Several other common examples can be used to understand the “nano” scale. Fig. 1.2 compares different nanoscale materials. A human hair is approximately 100,000 nm wide, whereas a red blood cell is approximately 7,000 nm in diameter. Even smaller are typical viruses, which are between 45 and 200 nm in size. On the atomic scale, the length of a typical bond between carbon atoms and the spaces between atoms in a molecule are on the order of 0.12–0.15 nm [1–4].

Thus, structures of nanoscale materials (called nanostructures) are intermediate between the smallest structure that can be produced by man and the largest molecules of living systems. Humans’ abilities to control and manipulate nanostructures, therefore, facilitate exploring novel physical, biological, and chemical properties of systems that are of intermediate size between atoms and molecules, such as, nanoscale materials.

Two standard definitions exist for the term nanotechnology: one given by the International Organization for Standardization–Technical Committee (ISO–TC) and the other given by the National Nanotechnology Initiative of the US (NNI). According to the ISO–TC, “(i) Understanding and control of matter and processes at the nanoscale, typically, but not exclusively, below 100 nanometres in one or more dimensions where the onset of size-dependent phenomena usually enables novel applications; and (ii) Utilizing the properties of nanoscale materials that differ from the properties of individual atoms, molecules, and bulk matter, to create improved materials, devices, and systems that exploit these new properties.” Therefore, for a device to be considered “nanotechnological,” in addition to nanometric dimensions, it must also have unique properties associated with the nanoscale [2–5]. In contrast, as defined by the NNI, nanotechnology must fall between 1 and 100 nm in size [2]. The lower limit is defined by the size of atoms, as this branch of science must construct devices from atoms and molecules. For example, one hydrogen atom has a diameter of approximately one quarter of a nanometer (d = 0.25 nm). The upper limit was established based on our ability to modulate properties on scales up to 100 nm and observe the resulting phenomena in larger structures that be used to generate specific devices [2]. These phenomena differentiate truly nanoscale devices from those that are simply miniaturized versions of an equivalent macroscopic device. Thus, such larger-scale devices should be considered as microtechnologies [3].

Thus, nanotechnology is used to describe molecular-scale engineering systems. More specifically, this term refers to the ability to design, construct or manipulate devices, materials and functional systems on the nanometric scale [4,5].

Although a large number and variety of technologies and articles have recently been published on the topic of nanotechnology, this science has been applied and studied for a long time, albeit without knowledge of the relationship among the scale, the product and the resulting properties. In other words, man has manipulated materials at the nanometer level for a long time without understanding that the effects obtained were related to their nanoscale natures. One example is medieval glass-blowers who, using mixtures of gold nanoparticles of various sizes, produced differently colored stains for the fabrication of stained glass windows. A study by a research team at the University of Queensland [7] found that, in addition to the staining produced by gold nanoparticles, these nanoparticles also functioned as photocatalytic air purifiers: for example, when sunlight shone on the stained glass, air purification occurred. Another example is the experiment conducted by Michael Faraday (late 19th century), who synthesized gold nanoparticles [8] but did not understand their properties.

Regarding the manipulation of particles at the atomic level, scientists have investigated the nanometric world to find explanations and rationales for their theories, such as the atomic theory first proposed by Democritus in 400 BC, which was refined in 1913 by Ernest Rutherford and Niels Bohr [9]. Additionally, in 1867, James Clerk Maxwell performed an experiment known as Maxwell’s demon, confirming that the second law of thermodynamics has only one statistical certainty. Briefly, in this experiment, Maxwell used a chamber containing a gas at equilibrium that was divided into two parts by a wall containing a door. When the door was opened, only the particles with higher and lower velocities could change sides, resulting in the heating of one side of the chamber and the cooling of the other [10]. Thomson (1906) and Lewis (1916) [9] developed the theory of chemical bonds (ionic and covalent bonding) to describe the formation of molecules. From 1934 to 1938, Lise Maitner, Otto Frisch, Otto Hahn, and Fritz Strassman studied the radioactive isotopes produced by bombarding uranium with neutrons (the experiment was conducted by Enrico Fermi). Based on their results, they discovered the phenomenon of nuclear fission, which releases 200 MeV of energy. This discovery led to the development of atomic bombs and nuclear power plants [11]. Another example is the nuclear fusion that occur in the Sun, n (Fig. 1.3), in which four hydrogen atoms fuse to form a helium atom, generating all the energy we observe and feel on Earth [12].

Many scientists have confirmed their theories or answered chemical and/or physical questions by simply observing the phenomena resulting from the atomic or molecular behaviors of materials, and thus, it can be concluded that a scientific field and its foundation develop via studies and the formulations of theories, concepts and principles based on experimental observations. Thus, defining the basic concepts and principles of nanoscience and nanotechnology would be much more difficult without the theoretical knowledge of other branches of sciences. Indeed, most of the laws, concepts and principles that govern nanoscience are essentially the same ones that govern physics and chemistry. To illustrate this, we simply review the portion of the definition of nanotechnology that states that nanotechnology is a novel branch of science responsible for the study and development of materials at the atomic and molecular levels that have unique characteristics associated with the nanoscale. This concept confirms that the manipulation of atoms or molecules first requires theoretical knowledge of atomic theory and chemical bonds, as indicated previously.

Nanoscience is not only related to chemical and physical knowledge. There is also a great demand for biological knowledge. Biology and biochemistry also have much to gain from nanoscientific advances because DNA, viruses, and organelles are considered nanostructures [13]. For example, the National Aeronautics and Space Administration (NASA) has studied the development of nanoparticles containing DNA repair enzymes and ligands for the recognition of damaged cells [14].

In 1959, the American physicist Richard Feynman (Fig. 1.4), in his lecture “There’s plenty of room at the bottom” [15], introduced the first nanoscientific approach. Feynman explained that the entire area on the head of a pin (1/16 in.), if amplified 25,000 times, would have an area capable of housing all the pages of the Encyclopedia Britannica. He explained that the resolving power of the human eye (approximately 1,120 points per inch) corresponds to approximately the diameter of one of the tiny dots in the high-quality half-tone reproductions in the Encyclopedia. If this dot could be demagnified by over 25,000 times, it would have a diameter of 80 Å, which is sufficient space for 32 atoms of a common metal. In other words, Feynman explained that one such dot (1,120 of which can be seen by the human eye in 1 in. is large enough to contain approximately 1,000 atoms, and therefore, the size of each dot can be easily adjusted, as required by photoengraving. As a result, the entire contents of the Encyclopedia could fit on the head of a pin.

The term “Nanotechnology” was coined in 1974 by Norio Taniguchi of Tokyo University and used to describe the ability to create nanoscale materials. Until the term was formally defined, nanotechnology had not undergone major developments because it is a field that manipulates atoms and molecules, but no methods to observe and, thus, manipulate material in a controlled manner existed. However, since the invention of the first microscope, scientists have sought to amplify their ability to observe matter. Using a typical microscope with optical lenses, objects invisible to the naked eye and smaller than the wavelength of light can be observed. In contrast, with an electron microscope, it is possible to observe smaller particles with better definition, although individual atoms cannot be clearly distinguished. Then, in 1981, in the International Business Machines (IBM) laboratories in Zurich, Switzerland, Gerd Binning and Heinrich Rohrer developed a microscope known as the scanning tunneling microscope (STM), which won the Nobel Prize in Physics in 1986 and opened the door to nanotechnology and nanoscience. Fig. 1.5 shows the first commercially offered STM.

Briefly, this microscope is equipped with a very fine probe that very closely scans the sample, removing electrons and generating an image of the atomic topography on the sample surface. The Binnig and Rohrer’s STM gave rise to an entire family of instruments and techniques that revolutionized our ability to visualize surfaces and materials that previously could not be observed. Atomic force microscopy (AFM) is one example of a technique derived from STM that allowed visualizing materials that do not conduct electricity. Indeed, these novel microscopes permitted not only visualization but also manipulation of matter on the nanoscale.

One example of such manipulation is the experiment conducted by Donald M. Eigler and Erhard Schweinzer in 1989 at IBM. In their work, they manipulated 35 xenon atoms on a nickel substrate to spell out the company’s initials [18] (Fig. 1.6).

Based on this experiment, many other researchers demonstrated the possibility of manipulating matter on the nanoscale. For example, researchers at the Brazilian Agricultural Research Corporation (EMBRAPA), in the Agricultural Instrumentation division, developed a method for the nanomanipulation of a compact disk’s (CD’s) polycarbonate surface involving mechanical modification via nanolithography using a phosphorus-doped silicon tip. They used this method to “draw” the EMBRAPA symbol and the Brazilian flag on the polycarbonate substrate in a controlled manner in an area of 10 μm × 10 μm [19] (Fig. 1.7).

More recently, in 2009, researchers at Stanford University led by Hari Manoharan wrote the initials of Stanford University (SU) in letters smaller than atoms by encoding 35 bits of information per electron [20] (Fig. 1.8).

Given these advances in atomic-scale microscopy, interest in nanoscience and nanotechnology has been steadily growing. According to Whitesides [13], there are six reasons to study nanoscience:

The word nanotechnology is relatively new, but this field is not. It is estimated that nature has evolved on Earth for approximately 3.8 billion years, and nature includes many materials, objects and processes that function on the macroscale to the nanoscale [4]. Thus, understanding the behaviors and properties of these materials and processes may facilitate the production of nanomaterials and nanodevices. Biomimicry, a term derived from the Greek word biomimesis, was defined by Otto Schmitt in 1957 and denotes the development of biologically inspired designs that are derived or adapted from nature [4]. The term biomimicry is relatively new, but our ancestors have looked to nature for the inspiration and know-how to develop various devices for many centuries [21,22]. Indeed, throughout history, many objects and beings, including bacteria, plants, soil, aquatic animals, shells and spider webs, have been found to have commercially interesting properties.

Bacterial flagella rotate at more than 10,000 rpm [23] and constitute an example of a molecular biological machine. The flagella motor is driven by proton flow caused by electrochemical potential differences across the cell membrane. The diameter of the bearings is approximately 20–30 nm, and the gap is approximately ≈ 1 nm [4].

Many billions of years ago, molecules began to organize themselves into the complex structures that gave rise to life. Photosynthesis uses solar energy to support plant life. The molecular assemblies present in the leaves of plants (such as chlorophyll) take the energy from sunlight and transform it into chemical energy to power the biochemical processes of plant cells, which have processes ranging from the nanometric to the micrometric scale. This technology has been exploited and developed for solar energy applications [4].

Some natural surfaces, including plant leaves with water repellents, are known to be superhydrophobic and self-cleaning because of their roughness (arising from nanostructures) and the presence of a wax coating [24]. Using roughness to imbue surfaces with superhydrophobicity and self-cleaning properties is of interest for many applications, including windows, windshields, exterior paints, ships, kitchenware, tiles, and textiles. Superhydrophobic surfaces can also be used for energy conversion and storage [25], whereas surfaces with low wettability can reduce the friction of contacting surfaces at machine interfaces [26].

The fixation structures present on the feet of various creatures, including many insects (e.g., beetles and flies), spiders and lizards, can adhere to a variety of surfaces and be used for locomotion. These structures cling to and detach from different types of surfaces [27,28]. The dynamic adhesion capacity is called reversible adherence or smart adhesion. Common adhesives leave residues and are not reversible. Thus, replicating the characteristics of gecko feet would facilitate the development of a super adhesive polymer tape capable of clean, dry, and reversible adhesion [4]. Such a tape would have potential applications in everyday objects and high-tech applications, such as, microelectronics.

Many aquatic animals can move at high speeds through water with low drag energy. For example, most shark species move through water with high efficiency. Shark skin is fundamental for this behavior, reducing friction, and exhibiting a self-cleaning effect that removes ectoparasites from its surface [4]. These characteristics are attributable to very small structures present in shark skin, called dermal denticles, which are ridges with longitudinal grooves that result in very effective mobility through water and minimize the adherence of barnacles and algae [4].

Speedo developed a full-body, shark skin-based swimsuit, called Fastskin, for elite swimming. Furthermore, the builders of boats, ships, and aircraft have also attempted to mimic shark skin to reduce drag and minimize the fixation of organisms on the surfaces of these craft. The mucus on the skin of aquatic animals, including sharks, acts as a barrier against the osmotic salinity of sea water, protects against parasites and infections, and functions as a friction-reducing agent. Artificial fish-derived mucus products are currently used to propel crude oil through the Alaskan pipeline [4].

Shells are natural nanocomposites with laminated structures and superior mechanical properties. Spider webs are made of silk fiber with high tensile strength. The materials and structures used in these objects have led to the development of various materials and fibers with high mechanical resistance [4]. Moths have eyes with multifaceted surfaces on the nanoscale and are structured to reduce the reflection of light. Their antireflective structure inspired the development of antireflective surfaces [29].

Biological systems’ self-healing abilities are highly interesting. For example, the chemical signals originating from the site of a fracture initiate a systemic response that sends agents to repair the injury. Inspired by these activities, various artificial self-structuring materials have been developed [30]. Human skin, for example, is sensitive to impact, which leads to purple discoloration of affected areas. This behavior led to the development of coatings that indicate impact-related damage [21].

Sensor arrays “mimicking” human senses, such as smell [31] and taste [32–35], consist of a set of sensors based on nanostructured materials and have been widely used in various applications, such as gas and liquid sensing, respectively [31,36–40].

Nanostructured materials are typically named according to their shapes and sizes and may take the forms of particles, tubes, wires, films, flakes and reservoirs, provided they have at least one nanoscale dimension [41,42]. One material that has been widely studied in nanotechnology is carbon nanotubes (Fig. 1.9), which are so named because their diameters are between 1 and 100 nm, although their lengths are typically on the order of hundreds of nanometers.

There are two main modes of developing nanotechnological materials. In the bottom-up approach, materials and devices are built from molecular components that are chemically organized according to the principles of molecular recognition. In contrast, in the top-down approach, nanoscale objects are built from other, larger scale objects, without control at the atomic level [44]. Many methods using these two modes have been reported.

In the bottom-up approach, a DNA molecule may, for example, be used to build other larger and well-defined structures using DNA and other nucleic acids [4]. Another example is the self-assembly technique, which can create self-organized molecular layer films [45,46]. Additionally, as previously discussed, an AFM tip can be used as a nanoscale recording head [19].

Due to top-down approach, many “solid-state” technologies used to create silicon-based microprocessors are now able to use resources on a scale smaller than 100 nm. Other techniques can also be applied to create devices known as Nano Electro Mechanical Systems (NEMS) derived from Micro Electro Mechanical Systems (MEMS) [4,5].

Examples of NEMS include microcantilevers with integrated nanotips for STM and AFM, AFM tips for nanolithography, molecular gears used to attach benzene molecules to the outer walls of carbon nanotubes, magnetic media used in hard disk drives, magnetic tape units [4], and ion beams that can directly remove or deposit materials in the presence of precursor gases. AFM can also be used in the top-down approach for the deposition of resistive films on a substrate that is subsequently subjected to an etching process [3–5,41,42].

Based on the manipulation of materials on the nanoscale, nanoelectronics can also be used to create computer memory using individual molecules or nanotubes capable of storing bits of information, molecular switches, nanotube transistors, flat-panel nanotube displays, integrated circuits, fast-access logic gates, nanoscopic lasers, and nanotubes as electrodes in fuel cells [4].

BioMEMS or BioNEMS are micro- or nanoelectromechanical systems with biological applications and have been increasingly used commercially [5,47–51]. These devices have been applied for chemical and biochemical analyses (biosensors) for medical diagnoses (e.g., DNA, RNA, proteins, cells, blood pressure, and toxin detection and identification) [51,52] and in implantable devices for controlled drug release [53]. Biosensors have also been developed to monitor liquids and gases [54–58]. A wide variety of biosensors are based on the principles of micro-/nanofluids [55,57,58]. Indeed, micro-/nanofluid devices offer the ability to work with smaller reagent volumes and reduced reaction times and facilitate performing various analyses simultaneously [52]. Other types of biosensors include micro-/nanoarrays able to perform one type of analysis millions of times [48–52].

Micro-/nanoarrays are used in biotechnology research to analyze DNA or proteins for disease diagnosis and drug discovery. They are also known as DNA arrays and can simultaneously identify thousands of genes. They consist of microarrays of silicon nanowires with diameters of a few nanometers, which are able to selectively interact with and even detect a single biological molecule, such as a DNA or a protein, or microarrays of carbon nanotubes capable of electrically detecting glucose. Detection occurs via nanoelectronics that sense small variations in an electric signal generated by the interaction of the analyte (e.g., DNA, protein or glucose) with the micro-/nanoassay [59].

BioMEMS and BioNEMS are also being developed to minimize invasive surgical procedures, including endoscopic surgery, laser angioplasty, and microscopic surgery. Other applications include implantable drug-release devices (micro-/nanoparticles encapsulating drug molecules in functionalized shells for activity at specific locations) or silicon capsules with nanoporous membranes for controlled release [4,48,49].

Nanoscale structures assumed key roles in technological development for a variety of reasons, some of which are listed next [1].

In quantum mechanics, the wave properties of electrons inside matter are influenced by nanoscale variations. Through the nanoscale design of materials, it is possible to vary their micro- and macroscopic properties, such as their charge capacity, magnetization and melting temperature, without altering their chemical composition [1].

The systematic organization of matter on the nanoscale is a key feature of biological systems. Nanoscience and nanotechnology seek to achieve powerful combinations of biology and materials science by adding artificial nanostructured systems to living cells and creating new materials using the self-structuring properties found in nature.

On the nanoscale, the surface areas of various materials are generally much larger than their geometric volumes, which favors their use in various applications, such as, composites for drug delivery and reaction systems and the storage of both chemical energy (such as hydrogen and natural gas) and electrochemical energy (batteries and supercapacitors) [2–5].

Macroscopic systems developed from nanostructures can have much higher densities than those obtained from microstructures. Therefore, when controlling the complexity of interactions on the nanoscale, these systems may be better conductors of electricity and thereby allow the development of novel electronic devices and smaller and faster circuits with more sophisticated functions and significantly reduced power consumption [2–5].

Currently, researchers from universities and companies worldwide are developing nanomaterials to create new products and lead to technological advances in engineering, chemistry, physics, computer science, and biology. Among these numerous technological advances, some easily recognized examples include the development of faster processors, more effective drugs, lighter and more resistant materials, new charge devices (e.g., more efficient batteries) and equipment with lower energy consumption and better image definition [e.g., organic light-emitting diode (OLED) screens] [2–5].

Nanotechnology represents a new world that is finally within our reach, thanks to quantum mechanics and sufficiently advanced simulation and analysis techniques. Currently, nanotechnology has important potential applications in all fields.

Due to technological advances in visualization and the ability to manipulating matter at the atomic and molecular levels, nanotechnology has become a major research theme for the development or improvement of products. Indeed, its popularity is reflected by the abundant news items reported in the media (television, radio, newspapers, magazines, and the Internet). The term “nanotechnology” has become synonymous with quality. Thus, the nanoscience knowledge domain will be of fundamental importance for the development of new technologies.

Both private and public sectors are strongly interested in this scientific field, as demonstrated by the study conducted by Allianz, which investigated many countries’ nanotechnology-development programs. Such programs are funded by and involve various organizations, ministries, government agencies, and the private sector. Countries that stand out are the United States, China, Japan, Germany, Spain, France, England, Sweden, Italy, the Netherlands, and Finland [63]. Since 2001, more than 60 countries have instituted national programs in nanotechnology [64].

To optimize these investments, long-term plans have also been studied, such as the Horizon 2020 plan (investment plan for 2014–20) launched by the European Union (EU). In this plan, after the closing of the Framework Panel 7 (FP-7) with an investment of €77 billion, an investment of €6.6 billion is destined for the Horizon 2020 program in six areas of nanotechnology: advanced manufacturing of nanotechnology, advanced materials, nanoelectronics, photonics and biotechnology. Additionally, €5 billion in investments from public and private investors are predicted. Japan has an investment plan lasting until 2020 that provides an investment of US $1 billion per year [65].

All nanotechnological successes depend on both investments and the relationships between research and development centers (universities and public or private companies). To contextualize the importance of such relationships, we highlight the case study reported by Sá [66], who investigated the actions taken by the University of Albany (the United States) to create the first college of nanotechnology as part of a larger center for research and development with the intent of building a regional cluster for nanoelectronics research: the College of Nanoscale Science and Engineering-Albany Nanotech. For the success of this project, in addition to the invested capital, it was necessary to establish new ways of thinking and administrating. Traditional models of relationships between universities and the corporate world were dispensed with, and a new model was created. Research professors with entrepreneurial interests were highly important for this development. Thus, the University of Albany concentrated on several characteristics, including building a university campus and a technology park and establishing an agent to promote regional and industrial development [66].

This study showed the importance of not only financial investment but also new ideas, the breaking of paradigms, and strategic and specific actions, which can be critical for the success of nanotechnological development.

Another factor, which is somewhat curious and can assist in the development of nanotechnology, has nothing to do with money or commercial interests. Instead, it relates to public commitment, combining civil society, and scientific and technological research. With the emergence of new policies, at least in the United States, Australia, and Europe, public commitment has become important in deciding the path of innovation. In Europe, for example, the Responsible Research Innovation (RRI) program seeks not only to align society with science but also to make research centers accessible to society, especially regarding decision-making about relevant problems. This type of engagement between civil society and the scientific world is a form of upstream public engagement, which is the opposite of downstream public participation, in which society participates only in the final stages of technological development, for example, after important decisions have already been made and the developed product is ready to enter the market. Upstream public engagement is a public commitment allowing civil society to provide input from the beginning regarding the course that scientific and technological research should take to produce new, beneficial products [67].

As mentioned previously, the success of nanotechnology is evident and have attracted high investiment. As a result, there is concern among governments and investors regarding the evaluation and justification of the impact of spending on nanotechnology. For example, in the United States and Japan, there are specialized programs for such evaluations: the Science of Science and Innovation Policy (SciSIP) and the National Institute of Science and Technology Policy (NISTEP), respectively. In addition, there is also great interest on the part of society and especially development agencies and investment sectors in the impact and quality of publications resulting from research and development [68]. Therefore, bibliometric and scientometric studies are used in the identification, quantification, qualification, classification, and frequency of publications in nanoscience and nanotechnology. Such studies have a certain level of complexity, and one way to contextualize this complexity is by discussing how such studies are conducted: searching for articles on relevant sites [for example, the Web of Science (WOS)] using keywords. In the case of nanotechnology, because of the large number of variations involving the term “nano,” “nano” itself can be used as a keyword. However, the articles generated from such a search may or may be relevant to nanoscience and nanotechnology, and thus, the results must be carefully evaluated. Thus, this type of study is as complex as the actual research in nanoscience and nanotechnology, and abundant relevant articles have been published in the area. One example is the study of Porter et al. [69], who evaluated the performance of software used to search for publications on the subject of nanotechnology. In the WOS, 406,000 papers and more than 53,000 micropatents and patents were found between 1990 and mid-2006. Another assessment performed from 1990 to mid-2011 indicated that 820,000 documents could be identified in the WOS [70]. Two other studies were conducted by Shapira and Wang: one study evaluated the quantity and quality of articles published from 2008 to 2009, identifying 91,500 articles published on the subject nanotechnology, among which only 67% were informative articles [64]. The other study evaluated the impact factor and quality of published papers. That study revealed that the quality of the publishing journal and the number of citations were linked the major sponsors of the study [68]. Stopar and Bartol conducted a very restricted evaluation of the scientific output in nanoscience and nanotechnology in 2012, searching for articles in the ten journals with the most publications containing the term “nano” in the title. Journals were selected by researching the core collection (old citation index) of the WOS. The Scopus database was also evaluated, revealing the same ten journals identified in the core collection of the WOS. These 10 journals were the Journal of Materials Chemistry, Journal of Physical Chemistry C, Applied Physics Letters, Journal of Nanoscience and Nanotechnology, Journal of Applied Physics, ACS Nano, Nano Letters, Nanotechnology, Nanoscale, and Materials Letters [71].

Among all the assessments made in this study, the most striking results was that in 2012, a total of 2,700 journals published articles with the term “nano” in the title, but of these 2,700 journals, only 50 published more than 200 articles; furthermore, the ten journals selected in the study had published approximately 9,000 articles on the subject of nanoscience or nanotechnology. Another interesting result was the number of compound terms containing the term nano that were found. In ascending order, the terms most commonly found were as follows: nanoparticle, nanowire, nanotube, nanostructur*, nanocrystal, nanocompos*, nanorod, nanoscale, nanofiber, nanopor*, nanoribbon, nanosheet, nanocluster, nanosphere, nanometer, nanomaterial, nanobelt, nanocube, nanopillar, nanoplate, nanopattern, nanodot, nanoflake, nanosize, nanohybrid, nanoplatelet, nanoantenna, nanoring, nanoimprint, nanosecond, nanopowder, nanomechanic, nanocapsule, nanoshell, nanogap, nanomembrane, nanoindent* and nanoflower [71].

Finally, this study reported the number of articles in the literature published over a 1-year period and indicated how complex it is to perform this type of study. Clearly, abundant scientific articles are produced, as indicated by the studies cited and by a simple search of the WOS. When we searched for titles included the top three most-cited keywords containing the term “nano,” according to a study by Stopar and Bartol covering 2012–15, we obtained the following results (Table 1.2)

The numbers listed previously were not subjected to scientometric or bibliometric evaluation; indeed, only a search for article titles containing the indicated nano-terms was performed. However, these results provide perspective regarding the vast number of articles in the literature. One thing is certain: all of these numbers are the result of the popularity of research in nanoscience and nanotechnology.

As shown, nanoscience and nanotechnology have provoked important changes in the political, economic, administrative, social, and scientific spheres. Given the data evaluated here, it may be concluded that more than half of the globe benefits from and participates in this new branch of science. Furthermore, financial investments increased during each studied period. Interest in this new science is attracting increasing attention from many sectors ranging from technology to health, and the dissemination of scientific research results, as reflected by the huge quantity of publications, indicates the popularity of this new scientific field.

The most easily identifiable applications are electronic devices: nanotechnology is critical to the development of various components, such as, microprocessors, digital screens, and batteries.

The production of data-storage chips begins with the wafer, which consists of a disk cut from a single silicon crystal with a diameter of at least 300 mm and is typically between 500 and 800 μm thick. Integrated circuit structures are built layer by layer on the surface of the chip using etching techniques, such as, lithography [72]. The development of the transistor (the building block of integrated circuits and microchips) was based on complementary metal–oxide semiconductors (CMOSs); transistors have existed for decades and are part of our everyday lives. The smallest of these structures was as low as 22 nm in 2015 (the “router” transistor) and is near the operating limit, approximately 5 nm, for metal–oxide semiconductor field-effect transistor technology; this limit is based on the high leakage current that should occur inside the chip and will likely be reached within the next 20 years [73]. These developments represent major technological challenges because of the manufacturing process itself and performing heat-management tests in circuits (a modern high-performance chip can dissipate heat at a density of 100 W·cm⁻², which exceeds the ability of a domestic kitchen hot plate) [74].

Silicon is envisaged as an important semiconductor material, but to fabricate ever smaller structures, new photoresistors must be developed. Furthermore, thin silicon oxide films become increasingly less efficient as they become thinner, and their leakage currents become very high. Thus, SiO₂ was replaced by physically thicker layers with higher dielectric constants. New semiconductors must satisfy some conditions, such as, high dielectric constants, thermal and kinetic stabilities, band shifts, good quality Si interfaces, and low defect densities. Hafnium oxides (HfO₂) have emerged as attractive oxides, typically with the incorporation of nitrogen. Ge has also been incorporated into the structure of CMOS transistors to maximize performance [75]. The origin of ferromagnetism is based on both electron charges and spin. Therefore, the miniaturization of magnetic memories has been limited not by the final size of the ferromagnetic domain but by the sensitivity of the magnetic sensors. In other words, the main limitation is not the ability to make very small storage cells but the ability to detect very small magnetic fields [74].

The influence of rotation on the electron conductivity was invoked by Nevill Mott in 1936 but remained virtually unexplored until the discovery of giant magnetoresistance (GMR) in 1988 [74,76]. The main application of spintronics (loosely defined as the field of devices in which electron spin plays a role) is the development of ultrasensitive magnetic sensors for magnetic reading memories. GMR is used for the reading and writing heads of computer hard disk drives [76].

A second type of magnetic sensor is based on the magnetic tunnel junction (MTJ), in which a very thin dielectric layer that is nonconductive under applied voltage separates the ferromagnetic layers (electrode) and the electron tunnel. The sensitivity of the magnetic field exceeds that of GMR devices. MTJ devices also have high impedance, allowing high output signal values. Unlike GMR devices, electrodes are magnetically independent and may have different critical fields to change the orientation of the magnetic moment. The first laboratory samples of MJT devices (NiFe-Al₂O₃-Co) were reported in 1995 [74].

As previously described, there are no limits on the demand for devices that are smaller, lighter, and more efficient and have lower power consumption. When merely considering the development of mobile telephone devices (cellular phones), in just 20 years, development in this segment has been remarkable. In 1993, smartphones were fiction, a distant possibility at best. At that time, at least in Brazil, cell phones were not prevalent. Furthermore, although they had existed since the 1980s, even in the 1990s, the predominant devices were expensive, large, and heavy; had antennas; and operated using analog networks.

Currently, cellular phones are energy-efficient machines, are fast and provide all the functions of notebook computers, and combine multiple devices into one, including a personal computer, digital camera, sound recorder, text and spreadsheet editor, gaming station, and Global Positioning System (GPS). There are also numerous manufacturers and a wide range of models and prices. The evolution of mobile phones went through a period of miniaturization, and now, with the advent of smartphones, these devices are growing again, providing increasing numbers of functions (Fig. 1.10). Recently, smart watches have also been developed that are similar to smartphones.

Another example from everyday life is the evolution of television sets and computer monitors, and the emergence of different displays in portable devices. Briefly, all of this evolution began in the mid-18th century with Charles Du Fay, who studied the electron emission from a heated metal surface, which is known as the thermoionic effect [77]. Since then, several studies on this subject were performed until it was concluded that this phenomenon was attributable to cathode rays [78]. These rays were further studied in 1897 by Joseph John Thomson [9], who found that cathode rays were simply electrons and that they behave as particles rather than waves. It should be noted that in parallel to the research of J.J. Thomson, Wilhelm Conrad Roentgen also investigated the behavior of cathode rays and discovered how the X-ray machines used in the medical field worked [79]. Finally, building on these discoveries (thermoionic effect and the nature of cathode rays), the kinescope was developed; this device was responsible for image formation in the first televisions and computer monitors [80].

The television sets and computer monitors that used cathode ray tubes for image generation have since been replaced by other devices because of the development of the liquid crystal displays (LCDs). LCD screens comprise a combination of polymers and glass slides coated with indium tin oxide (ITO) [81]. The discovery of liquid crystals is attributed to the botanist Friederich Reinitzer in 1888 [82], when he observed the double melting point of cholesteryl benzoate (Fig. 1.11). However, the term liquid crystal was coined by Coube Lehmann, who believed that the degree of fluidity was the only difference between liquid crystals and solid crystals. However, liquid crystals are actually characterized by the degree of molecular order between the long-range orientational and positional orders of a solid crystal and the long-range disorder of isotropic liquids and gases [83].

In the Web of Knowledge database, when the title search keyword “liquid crystal displays” is used, the first works that describe this technology can be seen to date back to 1968: Liquid Crystals—A Step Closer To Low-Voltage Displays (anonymous author) [85] and Reflective Liquid Crystal Television Display [86]. However, 99,644 other works are also found (searched on September 16, 2013) that describe the development and diverse applications of LCDs. Initially, the displays that used liquid crystal materials had very limited image resolutions and were used only in wristwatches and calculators [87]. An account of their development is given by Toshiaki Fujii et al. [87], who developed a LCD with a resolution capable of reproducing not only letters and numbers but also graphics, figure patterns, and even Chinese characters. In summary, this LCD revealed the possibility of replacing cathode ray tube monitors. The results reported in that article were based on a screen tested using a computer, and the authors were believed to have developed the first LCD monitor at the time. Given the constant evolution of this technology, currently, there is competition between LCD screens and OLEDs, which were first described by two researchers from Eastman Kodak in 1987. They developed an electroluminescent device with a thickness of 135 nm that operated at low voltage (below 10 V) [88]. Indeed, currently, OLEDs are LCDs’ main rivals (Fig. 1.12).

The basic structure of an OLED consists of one or more emissive (electroluminescent) polymeric layers (organic part) placed between a transparent anode and a metallic cathode. Typically, the organic layers are composed of a hole-transporting layer (HTL), an emitting layer (EL) and an electron-injection layer (EIL), and thus, a variety of architectures and desired effects can be achieved [90]. All OLEDs require at least one transparent electrode. Traditionally, ITO has been used, but the Earth’s supply of indium is very limited, and at current consumption rates, it may be completely exhausted within 2–3 years. Furthermore, constant advances in integration and miniaturization are causing the effective recycling of indium from discarded components to become increasingly complicated. Thus, there is great interest in the fabrication of transparent polymer additives containing a small proportion of carbon nanotubes for conductivity.

One additional advantage of organic electronic devices is their ability to be deposited on any substrate, including flexible and robust plastic sheets. New organic light-emitting polymers are currently in the research phase and have potential for the development of thinner and flexible displays with high resolution and low power consumption [90,91] (Fig. 1.13).

In addition to the development electronic devices, nanotechnology is used in all other areas, including health, sports, clothing, automotive, and food.

A natural textile fiber, such as, cotton has an intricate nanostructure. Many of the comfortable properties of traditional textiles result from a favorable combination of chemistry and morphology. These factors are what allow the properties of natural textiles to be equal or superior to those of synthetic materials. Furthermore, nanoadditives can increase some of the properties of natural textile fibers, such as, mechanical strength, durability, heat and flame resistance, self-cleaning capability, color, and antiseptic effect.

Some textiles release useful chemical substances passively or actively. These advanced functional fabrics are often used in special applications, serving as a type of “scaffold” for cells facilitating tissue regeneration and wound sterilization to facilitate healing [74]. Dr. Robert Burrell of the University of Alberta (Canada) developed dressings with silver nanocrystalline films in 1995 [92]. While working for Westaim Corp’s NUCRYST Pharmaceuticals, he invented Acticoat (Fig. 1.14), a silver-based dressing, which had antimicrobial properties and increased the healing rate. This dressing is often used in burn units and is now sold worldwide combined with common adhesive bandages. This work earned awards, including the World Union of Wound Healing Society Lifetime Achievement Award recognizing contributions to wound healing and, in 2009, the ASM Engineering Materials Achievement Award.

Wall papers with antibacterial properties have also been developed, in which zinc oxide (ZnO) nanoparticles are incorporated into the cellulose fibers and react with the gram-positive bacteria Staphylococcus aureus and gram-negative bacteria Escherichia coli, the main causes of nosocomial infections, and the fungus Aspergillus niger [94].

Tennis is a good example of the integration of nanotechnology in sports. Wilson, one of the largest tennis sporting goods manufacturers in the world, manufactures balls with less-permeable rubber than traditional balls (nanoclays are mixed with the rubber to achieve this effect) and lighter, more-resistant tennis racquets produced using carbon nanotube fiber structures [95].

Eyeglasses, sunglasses, windows, and even photographic camera lenses may also include nanometric particles that function as conductive polymers and change color based on the absorption of UV light from sunlight. This mechanism is known as “photochromism,” and today, it is widely commercially available.

In the automotive industry, nanotechnology has an increasingly important role in the development of new vehicles. The main overriding goal is to reduce vehicle weight without compromising other attributes, such as, safety. Therefore, researchers are especially interested in replacing the heavy metals used in components with lighter polymers that are reinforced by nanoparticulate materials or nanofiber additives. Other, more specific objectives include formulating lightweight, electrically conductive materials for use in fuel lines to prevent static electricity and abrasion-resistant paints, reducing friction, and developing lights (LED), automotive sensors, multimedia devices, and electronics [74]. Polymeric nanomaterials, such as, carbon nanotubes, have been used in bumpers with safety and resistance levels similar to those of conventional bumpers while being significantly lighter, directly influencing vehicle fuel consumption. In Brazil, Fiat, for example, developed its FCC II car with clay nanocomposites. The body is composed of fibers containing nanoclay, which is a clay with a nanoparticle-based chemical additive. This composite has characteristics similar to those of fiberglass but is lighter, cheaper, and easier to recycle [96].

Another example is the use of nanoparticles in automotive paints. Mercedes-Benz recently developed a special paint with nanometric paint bubbles that can regenerate small scratches in the paint. When a scratch occurs, these small bubbles break and release paint that covers the exposed area, improving both the protection and aesthetics of the vehicle. Additionally, a special paint has been developed that allowed a car painted yellow to change color with the application of a low current or because of the incidence of sunlight [97].

In the health field, substantial research and development has been invested in products using nanotechnology for controlled drug delivery and use in surgical catheters.

Nanomedicine is defined as the application of nanotechnology in human health. In recent decades in particular, medicine has been characterized by important technological advances, accompanied by an enormous and concomitant expansion of its ability to diagnose and cure diseases.

Molecular biology can be considered an example of conceptual nanotechnology because the structures involved are on the nanoscale. Furthermore, molecular biologists’ work increasingly involves nanometrology, such as, the use of microscopic scanning probes. As mentioned earlier, biomimicry is the use of nanotechnology to artificially recreate natural nanoscale materials, devices, and systems. Since Drexler presented biology as a “proof of principle” of nanotechnology [98], a close relationship has developed between biology and nanotechnology. Thus, nanotechnology can influence the health field, and the resulting social changes have greatly impacted human health. In other words, the impact of nanotechnology on human health is not restricted to the development of drug delivery systems or devices and equipment [74].

In the pharmaceutical industry, three major developments are currently predicted: sensing, automated diagnosis, and personalized pharmaceutical products. The development of ever smaller sensors able to penetrate the body using minimally invasive procedures, such as endoscopy, is an example of the direct application of nanotechnology. Researchers are even seeking to develop such sensors as permanently implanted devices. Indeed, these devices may be able to continuously monitor physiologically relevant physicochemical parameters, such as, temperature and the concentrations of selected biomarkers. Presently, one of the greatest challenges is the automatic diagnosis of disease [74]. The third development, which is believed to be the most accessible, is the creation of custom pharmaceuticals using microfluidic mixers and reactors; however, these methods are not based on nanoscale techniques.

Prostheses and biomedical devices must be biocompatible [74]. Implants that play structural roles, such as bone substitutes, should be assimilated by the host. When assimilation fails, the implant typically becomes coated with a layer of fibrous material, which can move, causing irritation and weakening the implant’s structural role. For implants in the bloodstream (arterial stents and, possibly, future sensors), the opposite behavior is required: Blood proteins should not attach to such devices. In this case, adsorption has two deleterious effects: The accumulation of protein layers may clog the blood vessel, and the adsorbed proteins may change and therefore appear foreign to the host organism, triggering inflammatory responses. Thus, to achieve the required assimilation behavior, structures with appropriate surfaces (textures) must be developed [74].

For nonimplanted medical devices, such as scalpels or needles, researchers are focusing on developments to improve their sterilization and decrease their coefficients of friction to minimize the physical force required to penetrate the skin and, thereby, minimize patients’ pain [74]. These improvements can be achieved by high-precision machining and rough surface finishing at the nanoscale. Long-term implants should be designed to minimize the chance of bacterial infection. Once bacteria colonize an implant, their phenotype generally changes so that the cells become “invisible” to the immune system and antibiotics, resulting in persistent inflammation without destruction of the bacterial colony [74].

Implants with contact surfaces, such as those used in arthroplasty, typically generate particles as a result of wear, which can be relatively large and cause inflammation [74].

The oldest well-documented example of the use of nanoparticles in medicine is Paracelsus’s deliberate synthesis of gold nanoparticles (called “soluble gold”) as a pharmaceutical formulation [74]. The use of nanoparticles in medicine has recently become a flourishing field. Applications include magnetic nanoparticles directed by external fields to the site of a tumor and then energized by an external electromagnetic field to kill the particles’ neighboring cells, nanoparticles acting as carriers for drugs and nanoparticles that can be used as markers for disease diagnosis [74]. The use of nanoparticles for drug release is being intensively researched and developed, and many products are undergoing clinical trials. A major obstacle for the successful development of new drugs is that many drugs that exhibit good therapeutic interactions with a target molecule (e.g., an enzyme) have very low solubility in water. However, these compounds can be encapsulated in nanoparticles with hydrophilic outer surfaces. Such surfaces also prevent adsorption and the triggering of an adverse immune response, such as, protein denaturation during the passage of the particle through the bloodstream [74]. Thus, this technique facilitates not only controlled drug release but also targeting these nanocapsules (Fig. 1.15) to the desired location and thus avoiding side effects in healthy organs, such as, those caused by the chemotherapeutic agents used to treat cancer [99].

Molecular biology and clinical research constitute an important market for nanoparticle. For example, nanoparticles may be useful as biomarkers: By coating them with chemical products with specific affinities for particular targets (e.g., antibodies), nanoparticles can be used to more easily map the locations of those targets using microscopy. Such particles may simply consist of heavy metals, which are easily visualized under an electron microscope, or fluorescent particles [74].

The use of toxic materials for cosmetic purposes (e.g., applying them to the skin of the face) has a long history, as in the case of antimony salts, which were popular among the Romans. Nanotechnology contributed to creating new sunscreen formulations using smaller nanoscale particles in their emulsions. The advantages of these new formulas mainly include better spreading of the emulsions and, thus, improved skin coverage. Furthermore, upon spreading, the particles become invisible to the naked eye, and the whitish color common in older formulations is avoided. Additionally, advances in our knowledge of toxicity yielded much more benign materials, although the recent use of very fine particles (e.g., zinc oxide nanoparticles in sunscreens) has generated further concern regarding the possibility of their penetration through the outer layers of the skin or into cells and causing unknown effects [74].

Robots (microscopic or nanoscopic) are extensions of existing ingestible devices that move slowly through the gastrointestinal tract and provide information (mainly images [74]). As noted by Hogg [100], the minimum future requirements for such devices are as follows: detection (chemical), communication (receiving information and transmitting information out of the body, communicating with other nanobots), locomotion, computing (highly miniaturized electronics would be very attractive for the construction of the on-board logic circuitry), and power (it is estimated that power on the order of picowatts would be sufficient to propel a nanobot at a speed of approximately 1 mm·s⁻¹). To be effective, these nanobots will likely need to operate in swarms, making the requirement that they be able to communicate increasingly important.

Nanoscale materials have been used to solve problems in various fields of research and development. From a simple package to a high-tech device, nanoscience is clearly of fundamental scientific importance.