Hina Aslam BS (hons) Chemistry
Government College University.
Table of Contents: Introduction ……………………………………………................ 03 Background ……………………………………………………… 04 Physical properties …………………............................................. 05 Sizing nanoparticles …………………………………………….. 10 Characterization ………………………………………………… 11 Synthesis of nanoparticles ……………………………………… 11 Advantages of synthesis ………………………………………… 19 Synthesis of Iron oxide nanoparticles ………………………… 20 Synthesis of Silver nanoparticles ………………………………. 21 Applications of nanoparticles ………………………………….. 22 Applications of nanoparticles in Consumer goods ……………. 26 Human and environmental health and safety ………………… 27 Innovative aspects of this project ……………………………… 28 Current state of the development in Pakistan …………………. 29 Collaboration sought …………………………………………... 30 References ……………………………………………………… 31
Nanoparticles Introduction: "A particle having one or more dimensions of the order of 100nm or less". In nanotechnology, a particle is defined as a small object that behaves as a whole unit in terms of its transport and properties. Particles are further classified according to size: in terms of diameter, fine particles cover a range between 100 and 2500 nanometers. On the other hand, ultrafine particles are sized between 1 and 100 nanometers. Similar to ultrafine particles, nanoparticles are sized between 1 and 100 nanometers. Nanoparticles may or may not exhibit size-related properties that differ significantly from those observed in fine particles or bulk materials. Although the size of most molecules would fit into the above outline, individual molecules are usually not referred to as nanoparticles. Nanoclusters have at least one dimension between 1 and 10 nanometers and a narrow size distribution. Nanopowders are agglomerates of ultrafine particles, nanoparticles, or nanoclusters. Nanometer-sized single crystals, or single-domain ultrafine particles, are often referred to as nanocrystals. Nanoparticle research is currently an area of intense scientific interest due to a wide variety of potential applications in biomedical, optical and electronic fields.
Transmission Electron Microscopy (a, b, and c) images of prepared mesoporous silica nanoparticles with mean outer diameter: (a) 20nm, (b) 45nm, and (c) 80nm. Scanning Electron Microscopy (d) image corresponding to (b). The insets are a high magnification of mesoporous silica particle.
Background: Although nanoparticles are generally considered an invention of modern science, they actually have a very long history. Nanoparticles were used by artisans as far back as the 9th century in Mesopotamia for generating a glittering effect on the surface of pots. Even these days, pottery from the Middle Ages and Renaissance often retain a distinct gold or copper colored metallic glitter. This so called luster is caused by a metallic film that was applied to the transparent surface of a glazing. The luster can still be visible if the film has resisted atmospheric oxidation and other weathering. Michael Faraday provided the first description, in scientific terms, of the optical properties of nanometer-scale metals in his classic 1857 paper. In a subsequent paper, the author (Turner) points out that: "It is well known that when thin leaves of gold or silver are mounted upon glass and heated to a temperature which is well below a red heat (~500 °C), a remarkable change of properties takes place, whereby the continuity of the metallic film is destroyed. The result is that white light is now freely transmitted, reflection is correspondingly diminished, while the electrical resistivity is enormously increased."
Review of literature: The first mention of some of the distinguishing concepts in nanotechnology (but predating use of that name) was in 1867 by James Clerk Maxwell when he proposed as a thought experiment a tiny entity known as Maxwell's Demon able to handle individual molecules. The first observations and size measurements of nano-particles was made during the first decade of the 20th century. They are mostly associated with Richard Adolf Zsigmondy who made a detailed study of gold sols and other nanomaterials with sizes down to 10 nm and less. He published a book in 1914. He used ultramicroscope that employes the dark field method for seeing particles with sizes much less than light wavelength. Zsigmondy was also the first who used nanometer explicitly for characterizing particle size. He determined it as 1/1,000,000 of millimeter. He developed the first system classification based on particle size in the nanometer range. There have been many significant developments during the 20th century in characterizing nanomaterials and related phenomena, belonging to the field of interface and colloid science. In the 1920s, Irving Langmuir and Katharine B. Blodgett introduced the concept of a monolayer, a layer of material one molecule thick. Langmuir won a Nobel Prize in chemistry for his work. In the early 1950s, Derjaguin and Abrikosova conducted the first measurement of surface forces. 4
Physical properties: Nanoparticles are of great scientific interest as they are effectively a bridge between bulk materials and atomic or molecular structures. A bulk material should have constant physical properties regardless of its size, but at the nano-scale size-dependent properties are often observed.
1. Surface area: Thus, the properties of materials change as their size approaches the nanoscale and as the percentage of atoms at the surface of a material becomes significant. For bulk materials larger than one micrometer (or micron), the percentage of atoms at the surface is insignificant in relation to the number of atoms in the bulk of the material. The interesting and sometimes unexpected properties of nanoparticles are therefore largely due to the large surface area of the material, which dominates the contributions made by the small bulk of the material.
2. Optical properties: Nanoparticles often possess unexpected optical properties as they are small enough to confine their electrons and produce quantum effects. For example gold nanoparticles appear deep red to black in solution. Nanoparticles of usually yellow gold and gray silicon are red in color. Gold nanoparticles melt at much lower temperatures (~300 °C for 2.5 nm size) than the gold slabs (1064 °C); And absorption of solar radiation in photovoltaic cells is much higher in materials composed of nanoparticles than it is in thin films of continuous sheets of material. I.E. the smaller the particles, the greater the solar absorption.
3. Uniformity: It is desirable to process a material in such a way that it is physically uniform with regard to the distribution of components and porosity, rather than using particle size distributions which will maximize the green density. The containment of a uniformly dispersed assembly of strongly interacting particles in suspension requires total control over interparticle forces. Monodisperse nanoparticles and colloids provide this potential. Monodisperse powders of colloidal silica, for example, may therefore be stabilized sufficiently to ensure a high degree of order in the colloidal crystal or polycrystalline colloidal solid which results from aggregation.
4. Functionalization: The surface coating of nanoparticles is crucial to determining their properties. In particular, the surface coating can regulate stability, solubility and targeting. Nanoparticles can be linked to biological molecules which can act as address tags, to direct the nanoparticles to specific sites within the body, specific organelles within the cell, or to follow specifically the movement of individual protein or RNA molecules in living cells. Common address tags are monoclonal antibodies, aptamers, streptavidin or peptides.
5. Quantum confinement: Other size-dependent property changes include quantum confinement in semiconductor particles. Metal, dielectric, and semiconductor nanoparticles have been formed, as well as hybrid structures (e.g., core-shell nanoparticles). Nanoparticles made of semiconducting material may also be labeled quantum dots if they are small enough (typically sub 10 nm) that quantization of electronic energy levels occurs. Such nanoscale particles are used in biomedical applications as drug carriers or imaging agents.
On quantum confinement
6. Surface plasmon resonance and super paramagnetism: surface plasmon resonance in some metal particles and superparamagnetism in magnetic materials. Ironically, the changes in physical properties are not always desirable. Ferromagnetic materials smaller than 10 nm can switch their magnetisation direction using room temperature thermal energy, thus making them unsuitable for memory storage.
Super Plasmon Resonance
Super Paramangetism in nanoparticles
7. Suspension: Suspensions of nanoparticles are possible since the interaction of the particle surface with the solvent is strong enough to overcome density differences, which otherwise usually result in a material either sinking or floating in a liquid.
8. Polymers (plastics): Clay nanoparticles when incorporated into polymer matrices increase reinforcement, leading to stronger plastics, verifiable by a higher glass transition temperature and other mechanical property tests. These nanoparticles are hard, and impart 8
their properties to the polymer (plastic). Nanoparticles have also been attached to textile fibers in order to create smart and functional clothing.
9. Liposome: Semi-solid and soft nanoparticles have been manufactured. A prototype nanoparticle of semi-solid nature is the liposome. Various types of liposome nanoparticles are currently used clinically as delivery systems for anticancer drugs and vaccines.
10. Emulsion stabilizing: Nanoparticles with one half hydrophilic and the other half hydrophobic are termed Janus particles and are particularly effective for stabilizing emulsions. They can selfassemble at water/oil interfaces and act as solid surfactants.
Schematic diagram of synthesis and stabilization of silver nanoparticles in drying oils.
Sizing nanoparticles: Perhaps the most important task at hand when making and characterizing nanoscale materials is to control the size of the particle. To an equal extent we also want to control the shape of the resulting material. Both are important parameters because as described earlier, nanoscale metals and semiconductors exhibit size and shape dependent optical, electrical and even chemical properties. The next most important task after making nanoscale materials is to determine their size. In this respect, a number of ways exist for sizing nanoscale materials. In the present laboratory we will use one of the techniques described below (dynamic light scattering) to verify the size and size distribution of chemically synthesized Au NPs. We will also provide images from another technique so that we can actually “see” what the particles look like. Furthermore, we will use these images as an independent way to size the particles and will verify that the two techniques provide similar values of the NP diameter.
Transmission electron microscopy (TEM): This is the most common technique for “looking” at nanoscale materials. TEM uses electrons instead of photons to image samples. In addition, electromagnetic instead of glass lenses are used to focus a beam of electrons on the sample. The transmitted electron beam is then reimaged On a detector to reveal a picture of the specimen. Because the classical diffraction limit of an electromagnetic wave is roughly half its wavelength, a beam of electrons resolves much finer things than photons (i.e. light). Despite its power, we will not use an actual TEM in this laboratory because of time constraints involved in teaching someone to use this instrument. It is also not conveniently available at the current time.
Au NP TEM
Characterization: Nanoparticle characterization is necessary to establish understanding and control of nanoparticle synthesis and applications. Characterization is done by using a variety of different techniques, mainly drawn from materials science. Common techniques are electron microscopy (TEM, SEM), atomic force microscopy (AFM), dynamic light scattering (DLS), x-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF), ultraviolet-visible spectroscopy, dual polarisation interferometry and nuclear magnetic resonance (NMR). Whilst the theory has been known for over a century (see Robert Brown), the technology for Nanoparticle tracking analysis (NTA) allows direct tracking of the Brownian motion and this method therefore allows the sizing of individual nanoparticles in solution.
Transmission Electron Microscopy image of magnetic Fe3O4 nanoparticle.
Synthesis of nanoparticles: The synthesis and application of nanoparticles is one of the most interesting fields of research from a basic and applied point of views. The method employed by our group is a micellar method that could be easily scaled-up and allows the control of the composition and size of the nanoparticle. Many of these nanomaterials are made directly as dry powders, and it is a common myth that these powders will stay in the same state when stored. In fact, they will rapidly aggregate through a solid bridging mechanism in as little as a few seconds.
Whether these aggregates are detrimental will depend entirely on the application of the nanomaterial. If the nanoparticles need to be kept separate, then they must be prepared and stored in a liquid medium designed to facilitate sufficient interparticle repulsion forces to prevent aggregation. Different process of synthesis of nanoparticles are as follow:
1. Synthesis of nanoparticles in microemulsion: The use of water-in-oil microemulsions for the synthesis of nanoparticles is one of the most promising methods. The application of this technology allows the preparation of the nanoparticles. The microemulsion technology has been applied for the synthesis of pure metal nanoparticles (Pt, Pd, Ir, Rh, Rh, Au, Ag, Cu) as well as for the preparation of the bimetallic nanoparticles (Pt/Pd, Pt/Ru, Pt/Ir, Pt/Rh). The method can also be used for the synthesis of multimetallic nanoparticles. In the case of bi and multimetallic nanoparticles the atomic composition can be modified according with the needs. Moreover, this methodology can be used for the preparation of different types of nanoparticles such as SiO2, CdS, ZnS, ZrO2, CaCO3, BaCO3, CdSe, TiO2, etc. The particle size of the nanoparticle ranges between 1-50 nm but is strongly dependent of the surfactant employed. The main advantage of this method is the different compositions and sizes that can be obtained. The catalytic and electrocatalytic properties of the nanoparticles depend on the state and cleanness of their surface. For that reason is very important to develop some decontamination procedures able to clean the surface of the nanoparticles without modifying the initial structure and surface composition of the nanoparticles. This decontamination will allow the application of the nanoparticles with their complete catalytic or electrocatalytic properties. In the Chemistry-Physics Department some decontamination protocols able to obtain these requirements have been developed.
Synthesis of Cadmium Sulfide Nanoparticles: Hexadecyltrimethylammonium bromide has a long hydrophobic chain and a polar head group.
The molecule does not dissolve well in either aqueous or organic solvents. In an organic solvent containing a small amount of water the hexadecyltrimethylammonium bromide traps the aqueous portion in a micelle sphere with the polar heads facing in and the non-polar tails facing out. The relative amount of pentanol cosurfactant controls the size of the micelle. Mixing hexadecyltrimethylammonium bromide pentanol micelles of CdCl 2 with similar micelles containing Na2S produces nanoparticle CdS since the aqueous solution serves as a nanoreactor and the particles cannot grow bigger than the micelle. The pentanol also acts as a capping agent to stabilize the CdS particles. The formation of CdS nanoparticles can be detected by spectroscopy since quantum size effects make the visible absorption spectra different than that of bulk CdS.
A water-in-oil microemulsion droplet.
Procedure: Test the reagents by adding a drop of aqueous Cd +2 to a drop ofaqueous S-2. A yellow color should appear if the Na2S solution is good. If the mixture remains clear, remake the Na2S solution.
In a cuvet, add an equal amount of aqueous 0.012 M Cd+2 and aqueous 0.012 M S2 . Record your observations and immediately obtain the visible absorption spectrum.
Add 0.20 g hexadecyltrimethylammonium bromide to a test tube. Add a stir bar. Clamp over a magnetic stirrer.
Add 4.0 mL heptane and 1.0 mL pentanol to the hexadecyltrimethylammonium bromide. Stir to give a suspension.Transfer half the suspension to a second tube. Stir both solutions to maintain the suspension.
To one test tube, add 0.1 mL (3 drops) of 0.012 M CdCl 2. The solution will clear as hexadecyltrimethylammonium bromide micelles containing CdCl2 form. To the second test tube, add 0.1 mL (3 drops) of 0.012 M Na2S. The solution will clear as hexadecyltrimethylammonium bromide micelles containing Na2S form. Join the two solutions and record the absorption spectrum of the solution.
2. Synthesis of nanoparticles in colloidal systems: The preparation of nanoparticles in colloidal systems is one of the most well known methods for the synthesis of nanomaterials. Moreover, this methodology allows, in several cases, synthesize nanoparticles with some preferential orientations/shapes and it is very well-known that the shape of the nanoparticles influences their optical, electronic, catalytic and electrocatalytic properties. This fact is specially important when the nanoparticles are going to be applied in electrocatalytic or catalytic reactions which are sensitive to the structure of the catalyst. The application of this method to electrocatalysis is a really innovative concept. The main advantage of using this method is the possibility of controlling the shape of the particles. The particle size of the nanoparticle ranges between 5-50 nm but again is strongly dependent of the capping material employed. Thus, different shapes, with different properties, can be prepared (cubics, tetrahedral, spherical, truncated octahedral). Using this methodology Pt nanoparticles of different shapes have been prepared. As an example the following pictures are presented: Colloidal Pt nanoparticles
In a similar way, Au nanoparticles can be also prepared. This method can be applied to other noble metals and their alloys. Colloidal Au nanoparticles
Nanostars of vanadium(IV) oxide
3. Synthesis of nanorods: Colloidal systems can be also applied for the synthesis of Au nanorods. The synthesis is achieved using a seeding growth method. With this synthesis length of nanorods can be controlled from 20 nm to 1 micrometre aproximately. Optical properties of this nanorods are related to the size of the particles and different colours can be obtained, red, purple, black, etc. Thus, controlling length of nanorods different colours can be prepared. Moreover, Au nanorods can also be applied in electrocatalysis.
Au nanorod Various gold nanoparticle shapes such as spheres, rods, wires, and cubes have been prepared and characterized using standard processing techniques by researchers. By varying the shape of the materials, their vibrant optical properties can be suitably tuned from the visible to the IR region of the spectrum. Also enhanced plasmonic properties make Au nanorods of interest for a variety of sensing and biological applications.
Seed mediate process: Au nanorods are synthesized in a two-step seed mediate Process. The surfactant cetyltrimethylammonium bromide (CTAB) is used as a surface passivant. Au nanoparticle seeds are introduced to a growth solution containing excess CTAB and HAuCl from which the nanorods are grown off the surface of the seeded nucleates. The final rod-like structure possesses a surfactant bilayer on the surface, thus imparting a significant positive charge to the materials, which is the driving force for this solution stability.
. Au nanorods
Layer-by-layer assembly: The layer-by-layer (LBL) assembly method, combined with the seeded growth technique, has been used to deposit gold shells on the surface of hematite (α-Fe2O3) spindles. The LBL method yields dense coatings of preformed Au nanoparticles, while AuCl−4 ions are further reduced by a mild reducing agent, thicker, rough nanostructured shells can be grown.
Green synthesis: Gold nanorods can be prepared by electrochemically reducing gold salts in a concentrated surfactant solution.The procedure uses Silver nitrate, Ascorbic acid, Sodium borohydride, seed solution, gold solution, & CTAB and Au nanorods with a unidirectional pin-like morphology have been prepared on the surface of glassy carbon electrodes via a potential-step electro deposition method from H2SO4 solution containing Na[AuCl4].
Researchers have discovered a new method to create branched nanorods, such as those in this scanning electron microscope image. Such nanorods could one day enable new nanoscale thermoelectric devices for power generation, as well as nanoscale heat pumps for cooling hot spots in nanoelectronics devices.
Advantages of synthesis: • • • •
Customization of the process of synthesis, test, scale-up and technology transfer to the company. Use of decontaminated protocols for the cleaning of some particles. Techniques appropriated for metallic, bimetallic and multimetallic particles. Also applyable to other compounds as SiO2, CdS, ZnS, ZrO2, CaCO3, BaCO3, CdSe, TiO2, etc. 19
1. Synthesis of Iron oxide nanoparticles: Iron oxide nanoparticles are iron oxide particles with diameters between about 1 and 100 nanometers. The two main forms are magnetite (Fe3O4) and its oxidized form maghemite (γ-Fe2O3). They have attracted extensive interest due to their superparamagnetic properties and their potential applications in many fields (although Cu, Co and Ni are also highly magnetic materials, they are toxic and easily oxidized). Applications of iron oxide nanoparticles include terabit magnetic storage devices, catalysis, sensors, and high-sensitivity biomolecular magnetic resonance imaging (MRI) for medical diagnosis and therapeutics. These applications require coating of the nanoparticles by agents such as long-chain fatty acids, alkyl-substituted amines and diols.
Iron oxide nanoparticles
Synthesis by Co-precipitation method: The preparation method has a large effect on shape, size distribution, and surface chemistry of the particles. It also determines to a great extent the distribution and type of structural defects or impurities in the particles. All these factors affect magnetic behavior. By far the most employed method is coprecipitation. This method can be further divided into two types. In the first, ferrous hydroxide suspensions are partially oxidized with different oxidizing agents. For example, spherical magnetite particles of narrow size distribution with mean diameters between 30 and 100 nm can be obtained from a Fe(II) salt, a base and a mild oxidant (nitrate ions). The other method consists in ageing stoichiometric mixtures of ferrous and ferric hydroxides in aqueous media, yielding spherical magnetite particles homogeneous in size. In the second type, the following chemical reaction occurs: 2Fe3 + Fe2 + 8OH-→ Fe3O4 + 4H2O
Optimum conditions for this reaction are pH between 8 and 14, Fe+3/Fe+2 ratio of 2:1 and a non-oxidizing environment. Being highly susceptibile to oxidation, magnetite (Fe3O4) is transformed to maghemite (γFe2O3) in the presence of oxygen: Fe3O4 + 2H → γFe2O3 + Fe2 + H2O The size and shape of the nanoparticles can be controlled by adjusting pH, ionic strength, temperature, nature of the salts (perchlorates, chlorides, sulfates, and nitrates), or the Fe(II)/Fe(III) concentration ratio.
Tiny iron oxide nanoparticles
2. Synthesis of Silver nanoparticles: Silver nanoparticles are nanoparticles of silver, i.e. silver particles of between 1 nm and 100 nm in size. While frequently described as being 'silver' some are composed of a large percentage of silver oxide due to their large ratio of surface to bulk silver atoms.
Synthesis by wet chemistry: There are several wet chemical methods for creating silver nanoparticles. Typically, they involve the reduction of a silver salt such as silver nitrate with a reducing agent like sodium borohydride in the presence of a colloidal stabilizer. Sodium borohydride has been used with polyvinyl alcohol, poly(vinylpyrrolidone), bovine serum albumin (BSA), citrate and cellulose as stabilizing agents. In the case of BSA, the sulfur-, oxygen- and nitrogen-bearing groups mitigate the high surface energy of the nanoparticles during the reduction. The hydroxyl groups on the cellulose are reported to help stabilize the particles. Polydopamine coated magnetic-bacterial cellulose contains multifunctional groups, which acts as a reducing agent for in situ preparation of reusable antibacterial Agnanocomposites Article . Citrate and cellulose have been used to create silver nanoparticles independent of a reducing agent as well. An additional novel wet chemistry method used to create silver nanoparticles took advantage of ß-D-glucose as a reducing sugar and a starch as the stabilizer.
Also, it is important to note, not all nanoparticles are created equal. The size and shape have been shown to have an impact on its efficacy. Additionally, crystal facet size, oxide content and several other factors could also affect the antimicrobial properties.
TEM image of a two-dimensional silver nanoparticle superlattice and (inset) the histogram of the nanoparticles.
Applications of nanoparticles: Market applications: • • •
Optical, magnetic, catalytic and electrocatalytic properties. Sensors. Catalysts (supported and unsupported) for batteries, fuel cells, gas diffusion electrodes, etc.
• • • • •
Ceramic materials. Pigments. Textile engineering. Water treatment. Silver-based consumer products e.g, Cathode in a silver-oxide battery.
Laser applications: The use of nanoparticle distributions in laser dye-doped poly(methyl methacrylate) (PMMA) laser gain media was demonstrated in 2003 and it has been shown to improve conversion efficiencies and to decrease laser beam divergence. Researchers attribute the reduction in beam divergence to improved dn/dT characteristics of the organic-inorganic dye-doped nanocomposite. The optimum composition reported by these researchers is 30% w/w of SiO2 (~ 12 nm) in dye-doped PMMA.
Medical use of nanoparticles: • • • • • •
Bone cement Surgical instruments Surgical masks Wound dressings Polymeric nanoparticle Liposome
Silver Nanoparticles can stop AIDS Infections: According to research, this mode of antiviral action allows silver nanoparticles to inhibit HIV-1 infection. Silver nanoparticles are effective virucides as they inactivate HIV particles in a short period of time, exerting their activity at an early stage of vairal application (entry or fusion) and at post entry stages.
Catalytic uses of nanoparticles: Chemical catalysis benefits especially from nanoparticles, due to the extremely large surface to volume ratio. The application potential of nanoparticles in catalysis ranges from fuel cell to catalytic converters and photocatalytic devices. Catalysis is also important for the production of chemicals. Platinum nanoparticles are now being considered in the next generation of automotive catalytic converters because the very high surface area of nanoparticles could reduce the amount of platinum required.
Uses of nanoparticles in Aerospace: Lighter and stronger materials will be of immense use to aircraft manufacturers, leading to increased performance. Spacecraft will also benefit, where weight is a major factor. Nanotechnology would help to reduce the size of equipment and there by decrease fuel-consumption required to get it airborne. Hang may be able to halve their weight while increasing their strength and toughness through the use of nanotech materials.
Application of nanoparticles in construction: In building construction nanomaterials are widely used from self-cleaning windows to flexible solar panels to wi-fi blocking paint. The self-healing concrete, materials to block ultraviolet and infrared radiation, smog-eating coatings and lightemitting walls and ceilings are the new nanomaterials in construction. Nanotech-enabled
sensors can monitor temperature, humidity, and airborne toxins which needs nanotech based improved batteries. The building components will be intelligent and interactive since the sensor uses wireless components,it can collect the wide range of data.
Use of nanoparticles in steel industry: Steel has been widely available material and has a major role in the construction industry. The use of nanoparticles in steel helps to improve the properties of steel. The fatigue ,which lead to the structural failure of steel due to cyclic loading, such as in bridges or towers. The current steel designs are based on the reduction in the allowable stress, service life or regular inspection regime. The addition of copper nanoparticles reduces the surface un-evenness of steel which then limits the number of stress risers and hence fatigue cracking. Advancements in this technology using nanoparticles would lead to increased safety, less need for regular inspection regime and more efficient materials free from fatigue issues for construction. The nano-size steel produce stronger steel cables which can be in bridge construction .
Nanoparticles in glass: There is a lot of research being carried out on the application of nanotechnology to glass. Titanium dioxide (TiO2) nanoparticles are used to coat glazing since it has sterilizing and anti-fouling properties. The particles catalyze powerful reactions which breakdown organic pollutants, volatile organic compounds and bacterial membranes. The TiO2 is hydrophilic (attraction to water) which can attract rain drops which then wash off the dirt particles. Thus the introduction of nanotechnology in the Glass industry, incorporates the self cleaning property of glass. Fire-protective glass is another application of nanotechnology. This is achieved by using a clear intumescent layer sandwiched between glass panels (an interlayer) formed of silica nanoparticles (SiO2) which turns into a rigid and opaque fire shield when heated.
Use of nanoparticles in coatings: Nanoparticles are being applied to paints to obtain the coatings having self healing capabilities and corrosion protection under insulation. Since these coatings are hydrophobic and repels water from the metal pipe and can also protect metal from salt water attack. Nanoparticle based systems can provide better adhesion and transparency .The TiO2 coating captures and breaks down organic and inorganic air pollutants by a photocatalytic process ,which leads to putting roads to good environmental use.
Vehicle manufacturers using nanoparticles: Much like aerospace, lighter and stronger materials will be useful for creating vehicles that are both faster and safer. Combustion engines will also benefit from parts that are more hard-wearing and more heat-resistant.
Applications of nanoparticles in Consumer goods: Use of nanoparticles are already impacting the field of consumer goods, providing products with novel functions ranging from easy-to-clean to scratch-resistant. Modern textiles are wrinkle-resistant and stain-repellent; in the mid-term clothes will become “smart”, through embedded “wearable electronics”. Already in use are different nanoparticle improved products. Especially in the field of cosmetics, such novel products have a promising potential.
1. Foods: Complex set of engineering and scientific challenges in the food and bioprocessing industry for manufacturing high quality and safe food through efficient and sustainable means can be solved through use of nanoparticles. Bacteria identification and food quality monitoring using biosensors; intelligent, active, and smart food packaging systems; nanoencapsulation of bioactive food compounds are few examples of emerging applications. This technology can be applied in the production, processing, safety and packaging of food. A nanocomposite coating process could improve food packaging by placing anti-microbial agents directly on the surface of the coated film.
2. Household: The most prominent application of nanoparticle in the household is self-cleaning or “easy-to-clean” surfaces on ceramics or glasses. Nanoceramic particles have improved the smoothness and heat resistance of common household equipment such as the flat iron.
3. Optics: The first sunglasses using protective and anti-reflective ultrathin polymer coatings are on the market. For optics, scratch resistant surface coatings based on nanocomposites are available. Nano-optics could allow for an increase in precision of pupil repair and other types of laser eye surgery.
4. Textiles: The use of engineered nanofibers already makes clothes water- and stainrepellent or wrinkle-free. Textiles with a nanotechnological finish can be washed less frequently and at lower temperatures. It has been used to integrate tiny carbon particles membrane and guarantee full-surface protection from electrostatic charges for the wearer.
5. Cosmetics: One field of application is in sunscreens. The traditional chemical UV protection approach suffers from its poor long-term stability. A sunscreen based on mineral nanoparticles such as titanium dioxide offer several advantages. Titanium oxide
nanoparticles have a comparable UV protection property as the bulk material, but lose the cosmetically undesirable whitening as the particle size is decreased.
6. Agriculture: Applications of nanoparticles have the potential to change the entire agriculture sector and food industry chain from production to conservation, processing, packaging, transportation, and even waste treatment. NanoScience concepts and Nanotechnology applications have the potential to redesign the production cycle, restructure the processing and conservation processes and redefine the food habits of the people. Major Challenges related to agriculture like Low productivity in cultivable areas, large uncultivable areas, Shrinkage of cultivable lands, Wastage of inputs like water, fertilizers, pesticides, Wastage of products and of course Food security for growing numbers can be addressed through various applications of nanoparticles in agriculture.
Human and environmental health and safety: Studies of the health impact of airborne particles are the closest thing we have to a tool for assessing potential health risks from free nanoparticles. These studies have generally shown that the smaller the particles get, the more toxic they become. This is due in part to the fact that, given the same mass per volume, the dose in terms of particle numbers increases as particle size decreases.
Effect of nanoparticles on human health: Nanoparticles present possible dangers, both medically and environmentally. Most of these are due to the high surface to volume ratio, which can make the particles very reactive or catalytic. They are also able to pass through cell membranes in organisms, and their interactions with biological systems are relatively unknown. A recent study looking at the effects of ZnO nanoparticles on human immune cells has found varying levels of susceptibility to cytotoxicity. Despite these laboratory findings, free nanoparticles in the environment may rapidly agglomerate and thus leave the nano-regime. Nature itself presents many nanoparticles to which organisms on earth may have evolved immunity (such as salt particulates from ocean aerosols, terpenes from plants, or dust from volcanic eruptions). According to the San Francisco Chronicle, "Animal studies have shown that some nanoparticles can penetrate cells and tissues, move through the body and brain and cause biochemical damage they also have shown to cause a risk factor in men for testicular cancer. But whether cosmetics and sunscreens containing nanomaterials pose health risks remains largely unknown, pending completion of long-range studies recently begun by the FDA and other agencies." Diesel nanoparticles have been found to damage the cardiovascular system in a mouse model. 27
Effect of nanoparticles on environment: Nanoparticles may also enter the body if building water supplies are filtered through commercially available nanofilters. Airborne and waterborne nanoparticles enter from building ventilation and wastewater systems.
Effect of nanoparticles on societal issues: As sensors become more common place, a loss of privacy may result from users interacting with increasingly intelligent building components. The technology at one side has the advantages of new building material. The otherside it has the fear of risk arises from these materials. However, the overall performance of nanomaterials to date, is that valuable opportunities to improve building performance, user health and environmental quality.
Innovative aspects of this project: • • •
Possibilities of developing synthesis processes under customer’s requirements (sizes / shapes / composition). Electrocatalytic properties of nanoparticles are improved as a function of the size, and atomic composition of the nanoparticles. Synthesis of new catalyst and electrocatalyst by preferential surface structure / shapes (cubic, tetrahedral, spherical, octahedral, etc).
This project will facilitate us in all fields of life: •
• • • •
• • •
Medicine: Researchers are developing customized nanoparticles the size of molecules that can deliver drugs directly to diseased cells in your body. When it's perfected, this method should greatly reduce the damage treatment such as chemotherapy does to a patient's healthy cells. Electronics: Nanotechnology holds answers for how we might increase the capabilities of electronics devices while we reduce their weight and power consumption. Space: It is helping in making space travelling more practical. Food: It has application in growing and packaging food. Fuel Cells: Nanotechnology is being used to reduce the cost of catalysts used in fuel cells to produce hydrogen ions from fuel such as methanol and to improve the efficiency of membrane used in fuel cells to separate hydrogen ions from other gasses such as oxygen. Solar Cells: Nanotechnology is helping to produce solar cells at low cost then other solar cells in use. Batteries: Nanotechnology is helping to produce batteries that will have more shelf life and they will be charged easily and quickly. Fuel: It will help to produce fuel from cheap raw material. 28
• • • •
Batter Air Quality: Specially designed nano particles will help in produce gasses from industrial and vehicles vapors. Water cleaning: Nanotechnology has enormous application in cleaning industrial waste water. Sensors: Nanotechnology has application to develop sensors that have application in many industries. Fabric: Nanotechnology have application in composite fabric industry.
In Addition to this, Nanotechnology may also have many other potential applications in various industries and their applications will increase with time.
Current state of the development in Pakistan: Pakistan
ISLAMABAD: Government is concentrating on establishing the Nano-technology laboratories with priority in Nano-biotechnology and establishing the synthesis and characterization techniques on the Nano-scale. Nano Science and Technology is newly growing and fast emerging field with unlimited industrial opportunities and helping to solve many problems of human welfare, may it be consumer goods or health care. All countries the world over, particularly the industrially advanced countries, are trying to reap benefits from Nanotechnology. Several developing countries are also actively and keenly pursuing to establish laboratories in this field. Talking to newsmen scientist and President National Academy of Young Scientists (NAYS) Dr Aftab Ahmed said nanotechnology is covering industries of all kinds such as Biotechnology products, auto industry, pharmaceuticals & drugs, Agriculture and Energy Sector. Realizing the importance of nano technology, he said, Pakistan has embarked on a programme of encouraging university laboratories and other research centres to work in the area of nano-technology relevant to their expertise. Aftab Ahmed said some laboratories have already hands on experience of research in nano-composites, nanomagnetics, nano-polymers and the techniques involved in the synthesis and characerisation of nano-materials thus produced. To give a more serious attention to the establishment of work on nano science and technology, Government has established recently a National Commission on NanoScience and Technology (NCNST) whose mandate is to help all universities and research centres in the country in the establishment of such laboratories. Its mandate is also to monitor the quality of research and the work done in such laboratories, he mentioned. He said some technologies are used only in specific applications, nanotechnology is not limited to certain fields and it is possible to be used in all aspects of sciences. In medicine, nanotechnology facilitates new ways of treatment through new 29
drug delivery systems. In medical imaging, nanotechnology based devices take more accurate images from cancerous tumors which might lead to a dramatic change in the treatment of cancer, he added. He elaborated one of the most important applications of nanotechnology is the environment where nanoparticles significantly increase the efficiency of groundwater pollutants filtration. Dr Aftab Ahmed said in the automotive sector, there is a growing demand for nanoscale technologies because of its high performance and efficiency, and in safety and emissions standards. Nanotechnology is currently providing solutions to unwanted heat transfer from the engine and fuel assembly components of vehicles; it would help to cool the interior parts of vehicles, allowing less work to be done by a cooling systems which is result consumes less fuel. He further said that applications of nanotechnology have the potential to change the entire agriculture sector and food industry chain from production to storage, processing, packaging, transportation, and even waste treatment. Nanotechnology has the potential to redesign the production cycle, including the restructuring process and conservation processes which redefine the food habits of people, he stated. In near future, nano structured catalysts will be available which will increase the efficiency of pesticides and herbicides, allowing lower doses to be used. President NAYS said Pakistan stands out well in setting up a nanotechnology center with the cooperation of Pakistan Council of Scientific and Industrial Research (PCSIR), where facilities are for industry to use as well as for conducting R&D that meets industry needs. Its nanotechnology lab facilities are utilized for the development, synthesis and characterization of 12 different nanocomposite coatings used in industries including Orthopedic implants & Surgical, Cutting Tool, Tool & Die and Textiles.This center focuses on nanocoating, nanomaterials and nanopowder and industry development.
Collaboration sought: Manufacturers of optical, magnetic, sensors, medical devices, catalysts (for using in batteries, fuel cells, gas diffusion electrodes, etc.), ceramic materials and/or pigments are sought in order to achieve technical cooperation and/or commercial with technical assistance agreements. In case of technical cooperation: adapting or developing the technology for the sector or market in which the company could be involved and under their requirements. In case of commercial agreement with technical assistance: training/assisting in set up processes, consulting in new processes, technical training.
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