Nanotechnology and Prime Materials

Transcription

1 Nanotechnology and Prime Materials

2 Applications (cont ) Higher surface area Higher optical absorption Higher solubility

3 Applications Nano medicine Nano biotechnology Green nanotechnology Energy applications Industrial applications Tunable electronic structure by reducing the size Potential applications has left to explore.

4 Applications Nano water purifiers. inexpensive energy generation. Pollution trace detection and treatment. Radically improved formulation of drugs, diagnostics and organ replacement. Greater information storage and communication capacities Interactive smart appliances; and increased human performance through convergent technologies.

5 Nanotechnology and Prime materials Metals: Iron, needle shape particles with diameters on the order of nm are produced. Widely used in magnetic recording for analog and digital data. Ironpalladium, and Iron-platinum (strong magnetization) alloys are used for groundwater decontamination, and magnetic storage media respectively.

6 Nanotechnology and Prime materials Aluminum, powders with size range of nm produced using plasma reactor. In a few thousandths of second a rod of solid material with a massive pulse of electrical energy, heating it to 50,000 C, followed by rapid cooling of the gas, the speed of cooling controls the size of the nano-particles. It is used for optical applications like scratch-resistant coatings for plastic lenses, biomedical applications, fuel cells, and solar energy applications.

7 Nanotechnology and Prime materials Nickel, powders are valued for their high conductivity and high melting point. Particles with sizes with various nanoscales are produced using CVD, wetchemical processes and gas-phase reduction. Multilayer ceramic capacitors have become the major application for these nanoparticles.

8 Nanotechnology and Prime materials Silver, known for its excellent conductivity and antimicrobial effects. Particles with sizes range of nm have been used as an ingredient in a biocide (a chemical substance killing living organisms), in transparent conductive inks and paste,

9 Nanofibers are defined as fibers with diameters from few nano to few hundred nanometers. They have lengths up to several millimeters. Particles having a diameter of few nanometers 9

10 Electrospinning It uses high voltage supply to draw fine fibers from a liquid. The high voltage produces an electrically charged jet of polymer solution which solidifies and leaving polymer nanofiber. 10

11 Electrospinning/ Nanofiber 2. Formation of Bending Instability Formation 11

12 Experimental Results/ SEM PVA nanofibers without silver 12

13 Experimental Results/ TEM PVA nanofibers containing 1wt% of silver nitrate 13

14 Experimental Results/ TEM PVA nanofibers containing 3wt% of silver nitrate 14

15 Experimental Results/ TEM PVA nanofibers containing 6wt% of silver nitrate 15

16 Applications 1:10 1:1000 1: Serial dilutions made the process of counting easier 16

17 Applications Comparison between bactericidal activity of negative control and pure PVA at two contact times (NG-E) (PVA-E) 3 hours incubation Negative control without nanomaterial (NG-E) (PVA-E) 6 hours incubation 17

18 Applications Comparison between bactericidal activity of negative control and PVA nanofibers incorporated with low and high concentration of silver nanoparticles after 3hours incubation. Negative Control PVA with 1wt% silver nitrate PVA with 6wt% silver nitrate 18

19 TiO 2 Fabrication/ Silver Deposition TiO 2 Fabrication Potentiostat / Galvanostat Silver Deposition/ Electrodeposition Method: Ti-TiO 2 / Cathode Pt/Anode Reference Electrode Electrolyte 19

20 Effect of Fluoride concentration Anodizing Time: 2hrs Anodizing Voltage: 40 DC-V Electrolyte: Ethylene glycol: DI Water (90:10 wt %) 0 M Ammonium Fluoride 0.15 M Ammonium Fluoride 0.36 M Ammonium Fluoride 20

21 Effect of applied voltage on tube diameters Ethylene glycol: DI Water (90:10 wt %)+ 0.15M NH 4 F 2hrs Anodization Mean Diameter nm Min Diameter nm Max Diameter nm SD 30 V V V

22 Silver Deposition / SEM, EDX Results Deposition without Doping Deposition after Doping 22

23 Applications Photo-voltaic: dye sensitised solar cells Gas-sensing devices Biomedical Water Disinfection In this study growth inhibition test in Liquid Medium was selected to evaluate the antibacterial activity against Escherichia Coli bacteria. 23

24 Antibacterial test 1:10 Dilution 1:100 Dilution 1:1000 Dilution 1:10000 Dilution 24

25 Application/ Antibacterial Test Results Negative Control Without any inhibitors TiO 2 Ag/ TiO 2 25

26 Copper, nanoparticles and nanowires are synthesized using thermal reduction or sonochemical (using ultrasound) methods. superior ability to conduct heat and electricity.

27 Figure 4b

28 Figure 4c Figure 4. SEM micrographs of a. a single and b. a pair of CuNWs at high magnifications and c. a bundle of nanowires at low magnification

29 Figure 5b Figure 5. TEM images of the copper nanowires in the fabricated films at a. low and b. high magnifications

30 Experimental Data Fitted /sq V, % Figure 6. Surface resistivity of copper nanowires/pmma nanocomposites as a function of the CuNWs volume content

31 Nanotechnology and Prime materials Gold, nanoparticles are easier to produce compare to other metals (due to the chemical stability). Colloidal gold has been used in medical applications; in a wide array of catalytic applications, e.g. for lowtemperature oxidation processes, and production of other nanoparticles; optical and electrical applications, as components for various probes, sensors, and optical devices.

32 Nanotechnology and Prime materials Iron Oxide, nanoparticles of ferric oxide are translucent to visible light but opaque to UV, application in ultra thin transparent coatings with enhanced UV-blocking capabilities. Magnetic properties of magnetite are used to improve various electromagnetic media for storage, like magnetic tapes, computer hard drives, and advance magnets.

33 Nanotechnology and Prime materials Aluminum Oxide, Nanosized powders of alumina, has a lower melting point, increased light absorption, improved dispersion in both aqueous and inorganic solvents. Are used to polish semiconductor wafers, in advance ceramics, and advance composite materials, for coating light bulbs and fluorescent tubes for uniform emission of light, clear coating to increase hardness, scratch and abrasion resistance, as a performance filler in tires, as a surface fiction agent, coating of high quality inkjet papers.

34 Nanotechnology and Prime materials Titanium Dioxide, the largest-volume inorganic pigment produced in the world, is widely used in surface coating, paper and plastic applications, as a filler and whitening agent. UV light blocking, additive to sunscreens, cosmetics, varnishes for the preservation of wood, textile fibers, and packaging films.

35 Nanotechnology and Prime materials Catalytic, photo-catalytic, self-sanitizing, selfcleaning capabilities. In photoelectrochemical solar cells, thermal coating, corrosion protection. As a component in various polymer composites to yield a product with a tunable refractive index and improved mechanical properties for photonics and electrical applications. Optical communication components (light scattering is significantly reduced).

36 Nanotechnology and Prime materials Zinc Oxide, larger UV blocking capability, and very transparent for visible light, make them invisible when they added to other materials like cosmetics, sunscreens and antifungal foot powders. Used in ceramics, and rubber processing (increase elasticity, toughness, abrasion resistance). Nanowires are used in UV nanolasers,

37 Nanotechnology and Prime materials In addition to the oxides mentioned above, nanoparticle versions of other compounds, such as antimony, chromium, germanium, vanadium, tungsten, are being developed and their possible uses are being explored.

38 Nanotechnology and Prime materials Advance Composites: nano-composites are formed when nanometer-sized particles of useful additives are blended with a polymer. Using materials made of nano composites in building structures like cars and airplanes, increases the life time of the structures and saves huge amount of energy. Advance Ceramics: ceramics in general, are inorganic, nonmetallic materials that are consolidated at high temperatures, usually starting as powder particles and ending as solid, usable forms. A typical ceramic contains complex crystals structures based on the various oxides and may involve covalent and ionic bonding.

39 Applications (Hydrogen Storage) Extremely promising form of energy storage. The process by which it releases its energy is very efficient. The only exhaust gas produced is pure water. Can be burnt like any other fuel it can also be used to produce electricity directly in a fuel cell. No need of higher operating temperatures.

40 Requirements and issues Materials must possess (1) High hydrogen absorption capacity (2) Fast hydrogenation dehydrogenation (3) minimal deterioration during hydrogenation cycling. 40

41 Advantages of using nanomaterials The absorption-release characteristics can be fine-tuned by controlling the particle sizes Usage of nanoparticles reduces diffusion distances for hydrogen and hence improves the hydrogen exchange The increased porosity and smaller size lead to increased diffusion-limited rates. High surface area to volume ratio increases the possibility of physisorption and chemisorption of hydrogen atoms 41

42 Nanotechnology and Environment Growing world population and need for larger natural resources which in turn has a negative impact on the environment. Nanotechnology can contribute solving the problems. It offers solutions to problems of resource usage, energy consumption, and waste generation. Less materials needed for product fabrication; better reuse of waste materials will be possible; and there will be new and renewable energy sources. Environmental improvements will be enabled by smart devices for environmental monitoring, pollution detection and control, and purification and remediation of polluted water, contaminated air and soil

43 For example, billions of batteries disposed in landfills pose an environmental problem, they also are a complete waste of a potential and cheap raw material. Batteries contain heavy metals such as mercury, lead, cadmium, and nickel, which can contaminate the environment. Researchers have managed to recover pure zinc oxide nanoparticles from spent Zn-MnO2 batteries alkaline batteries.

44 Nanotechnologies can play a role in providing a secure drinking water supply by enhancing purification and decontamination. They can offer more targeted and less concentrated chemical usage. Using nano catalysts in the transport and chemical industries to improve the efficiency of manufacturing systems, and reducing wastes it can keep the environment clean. The ability to detect the presence of toxic agents in our ecosystem air, water, and soil is of great importance for our health and the protection of our environment. Sensors which are less bulky, simple to operate, sensitive, fast, and less costly can be developed using nanotechnology for measurements and environmental monitoring.

45 For example, titanate nanofibers are used of as absorbents to remove radioactive ions from water. It was found that the unique structural properties of titanate nanotubes and nanofibers make them superior materials for removal of radioactive cesium and iodine ions in water. To clean up oil spills, Conventional clean-up techniques are not adequate to solve the problem of massive oil spills. In recent years, works are done to use nanotechnology as a potential solution to clean up oil spills. Several nanoparticles and molecules are developed and tested to either absorb or convert the oil spills for easier removal.

46 Hydrogen production from sunlight While hydrogen fuel is a clean energy carrier. However, we need to produce hydrogen, and that can be done using a several ways. One way is the gasification of coal which the bu product is very dirty. Another way is using electrolysis to generate hydrogen from water. In this technique, using renewable energy resources like wind, and solar is the cleanest way. Working on the nanoscale, it is shown that an inexpensive and environmentally friendly light harvesting nanocrystal array can be combined with a low-cost electrocatalyst that contains abundant elements to fabricate an inexpensive and stable system for photoelectrochemical hydrogen production.

47 Nanotechnology from Different Angle

48 Nanotechnology from Different Angle No matter which way you turn, nanotechnology seems poised to impact our lives to some degree over the coming years. As materials, structures, and devices are engineered in the nanometer size range, unique properties emerge that can potentially be exploited in many ways. The technology associated with manipulation at the nanoscale nanotechnology is underpinning research and development into new materials, medical diagnostics and therapeutics, energy management, sensors, biological interfaces, and electronics with properties that have the potential to revolutionize our society.

49 Nanotechnology from Different Angle First-generation nanotechnology products are commercially available now, and increasing global investment in nanotechnology suggests we are only at the beginning of what some have called "the next industrial revolution. However, as with previous industrial revolutions, the potential societal and economic promise of nanotechnology needs to be tempered by possible negative implications.

50 Nanotechnology from Different Angle The need to proactively develop responsible nanotechnology has been highlighted in a number of high profile reports and articles recently and is central to the many governments strategic plan for developing and implementing the technology. Nowhere will this be more important over the next few years than in workplaces where new materials, devices, and products are being manufactured.

51 Nanotechnology from Different Angle Nanotechnology is based on the unique properties manifest in nanometer-scale structures, and it is expected that resulting products will in turn present unique health and safety issues. The significance of these issues is not yet clear. What is becoming apparent, however, is that the successful development of nanotechnology relies on proactively understanding and addressing the potential risk to human health and safety. As occupational health researchers and professionals, this is the challenge to face today as society stands on the brink of the nanotechnology revolution.

52 Nanotechnology from Different Angle Unlike incidental particles, very little is known about engineered nanoparticles and how they interact with cells or human organisms. There are only few papers written on the environmental and health impacts of these particles; however, there is a wealth of knowledge on incidental nanoparticles and how these particles interact with biological organisms. Questions remain whether the engineered nanoparticles will act as a bulk solid or a molecular system

53 Nanotechnology from Different Angle There is very little available information regarding the hazards and risks posed by materials employed in nanotechnologies. Based on the results of a number of reviews, there is a short information note to advise those working in the area of nanotechnologies of the most appropriate approach to control exposure with the current degree of scientific uncertainty, companies should take a precautionary approach when dealing with nanomaterials. In practical terms, this will mean that steps should be taken to contain material and reduce exposure as far as possible.

54 Nanotechnology from Different Angle Could the same properties that make the tiny particles so effective also turn them into efficient troublemakers inside the human body? It's one of the most intriguing aspects of nanotechnology: Commonplace materials assume unpredictable and incredible characteristics at the molecular level. Tiny rolledup "nanotubes" of carbon graphite suddenly turn super strong and highly conductive, inert materials become highly reactive, and particles that once emitted red light appear blue on the nanoscale.

55 Nanotechnology from Different Angle As more and more nano-based consumer products arrive, scientists are beginning to worry that these unpredictable particles are holding back a few surprises -- ones that could harm human health or the environment. Researchers have conducted only a handful of studies on the health implications of nanotechnology.

56 Nanotechnology from Different Angle We absolutely know how these materials behave when they are larger. But when we engineer something that small, it changes all the fundamentals. Some are so new we don't even have adequate testing methods. Nobody is saying here it's a minor threat or a major threat -- we just don't know.

57 Nanotechnology from Different Angle In the range of nano scale, thousands of different types of particles exist, some possibly dangerous but many others completely harmless. We're looking at a whole batch of nanomaterials. You can't go classify all nanomaterials as bad or all as good."

58 Why Nanotechnology is Dangerous? Nanoparticles unknown properties Particles nature More surface area than volume ratio The smaller the particle the more toxic

59 Nanotoxicology Potential Exposures 1. Airborne contamination of workplace 2. Handling of product/material 3. Cleaning/Maintenance activities 4. Leakage/Spillage Accidents 5. Product Drying 59

60 Nanotoxicology Questions need to be addressed:: What happens to the nanoparticles that we digest or inhaled? Can we trace them in our body? How our body react to them? How much of them can be eliminated? How the particles affect our cells and organs,

61 Nanotoxicology Ecosystems Pathways: Air Water Soil Waste/wastewater/landfills

62 Nanotechnology from Different Angle Pros & Cons Pro: Green Materials, Green Chemistry, Con: The toxicology of these materials maybe time and environment dependent. What is not toxic under one condition may be become toxic under different conditions. Pro: Save materials, less materials are used as we are dealing with nanosize structures. Con: Actually, more materials are used to produce one type of nano structure. Pro: Save energy by producing more efficient solar cell, helping renewable energies, and so on. Con. More energy is used to produce the nano optical sources. Plus the life cycle of these devices are not studies properly. Pro: Environment benefits. Con: The environment cost (in terms of money and toxicology) was never evaluated for the environmental friendly materials.

63 Nanotechnology from Different Angle Pro: Look at the applications and benefits of carbon nanotubes, in solar cell, water filteration, in electronics, as catalysts, in energy storage,.. Con: have you ever checked the life cycle of these materials. Production of these materials is expensive and has a big impact on environment. Pro: atom by atom manufacturing, less waste of materials. Con: More time consuming, use various materials including more chemicals. Pro: Smaller structures save less materials, saves energy and help ecosystem Con: Smaller structure have much larger surface to volume ratio, more reactive, can cause toxicity, increases radicals in body, and damages more tissues.

64 Nanotechnology Challenges Do nanomaterials present new and unique risks for health and safety and for the environment? Can the potential benefits of nanotechnology be achieved while minimizing the potential risks?

65 Nanoparticles impacts on living organisms There are many unknown details about the impact and interaction of nanoparticles on biological systems and more information on the response of living organisms to the presence of nanoparticles of varying shape and size, various surface to volume ration and kind of chemical composition is needed to understand in order to evaluate the level of their toxicities on living systems.

66 Nanoparticles impacts on living organisms What are the effects of nanoparticles on the environment? There are very few publications on the effects of engineered nanoparticles on animals and plants in the environment. However, a number of studies have examined the uptake and effects of nanoparticles at a cellular level to evaluate their impact on humans; it can reasonably be assumed that the conclusions of these studies may be extrapolated to other species, but more research is needed to confirm this assumption. Moreover, careful examination and interpretation of existing data and careful planning of new research is required to establish the true impact of nanoparticles on the environment, and the differences with larger, conventional forms of the substances. Persistent insoluble nanoparticles may cause problems in the environment that are much greater than those revealed by human health assessments.

67 Anti-Bacterial Nano silver Nano Ag in socks kills the bacteria and prevent unpleasant odor Harmless to the person wearing it Upon washing, Nano Ag leaks into water supply and kills good bacteria Anti-bacterial Nano Silver 67

68 Nanoparticles impacts on living organisms Pros: Efficiency and Environmental Friendliness Molecular Scale Manufacturing ensures that very little raw material is wasted and that we make only what we intend to make, no more. Factories begin to look more like clean rooms. Many studies show how nanomaterials can be created that are not only safe, but also cost less and perform better than conventional materials. Financial Benefits for Countries involved in Nanotechnology Nanotechnology is expected to be over $3 trillion market by Each country involved, including have a bright financial future ahead when it comes to gaining money with nanotechnology.

69 Nanoparticles impacts on living organisms Cons: Arms for War On the instrumental level, concerns include the possibility of military applications of nanotechnology, in particular there is a possibility of nanotechnology being used to develop chemical weapons and because they will be able to develop the chemicals from the atom scale up, critics fear that chemical weapons developed from nano particles will be more dangerous than present chemical weapons. Fear of Uncertainty Nanotechnology is quite a new concept and some effects are time dependent so it's difficult for experts to predict the damage nanoparticles might do. There are concerns about how nano-particles may accumulate in nature. Could large amounts be ingested by fish? And if so, would if be harmful? Would the particles be passed along the food chain like DDT. Thresholds need to be determined. It's vital to find out how to remove or simply detect nanomaterials if they become problematic. What happens to nanoparticles such as silver nanoparticles which are used quite a bit, for example in certain socks. In an experiment reported at the American Chemical Society meeting, washed seven brands of nanosilver socks and then tested the wastewater. All but one pair leaked silver. That silver, of course, ends up in our sewers, rivers and lakes. Results like this have strengthened the calls among scientists and environmentalists for a closer examination of nanoparticles and their effects on humans and the environment. You can find nanosilver in products from clothing and shoes to mattresses and pillows to appliances Considering how quickly the market is expanding worldwide, scientists doubt that current regulations are sufficient. They also point out the lack of regulations that specifically address nanoparticles and say that not enough is being spent on their health effects.

70 Nanotechnology from Different Angle Assessing Risks of Nanomaterials Identify and characterize potential NM hazards Assess potential exposure scenarios Evaluate toxicity Characterize risk and uncertainty Communicate about risks

71 Nanoparticles impacts on living organisms Nanotoxicology is the field which studies potential health risks of nanomaterials. The extremely small size of nanomaterials means that they are much more readily taken up by the human body than larger sized particles. How these nanoparticles behave inside the organism is one of the significant issues that needs to be resolved. The behavior of nanoparticles is a function of their size, shape and surface reactivity with the surrounding tissue. The large number of variables influencing toxicity means that it is difficult to generalize about health risks associated with exposure to nanomaterials each new nanomaterial must be assessed individually and all material properties must be taken into account. Health and environmental issues combine in the workplace of companies engaged in producing or using nanomaterials and in the laboratories engaged in nanoscience and nanotechnology research. It is safe to say that current workplace exposure standards for dusts cannot be applied directly to nanoparticle dusts.

72 Nanoparticles impacts on living organisms Nanopollution is a generic name for all waste generated by nanodevices or during the nanomaterials manufacturing process. Nanowaste is mainly the group of particles that are released into the environment, or the particles that are thrown away when still on their products.

73 Nanotechnology from Different Angle People have encountered and ingested nanometer-size particles since the invention of fire -- soot is a good example. So are air pollutants such as smog.

74 Nanotechnology from Different Angle Some of the new concerns center on metal-containing nano-materials such as titanium dioxide and zinc oxide. Compounds like these have always been used as sun blocks -- the thick solid-colored lotions you see on lifeguards' noses -- but once mixed into the lotions at a nano level, they turn translucent. Scientists fear that if the metallic atoms in these lotions get into the body, they'll create free radicals and undergo oxidation reactions, literally pulling cells apart in a fashion similar to the way alcohol consumption and cigarette smoking destroy cells.

75 Nanotechnology from Different Angle Another worry about special nano-material properties that could cause harm: Experiments are done with brain medications that use nano-materials to more easily target and enter trouble spots (drug delivery). But the easy maneuvering enabled by these tiny particles' size could prove a detriment. One study found that, when present in water, carbon structures called buckyballs slipped into the brains of large-mouth bass and killed cells. The study, however, was inconclusive and intended only to open the door for more research.

76 Nanotechnology from Different Angle Some science interest groups, also contend that while many outstanding questions remain, it's hardly time to sound the warning bells. We don't necessarily believe that there's a need to be alarmist -- we have been exposed to some of the materials for a while. But certainly there's enough novelty and enough new production going on that it's worth evaluating." As it was for many other new technologies, it will take years before anyone knows for sure.

77 Nanotechnology from Different Angle Some nano-materials, such as fumed silica, carbon black and titanium dioxide, have been used for years but are just now being labeled nano. New nano-materials usually have unique structures, surface characteristics or other novel chemical, physical and/or biological properties. Nano-materials often have no value when considered in isolation but when incorporated into products or processes they enable the product to exhibit some new quality or function

78 Nanotechnology from Different Angle The health and environmental risks from exposure to nano-materials are not yet clearly understood. Many nano-materials are formed from nanometer-scale particles (nanoparticles) that are initially produced as airborne particles or liquid suspensions. Exposure to these materials during manufacturing and use may occur by inhaling them, skin contact or ingesting them. Very little information is currently available on the most important exposure routes, exposure levels and toxicology. The information that does exist comes primarily from the study of ultra-fine particles (typically defined as particles smaller than 100 nanometers in diameter).

79 Nanotechnology from Different Angle Ultra-fine particles that do not dissolve are more toxic, because smaller particles have a relatively larger surface area. There are strong indications that particle surface area and surface chemistry are primarily responsible for the toxic effects seen in cell cultures and test animals. Research is underway to determine the extent to which ultra-fine particles can penetrate the skin. There is also concern that inhaled nanoparticles may move from the lungs into other organs.

80 Nanotechnology from Different Angle Workers in nanotechnology-related industries have the potential to be exposed to uniquely engineered materials with novel sizes, shapes and physical and chemical properties at levels far exceeding ambient concentrations. Much research is still needed to understand the impact of these exposures on health and how best to devise appropriate exposure monitoring and control strategies. Until a clearer picture emerges, the limited evidence available would suggest caution when potential exposures to nano-materials may occur

81 Nanotechnology from Different Angle This new technology has tremendous potential across a number of areas in the economy and promise to improve our lives in different ways. Due to advancements in nanotechnology, its application in areas such as pollution reduction, new methods of energy production, and medical innovation is likely to have a positive effect on our lives in the near future. However, because the technologies are so new, they may have a hazardous impact on our health as well. The technology is very complicated and that there are potentially thousands of new substances that can be developed which, like chemicals, can have numerous different attributes. While we can quantify the potential for economic benefit and other benefits to society, presently science does not have the information necessary to quantify the potential for hazards or to develop a method for assessing those hazards.

82 Nanotechnology from Different Angle In most cases, nanoscale systems will alter in physical size upon interaction with an aqueous system. For example, it is very common for many nanostructures to adopt a different chemical form simply through relatively minor interactions; consequently, size is not a constant factor in biological interactions. Furthermore, the surface area can make up a sizeable fraction of these materials, and they can be derived to make many different biomedical systems. By changing surface coatings the nanomaterial toxicity can almost be completely altered.

83 Nanotechnology from Different Angle For example, changing the surface features of the materials can change a hydrophobic particle into a hydrophilic one. Hypothetically, surface coats could, for instance, make it possible to eat nanoscale mercury if it has the right surface coating, while it may be dangerous to eat nanoscale table salt if the surface coating was not correct. For this reason, the scientists typical view of toxicology, which is driven by the composition of an inorganic particle, may have to be modified for nanoscale materials, because the surface is going to affect different dimensions of environmental and health effects.

84 Nanotechnology from Different Angle INTERACTIONS WITH BIOLOGICAL SYSTEMS Chemists and engineers interested in creating biocompatible nanostructures need to understand their interactions with biological systems. It is suggested that the challenge that nanomaterials pose to environmental health is that they are not one material. It is difficult to generalize about them because, similar to polymers, they represent a very broad class of systems. Many engineered nanomaterials have precisely controlled internal structures, which are structures of perfect solids. Over a third of the atoms in a nanoparticle are at the surface, and these are extremely reactive systems, which in some cases can generate oxygen radicals however, nanoparticles can be tied up very tightly in covalent bonds and wrapped with a polymer.

85 Nanotechnology from Different Angle Because of the size of nanostructures, it is possible to manipulate the surface interface to allow for interactions with biological systems. With the correct coating particles below 50 nm can translocate into cells relatively easily and are able to interact with channels, enzymes, and other cellular proteins. Those particles above 100 nm, based primarily on size of the particles, have more difficulty. Through the interactions with cellular machinery, there is potential for medical uses, such as drug delivery and cellular imaging.

86 Nanotechnology from Different Angle While coating or covalently modifying the outer surfaces of nanomaterials eliminates the toxicity of most particles, questions remain about whether under environmental conditions as opposed to laboratory conditions, the nanomaterials will still be benign. In a recent study, it was demonstrated that if surface-modified C60 materials were irradiated to UVA (i.e., ultraviolet radiation of nm in wavelength) for 11 min or UVB (i.e. ultraviolet radiation of nm) for 22 min, cytotoxicity returns. Additional research suggests that air exposure and nanoparticle dose are also important for cytotoxic effects. When cadmium selenide (CdSe) quantum dots in a liver culture model are exposed to air or ultraviolet light, hepatocyte viability decreases as assessed by mitochondrial activity of QD-treated cultures.

87 Nanotechnology from Different Angle So, while these nanomaterials may be safe under laboratory conditions, a more reliable or maybe environmentally relevant endpoint is to weather these compounds under environmental conditions are safe..

88 Nanotechnology from Different Angle Fullerenes and other nanomaterials can accumulate in the body, depending on the dosing route. For oral administration, 98 percent of fullerenes are eliminated within 48 hours via feces and urine. The 2 percent that is not eliminated is found throughout the rest of the body. Intravenous dosing is rapidly transported to the liver (73 92 percent), the spleen (up to 2 percent), lung (up to 5 percent), kidney (up to 3 percent), heart (approximately 1 percent), and the brain (approximately 0.84 percent) within 3 hours. After 1 week, 90 percent of intravenously administered fullerenes are still in the body.

89 Nanotechnology from Different Angle Nanoparticles, including C60, metal QDs, and TiO2 can be redox active (oxide reduction), which may lead to DNA cleavage, oxidative stress, and/or an inflammatory response. For example, C60 fullerenes, if exposed to light, can either make singlet oxygen or be electron donors to make super oxide radicals. The potential dilemma is that not only does the immune system use super oxide radicals to kill foreign toxicants; the super oxide radicals can cause hydroxyl radicals, which can lead to DNA cleavage. The good news is that the body has some ability to prevent the undesired DNA cleavage through super oxide dismutase, part of the antioxidant defense system.

90 Nanotechnology from Different Angle Toxicity of Carbon Nanotubes In a recent study, it was tried to investigate the toxicity of carbon nanotubes, which are approximately 1 nm by 1 5 µm as a singular particle. However, due to strong electrostatic potential, they rarely exist as individual discrete particles and agglomerate into nanoropes. Following instillation of the carbon nanotubes into the lung, the tissue was analyzed by looking at cell proliferation, histopathology, lung weights, etc. at 24 hours, 1 week, 1 month, and 3 months post instillation. Through this paradigm, the researchers would be able to determine the initial, transient reaction, but also ask whether the toxicity was sustained or progressive.

91 Nanotechnology from Different Angle Fifteen percent of the animals died within the first 12 hours due to high agglomeration from electrostatic attraction, which essentially coated the airways of these animals. This was not because of the toxicity of the material, but rather because the material coated their airways. Thus, these animals died from suffocation because of the unique properties of carbon nanotubes.

92 Nanotechnology from Different Angle The animals that survived the first 24 hours post instillation survived through the 3 months. Exposure to carbon nanotubes produced only a transient inflammatory response at 24 hours, but this was acute, with no inflammatory effects seen at 3 months. Since carbon nanotubes are used in the electronics field for diode, transistors, cellular-phone signal amplifier, and ion storage for batteries. Particles need to be thought of as having inherent toxicity, and being carriers for organic molecules and metals.

93 Nanotechnology from Different Angle Researchers performed exposure assessments in the workplace. The results suggested that the dust was less than 53 µg/m3, which was extremely low. Most of the nanotubes were aggregated into nanoropes, which may not be respirable. Scientists cannot assume that all nanomaterials are the same as their bulk counterparts, which suggests that materials will need to be tested on a case-by-case basis, a process that may be infeasible because of resource constraint. It was suggested that priorities for studying particles based on surface coating, surface charge, and particle aggregation will need to be made.

94 Nanotechnology from Different Angle Singled Wall Carbon Nanotubes (SWCNT) Low concentration injection test Mice suffer from lung injuries after 7 to 90 days High concentration injection test More than 55% mortalities within less than 7 days Some mice have shown some sort of early tumour in their lungs

95 Nanotechnology from Different Angle Carbon nanotubes side effects: Exposure to carbon Nano killed water fleas Carbon nanotube have caused extensive brain damage and changed the physiological make-up of fish Nano carbon can travel through a mother s placenta Nano carbon can assist in the formation of free radicals

96 Nanoparticles impacts on living organisms How can inhaled nanoparticles affect health? Inhaled particulate matter can be deposited throughout the human respiratory tract, and an important fraction of inhaled nanoparticles deposit in the lungs. Nanoparticles can potentially move from the lungs to other organs such as the brain, the liver, the spleen and possibly the foetus in pregnant women. Data on these pathways is extremely limited but the actual number of particles that move from one organ to another can be considerable, depending on exposure time. Even within the nanoscale, size is important and small nanoparticles have been shown to be more able to reach secondary organs than larger ones.

97 Nanoparticles impacts on living organisms Another potential route of inhaled nanoparticles within the body is the olfactory nerve; nanoparticles may cross the mucous membrane inside the nose and then reach the brain through the olfactory nerve. Out of three human studies, only one showed a passage of inhaled nanoparticles into the bloodstream.

98 Nanoparticles impacts on living organisms Materials which by themselves are not very harmful could be toxic if they are inhaled in the form of nanoparticles. The effects of inhaled nanoparticles in the body may include lung inflammation and heart problems. Studies in humans show that breathing in diesel soot causes a general inflammatory response and alters the system that regulates the involuntary functions in the cardiovascular system, such as control of heart rate.

99 Nanoparticles impacts on living organisms What are the health implications of nanoparticles used as drug carriers? Nanoparticles can be used for drug delivery purposes, either as the drug itself or as the drug carrier. The product can be administered orally, applied onto the skin, or injected. The objective of drug delivery with nanoparticles is either to get more of the drug to the target cells or to reduce the harmful effects of the free drug on other organs, or both. Nanoparticles used in this way have to circulate long distances evading the protection mechanisms of the body. To achieve this, nanoparticles are conceived to stick to cell membranes, get inside specific cells in the body or in tumours, and pass through cells. The surfaces of nanoparticles are sometimes also modified to avoid being recognized and eliminated by the immune system. The use of nanoparticles as drug carriers may reduce the toxicity of the incorporated drug but it is sometimes difficult to distinguish the toxicity of the drug from that of the nanoparticle. Toxicity of gold nanoparticles, for instance, has been shown at high concentrations. In addition, nanoparticles trapped in the liver can affect the function of this organ. Nanoparticles have the potential to cross the blood brain barrier, which makes them extremely useful as a way to deliver drugs directly to the brain. On the other hand, this is also a major drawback because nanoparticles used to carry drugs may be toxic to the brain.

100 Nanoparticles impacts on living organisms How should harmful effects of nanoparticles be assessed? Traditionally, doses are measured in terms of mass because the harmful effects of any substance depend on the mass of the substance to which the individual is exposed. However, for nanoparticles it is more reasonable to measure doses also in terms of number of particles and their surface area because these parameters further determine the interactions of nanoparticles with biological systems. Because of the specific characteristics of nanoparticles, conventional toxicity tests may not be enough to detect all their possible harmful effects. Therefore, a series of specific tests was proposed to assess the toxicity of nanoparticles used in drug delivery systems. One mechanism of toxicity of nanoparticles is likely to be the induction of oxidative stress in cells and organs. Testing for interaction of nanoparticles with proteins and various cell types should be considered as part of the toxicological evaluation.

101 Nanoparticles impacts on living organisms The interaction of nanoparticles with living systems is affected by nanoparticle properties as: Size & Dimensions: It is possible that nanoparticles with size of few nanometer reach inside biomolecules and cross cell membranes. One of the possible ways that nanoparticles may get into our body system is inhalation. Reports of inhaled nanoparticles reaching the blood and may reach other target sites such as the liver, heart or blood cells. Because of their very small size, nanoparticles of any material have a much greater surface to volume ratio than larger particles. Therefore, relatively more molecules of the chemical are present on the surface. This may be one of the reasons why nanoparticles are generally more toxic than larger particles of the same composition.

102 Nanoparticles impacts on living organisms Chemical Composition: Nanoparticles may dissolve inside the body and their effects on organisms are the same as the effects of the composed chemicals. The toxicity of nanoparticles depends on their chemical composition, but also on the composition of any chemicals adsorbed onto their surfaces. (The surfaces of nanoparticles can be modified to make them less harmful to health.) Dose: The ability of nanoparticles to spread within the body.

103 Nanoparticles impacts on living organisms Solubility: The major emerging issue to be discussed in the context of the biological interactions of nanoparticles is related to those particles with little or no solubility, or being nondegradable at the locality where accumulation is observed. There remain many unknown details about the interaction of nanoparticles and biological systems. Some nanoparticles dissolve easily and their effects on living organisms are the same as the effects of the chemical they are made of. However, other nanoparticles do not degrade or dissolve readily. Instead, they may accumulate in biological systems and persist for a long time, a source of concerns.

104 Nanoparticles impacts on living organisms Surface Characteristics Depend on their surface structures, their chemistry, and their energy, nanoparticles will adsorb some biomolecules once they are in touch with tissues or body fluids. In practice, the surface of nanoparticles may be modified or functionalized to facilitate the interactions between nanoparticles and surrounding biomolecules.

105 Nanoparticles impacts on living organisms Shape: Although there is little definitive evidence, the health effects of nanoparticles are likely to depend also on their shape. A significant example is nanotubes, which may be of a few nanometres in diameter but with a length that could be several micrometres. A recent study showed a high toxicity of carbon nanotubes which seemed to produce harmful effects by an entirely new mechanism, different from the normal model of toxic dusts.

106 Key Factors: Composition and Structure Solubility Reactivity Surface Chemistry Aggregation Potential Surface Area Shape Density Particle Size 106

107 In Summary Limited number of nanomaterials have been evaluated to date Toxicological aspects and assessment of nano materials are just starting. Insoluble nanoparticles are the greatest cause of concern. Several studies have shown that some of them can pass through the various protective barriers of the living organisms. The inhaled nanoparticles can end up in the bloodstream after passing through respiratory or gastrointestinal protective mechanism. They may penetrate nerves and eventually brain. Most toxicity is linked to nanoparticles large surface area. Many substance like TiO 2 recognized as non-toxic material becomes toxic on nano scales.

108 In Summary Still due to the small number of studies, the short exposure period, the different composition of the nanoparticles tested, and other factors, the toxicological data remains insufficient. Toxic dose is usually measured in mass unit however, in case of nanoparticles due to large numbers and their large surfaces this unit is not appropriate anymore and should be measure in term of numbers and the surface of any given mass. Discouraging the aggregation and agglomerate among nanoparticles, usually they are coated by specific chemical which may change the toxicity of the nanostructures.

109 In Summary Current developments in nanotechnology are increasing at such a rapid pace that it is a challenge for any government to stay up-to-date with progress. Nanotechnology has received considerable attention from scientific communities and governments worldwide. The United States, France, Japan, and Canada have centers and government agencies where they make assessments of the potential risks and benefits to human health posed by nanotechnology

110 In Summary Nanotechnology is one of the priorities for the Canadian government. Canada wants to be a world leader in developing and applying twenty-first century technologies such as biotechnology, environmental technology, information and communication technologies, health technologies, and nanotechnology. The Canadian government also has realized that it is time to break down barriers between research disciplines and to foster multidisciplinary approach. In this spirit, the government in Canada no longer funds one lab working on one item in isolation and favors a multi-faculty approach, where people with different backgrounds (physicists, biologists, and chemists) can work together on nanotechnology issues.

111 In Summary The Canadian government sees its responsibility in terms of ensuring that their society will be able to interact with new technologies, contribute to them, and manage them as they develop. In order to do so, the Canadian government conducts discussions with many departments and agencies and holds workshops that bring people together and allow them to take leads on different issues. Hopefully, the Canadian government plans to continue this interdepartmental, interdisciplinary approach.

112 In Summary Some basic strategies approached by the government are: Encouraging basic research to achieve fundamental knowledge and understanding of nanoscale phenomena and processes. Promoting applied research in specific grand challenge areas to accelerate transition of scientific discovery into innovative technologies. Providing mechanisms to facilitate transfer of technology into commercial applications and to support basic and applied research. Establishing research programs to understand the social, ethical, health, and environmental implications of the technology.

113 In Quebec IRSST ( Institute de recherche Robert Sauve en sante et en securite du travail ) supporting researches on Safety and health effects of nanostructures.