Nanotechnology Tutorial

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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?

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.

Nanotechnologies in consumer products

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:

•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.