental organizations (NGOs), consumer organizations, trade unions and industry are all involved in setting guidelines, action plans, protocols, codes of conduct, regulations, etc, to make sure that nanotechnologies realize their potentials while protecting the safety of consumers and the environment (in terms of pollution and impact on its life cycles), and are ethically sound. Clearly, this is a massive effort and the work is complex and has only started. Throughout this Teachers Training Kit, we will indicate areas of nanotechnology applications that are raising ELSA issues, and the actions that are currently being taken to address them.

For the teacher, bringing ELSA issues into the classroom is an opportunity to talk about science, technology and innovation in a more complex, ‘three-dimensional’ fashion. It gives educators an opportunity to stimulate discussions in class about which innovations students think are valuable (and which are not), who will benefit from these, at what cost, etc. It is a chance to think and talk about the ‘bigger picture’ of science and innovation and think about its implications not just for the single individual, but for society.

Talking about ELSA and safety in the classroom

Questions of ethics, social impact, safety, etc., are rarely part of a secondary science curriculum. Depending on age and school curricula, some students might have undertaken some philosophy courses, others probably not: therefore, ELSA issues are probably a new concept for most. The question is then how to introduce those concepts without overloading pupils with information, and how to respond adequately to questions raised in class. Otherwise, the result might be a feeling that ELSA and safety questions are just too big to be even analyzed.

The aim of NANOYOU is also to provide teachers with resources to encourage class discussion about ELSA topics related to nanotechnologies. To focus the discussion, teachers have access to a number

In the next section, we provide an overview of ELSA topics that relate to nanotechnologies and an overview of the safety of nanomaterials. In each section, the relevant NANOYOU tools that have been developed to promote dialogue in class are highlighted.

When discussing ELSA and safety topics, it is useful to encourage students to reflect on other innovative technologies that they are familiar with and that have had important ELSA and safety implications. Some examples are provided in Appendix A.

Overview of ELSA issues in nanotechnologies

What follows is a short overview of crucial ELSA questions that are relevant to nanotechnologies. The list is not exhaustive and aims to give teachers an idea of the vastness and complexity of these issues. Most are open questions for which we don’t provide answers they are meant to spur debates in class with students.

Privacy

We live in a world where our movement is oſten controlled by hidden cameras. Miniaturization has allowed these devices to be integrated into many objects, and nanotechnologies will most likely lead to even smaller devices allowing them to be integrated into textiles and other composite materials. Nowadays, consumer choices are tracked by Internet purchases and other indirect means, but ‘smart’ labels currently under development use a built-in tracking system called Radio Frequency Identification (RFID). These labels do already exist, but are fairly large, for instance, in e-passports (see Module 2, Chapter 4: Information and Communication Technologies for more information). The vision in the future is to miniaturize them to a point that every commercial object will contain a ‘smart’ label, and be able to communicate its position. This would ensure, for example, in the case of food packages, product integrity, transport conditions, etc. RFID technology could be the ultimate solution to theſt and fraud. Opponents warn that such devices could be used as ‘psychics’, even integrated into humans, and which could be used by governments, leading to an increased loss of civil liberties. If, for instance, food companies were to use this type of chip on the products we consume, they would have access to an incredible amount of private information.

Another vision of the ICT industry is the concept of ambient intelligence: computation and communication always available and ready to serve the user in an intelligent way (i.e. satisfying certain requirements). The vision is to have electronic devices that work as a gateway between the user and the environment. This will require ubiquitous sensing and computing: devices must be highly miniaturized, integrated in the environment, in soſt materials like textiles, autonomous, robust, and require low power consumption. Nanotechnologies have the conceptual capacity to realize this vision. The time frame from ‘vision’ to reality could be decades but, if this was to come true, we would live in a world.

Justice

Who should benefit from nanotechnologies? Are nanotechnologies going to further increase the economic and social divide between ‘north’ and ‘south’ in the world? This is referred to as the ‘nano divide’.Will medical diagnostic devices, or therapies, developed with nanotechnologies, be available for anyone, and distributed through the public health system, or will they be so expensive that only a limited sector of the population will have access to them?

The questions of justice related to nanotechnologies are not unique, but rather relevant to many technological advancements. The history of drug development, and the associate generation of patents behind commercialized drugs, is definitely filled with questions of justice. Nanotechnologies are enabling technologies with applications in many sectors, which promise to improve the quality of life of individuals in numerous ways. For this reason, the questions of justice are even more important and vast.

Early diagnostics

Diagnostic nanosensors allow the early detection of various diseases, such as cancer, at the very onset of the symptoms, before the disease is perceived by the patient (see Module 2, Chapter 1: Medicine and healthcare. Early detection means a higher chance of successfully treating and overcoming the disease. On the other hand, some worry that this will give doctors access to a large amount of personal information. The question is: Where is this information going to be stored, and who will have access to it? Furthermore, what if those devices are used not as a diagnostic tool but as a means to assess a person’s medical condition by other entities, such as insurance companies or job agencies? Clearly, these devices open questions of privacy data use and possible misuse.

Some early diagnostic devices already exist, such as genetic screening devices. Nanotechnology is directly involved in the development of more powerful and precise genetic screening devices, which, at present, are only available for a small range of common diseases and are fairly imprecise. In genetic screening, the doctor gathers information on the genetic predisposition a patient has to a certain disease. Scientists already know that the evolution of a disease does not only depend on genetic predisposition but also on the diet followed by the patient, the lifestyle and the environment in which they live. So the question is: Does having a predisposition to disease makes a person ‘ill’? When does ‘illness’ start? And even more: Do we want to know this kind of information?

More than ‘human’?

Humans have always tried to improve their health status and lifestyle: nowadays, there are numerous drugs and medical technologies that can treat conditions that only a few decades ago were deadly. But, medical advancements have not just been limited to the treatment of disease: the reconstruction of injured body parts is now possible though innovative biomaterials and implants, and tissue engineering is opening up the possibility to recreate organs from cultures of stem cells. Nanotechnologies are already playing an important part in modern medical diagnosis and treatment technologies, and are opening new avenues for future developments.

Many technologies we have today allow doctors to restore a loss sustained as a consequence of an injury or a congenital condition (e.g. vision or hearing impairment). Some would argue that this is already ‘unnatural’, in the sense that it gives humans a capacity that they would not otherwise have. If you think about it, even glasses provide people who have poor vision a capacity they would not have naturally. Today, we also have access to treatments that alter our natural appearance through plastic surgery. In the future, researchers think it might be possible to create implants that allow humans to have additional skills, such as being able to see in the dark or have implants that can improve human brain capacities. Neuroprosthetics are another example. Bioengineers and medical engineers say that their role should be to compensate for a body’s deficit (as a result of an accident or a disease), not to replace any existing function. It should not lead to the enhancement of human capabilities. Nevertheless, nanotechnologies are making these developments more feasible and affordable, obliging researchers in the field, as well as regulators, ethicists and sociologists to reflect on the social, medical and ethical consequences of these devices (see Module 2, Chapter 1: Medicine and healthcare).

Nanotechnologies are involved in those medical advancements, as are genetic engineering and biotechnology. So the question becomes: Are these developments leading to treatments that surpass being ‘human’?

Nanotechnologies in consumer products

In 2006, the Project on Emerging Nanotechnology (Woodrow Wilson International Center for Scholars) started compiling a nanotechnology consumer product inventory with the intention of collecting, archiving and sharing information on consumer products which producers claim to be nano. About 200 products were identified in March 2006: aſter little more than one year, this number had more than doubled. At the time of writing (August 2010), the inventory has more than 1 100 products listed.

Products in this inventory are categorized on their (explicit) application, specifically: Appliances; Automotive; Goods for Children; Electronics and Computers; Food and Beverages; Health and Fitness; Home and Garden. Although the project aims at identifying true nano products, the inventory curators clearly state ‘we have made no attempt to verify manufacturers’ claims about the use of nanotechnology in these products, nor have we conducted any independent testing of the products’. Therefore, the inventory contains products that claim to be enabled by nanotechnologies, but this is not checked nor demonstrated. For this reason, one should be cautious when looking at this list, and should also remember the following.

1. There are a large number of nano characteristics that could be included in a consumer product, such as a coating (thin coatings and layers in the nanometre range, either applied to the material or formed on use) or a nanomaterial (e.g. nanotubes, nanoparticles). Furthermore, nanotechnology could be used to produce the consumable without being responsible for its final characteristics: in this case, nanotechnology is only the enabling technology for production.

2. Technical, detailed information regarding these consumer products is oſten limited due to corporate secrecy.

To date, the majority of products listed belong to the ‘Health and Fitness’ group, among which cosmetics and textiles represent the majority of products.

Among the materials claimed to be responsible for the nano label, silver is the most common material mentioned, followed by carbon (which includes fullerenes), zinc (including zinc oxide), silica, titanium (including titanium dioxide) and gold.

Safety of nanomaterials

The safety of nanomaterials has become a crucial question in the last few years, particularly as the number of consumer products containing them has been rising every year.

The fact that nanomaterials, by definition, are materials that have a size comparable to biomolecules (e.g. proteins, DNA) raises the question of their safety. Could nanomaterials interact with biomolecules in an adverse manner, triggering a toxic effect? Could nanomaterials pass protection barriers in cells? In nanomedicine, as we will see in Module 2, Chapter 1: Medicine and healthcare, nanomaterials are used precisely to target infected cells and deliver drug agents locally. They are designed to pass through cell membranes, for instance. The question of toxicity extends also to ecotoxicity: What happens when materials containing nanoparticles reach landfills and degrade? Will nanomaterials be dispersed in the environment? In what dose? Could this cause harm to ecosystems?

It would be incorrect to say that we know nothing about the toxicological properties of nanomaterials. In the last years, a wealth of information has been collected and reported by authoritative research groups. What it is not clear is how relevant these results are for humans, since tests have so far been conducted in animal models or in vitro. Another problem is that different testing methods are used in different laboratories, making it difficult to compare results. Research so far has mainly focused on two groups of materials: carbon-based nanomaterials (carbon nanotubes and fullerenes) and metal or metal-oxide nanoparticles (e.g. ultrafine titanium dioxide, TiO2). Several studies seem to indicate that some forms of carbon nanotubes show pulmonary toxicity and that this depends on the production method and the length and surface properties of the carbon tubes. Similarly, TiO2has have been reported to cause inflammation in the lungs when inhaled in high doses.

Scientists recognise that before a full assessment of nanomaterial toxicity can proceed, some fundamental issues need to be resolved.

The need for a definition of nano materials crucial. It is not just a matter of nomenclature; it is, more importantly, a matter of defining what ‘cut size’ should be considered in nanotoxicology. It is a common belief among toxicologists that the conventional scale 1–100 nm now used to define a nanomaterial in nanotoxicology is not exhaustive, as nanomaterials oſten aggregate or agglomerate in larger particles with dimensions ranging from hundreds of nanometres to microns.

The reference materials must be defined. Scientists have reported how the same nanomaterial (e.g. nano-sized TiO2) purchased from two different manufacturers can give strikingly different toxicological results when tested. In order to define reference materials, they need to be fully characterized, which means deciding what standard measuring methods to use (or, possibly, developing new ones, if the existing ones prove inadequate).

It is important to test materials pure and free from contaminations. For instance, carbon nanotubes are commonly contaminated with iron due to their manufacturing process. Scientists report that the removal of the iron from the carbon nanotube moiety dramatically reduces the oxidant generation and the cytotoxicity (i.e. toxicity to cells) of the material. The hypothesis is that it is the nanometal oxide — rather than the carbon nanotube — that generates the reactive oxygen species 8, responsible for the toxic effect.

The medium used to disperse the nanomaterial during the toxicological testing is crucial. It has been reported how fullerenes are best dispersed in calf serum, whereas they cannot be dispersed at all in water. Lack of dispersion can lead to false results or confused toxicological results: therefore, it is essential that dispersion media are defined for each nanomaterial to be tested.

Overall, the scientific community agrees that progress has been made in the toxicological evaluation of nanomaterials. There is still much research to be done, but some key matrices have been identified — for example, that surface area is a more important parameter than mass when dealing with engineered nanoparticles, and some targets and common behaviors have been also identified. The question is now how to make a risk assessment framework from these data, how to convert scattered numbers collected in numerous laboratories around the world into a risk management strategy for the safe handling of nanomaterials.

Before risk management for nanotechnologies can be developed and implemented, a fundamental question needs to be answered: What is the real risk of nanotechnologies? Presently, nanotechnology is an umbrella term that covers a very large number of materials, applications and instrumentations. There is a need to classify nanotechnology applications and nanomaterials. This also applies to the risk debate: the starting point for this debate is to identify the real safety concerns of nanomaterials. Presently, while there is, at times, the hype in describing the benefits of nanotechnology, there is also hype in the associated risk debate. The starting point should be to identify the safety concerns that are peculiar to nanotechnologies and to identify the key safety needs in specific areas of applications. This will allow us to move from a rather uncoordinated and scattered toxicological assessment of nanomaterials to coordinated research and cooperation between different institutions. Precisely for this reason, it is now preferred to use the plural (nanotechnologies) rather than the singular (nanotechnology) in discussing these matters.

The second question to be answered is: How are engineered nanoparticles (ENPs) different from non-intentionally-made nanoparticles(also called nano pollution or ultrafine particles)? Nanopollution is already a reality in many workplaces, from the welding industries to paint shops and bakeries.

Nanoparticles are produced by aeroplane and motor vehicle exhaust emissions, erosion of man-made materials (e.g. tyres), as well as by natural erosion and volcanic activity. Humans are already exposed to nanopollutionin many ways and to different degrees. In the workplace, there are already some effective protective measures for workers exposed to ultrafine particles (filters, textiles, gloves). There is some evidence that established protective measures against ultrafine particles would also be effec-time against ENPs, should these be classified as hazardous. So the question becomes: Are ENPs new hazardous materials and, if so, do these pose a risk for humans and/or the environment? Is this risk different to ‘nano pollution’, and, if so, how and what should be done to deal with it? This is a complex question, one that will need time to be fully answered. Basically, at the moment, there is not enough data to provide an exhaustive answer and more research is needed (and being undertaken). But the risk associated with any material depends on the exposure route and dose, so research is also focusing on developing some measuring tools capable of detecting and distinguishing the presence of nanoparticles in the environment, regardless of their source.

Research into the potential toxic effects of nanomaterials is now a priority in most funding institutions and agencies, as it is clear that the success of nanotechnologies will also depend on how the issue of safety is handled.

As a priority, particular attention is given to silver, titanium dioxide and silica nanoparticles and carbon nanotubes, since it appears that these are the nanomaterials mostly used in consumer products. For more information on these nanomaterials, their properties and uses, see Module 1, Chapter 5:

APPENDIX

In this Appendix, some ideas are provided for teachers to use to encourage students to reflect on other innovative technologies with which they are familiar and that have had important ELSA and safety implications.

•Automotive transportation: cars and motor vehicles have certainly improved our lives by giving us the opportunity to move freely, save time in travel, and explore new places. However, pollution produced by fuel combustion is, in part, responsible for the global environmental issues that we facing now. In addition, transportation has mostly benefited industrialized nations: poor countries lack the infrastructure (metalled roads) in most cases, and people cannot afford these commodities. In our society, we have become extremely dependent on cars, especially for short trips, when alternative transport solutions exist but are not so convenient and easy (public transport, bicycles). In recent years, there has been a general call from health advisors and environmental organizations to reconsider the way we use cars, and to favor other means of transportation that pollute less and render us physically more active.

Synthetic plastic: about 100 years ago synthetic plastics like Nylon® where created. Plastics have revolutionized fabrication processes and enabled a massive production of affordable consumable goods. Nowadays, nearly all the tools we use and have around us are made of plastic: laptops, iPods, packages, shoes, cars, etc. Being artificial, these polymers do not degrade naturally (as opposed to the biopolymers used in biodegradable plastics). The consequence is that they pose a tremendous challenge when it comes to disposal. Indeed, plastics are one of the most important pollution agents in the water and on land. The problem of plastic toxicity is widespread and also involves humans: research is now showing that numerous chemicals used in plastics are toxic to humans and possibly carcinogenic. Nevertheless, the world as we know it would not exist without plastics.

The Internet: our society has been enormously changed with the advent of the Internet. This tool was invented to allow research centers around the world to communicate and exchange information easily. Today, the Internet is an unlimited source of information for everyone and, more recently, it has become a new form of social communication and networking. Imagine what would happen if the Internet were to shut down … This tool also plays an important role politically: bloggers in war areas are able to communicate what is really happening. Socially, the Internet is reshaping the way people communicate, some even say too much. Experts are concerned that youngsters use the Web as their primary communication channel, and that personal, face-to-face communication is progressively being lost. There are concerns that an abuse of this form of communication could deprive youngsters of personal encounters, considered essential for personality development.