Done by : Lee Jin Loong 3P3 09

 a field that takes a materials science-based approach to nanotechnology  material having at least one dimension 100 nanometres or less, up to10,000 could fit across a human hair. Nanomaterials can be nanoscale in one dimension (eg. surface films),two dimensions (eg. strands or fibres), or three dimensions (eg. particles). They can exist in single, fused, aggregated or agglomerated forms with spherical, tubular, and irregular shapes

 Engineered nanomaterials are materials designed at the molecular (nanometre) level to take advantage of their small size and novel properties which are generally not seen in their conventional, bulk counterparts  Two main reasons why materials at the nano scale can have different properties are increased relative surface area and new quantum effects  Nanomaterials have a much greater surface area to volume ratio than their conventional forms, which can lead to greater chemical reactivity and affect their strength  At the nano scale, quantum effects can become much more important in determining the materials properties and characteristics, leading to novel optical, electrical and magnetic behaviours.

 Nanomaterials (nanocrystalline materials) are materials possessing grain sizes on the order of a billionth of a meter  manifest extremely fascinating and useful properties and exploited for a variety of structural and non-structural applications  Since nanomaterials possess unique, beneficial chemical, physical, and mechanical properties, they can be used for a wide variety of applications. These applications include, but are not limited to, the following: ◦ Next-Generation Computer Chips ◦ Kinetic Energy (KE) Penetrators with Enhanced Lethality ◦ Better Insulation Materials ◦ Phosphors for High-Definition TV ◦ Tougher and Harder Cutting Tools

 Suspension (or colloid) of sub-micrometre-sized particles of gold in a fluid — usually water  Usually either an intense red colour (for particles less than 100 nm), or a dirty yellowish colour (for larger particles)  Properties and applications of colloidal gold nanoparticles depends upon shape. For example, rodlike particles have both transverse and longitudinal absorption peak, and anisotropy of the shape affects their self-assembly.

 Electron Microscopy ◦ Colloidal gold and various derivatives have long been among the most widely-used contrast agents for biological electron microscopy ◦ Colloidal gold particles can be attached to many traditional biological probes such as antibodies, lectins, superantigens, glycans, nucleic acids and receptors ◦ Particles of different sizes are easily distinguishable in electron micrographs, allowing simultaneous multiple- labelling experiments

 Health and medical applications ◦ successfully used as a therapy for rheumatoid arthritis in rats ◦ In a related study, the implantation of gold beads near arthritic hip joints in dogs has been found to relieve pain. ◦ An in vitro experiment has shown that the combination of microwave radiation and colloidal gold can destroy the beta-amyloid fibrils and plaque which are associated with Alzheimer's disease ◦ The possibilities for numerous similar radiative applications are also currently under exploration

 In cancer research, colloidal gold can be used to target tumors and provide detection using SERS (Surface Enhanced Raman Spectroscopy) in vivo  aman reporters were stabilized when the nanoparticles were encapsulated with a thiol-modified polyethylene glycol coat. This allows for compatibility and circulation in vivo  To specifically target tumor cells, the pegylated gold particles are conjugated with an antibody (or an antibody fragment such as scFv), against e.g. Epidermal growth factor receptor, which is sometimes overexpressed in cells of certain cancer types. Using SERS, these pegylated gold nanoparticles can then detect the location of the tumor

 nanoparticles of silver  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  Many different synthetic routes to silver nanoparticles. They can be divided into three broad categories: physical vapor deposition, ion implantation, or wet chemistry

 Over the last decades silver nanoparticles have found applications in catalysis, optics, electronics and other areas due to their unique size-dependent optical, electrical and magnetic properties  Currently most of the applications of silver nanoparticles are in antibacterial/antifungal agents in biotechnology and bioengineering, textile engineering, water treatment, and silver-based consumer products  There is also an effort to incorporate silver nanoparticles into a wide range of medical devices, including but not limited to ◦ bone cement ◦ surgical instruments ◦ surgical masks ◦ wound dressings ◦ treatment of HIV-1

 Samsung has created and marketed a material called Silver Nano, that includes silver nanoparticles on the surfaces of household appliances  Silver nanoparticles have been used as the cathode in a silver-oxide battery

 Fullerenes are a class of allotropes of carbon which conceptually are graphene sheets rolled into tubes or spheres. These include the carbon nanotubes (or silicon nanotubes) which are of interest both because of their mechanical strength and electrical properties  Fullerenes were under study for potential medicinal use: binding specific antibiotics to the structure of resistant bacteria and even target certain types of cancer cells such as melanoma

 Carbon nanotubes are molecular-scale tubes of graphitic carbon with outstanding properties. They are among the stiffest and strongest fibres known, and have remarkable electronic properties and many other unique characteristics. Commercial applications have been rather slow to develop, however, primarily because of the high production costs of the best quality nanotubes.  These cylindrical carbon molecules have novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science, as well as potential uses in architectural fields.  exhibit extraordinary strength and unique electrical properties, and are efficient thermal conductors.

 Nanotoxicology is the study of the toxicity of nanomaterials. Because of quantum size effects and large surface area, nanomaterials have unique properties compared with their larger counterparts  Nanotoxicology is a branch of bionanoscience which deals with the study and application of toxicity of nanomaterials  Nanotoxicological studies are intended to determine whether and to what extent these properties may pose a threat to the environment and to human beings. For instance, Diesel nanoparticles have been found to damage the cardiovascular system in a mouse model.

 Sub-specialty of particle toxicology. It addresses the toxicology of nanoparticles (particles <100 nm diameter) which appear to have toxicity effects that are unusual and not seen with larger particles  Typical nanoparticles that have been studied are titanium dioxide, alumina, zinc oxide, carbon black, and carbon nanotubes, and "nano-C 60 "  Seem to have some different properties from larger particles that are known to have pathogenic effects

 These differences seem to be a result of their size. Nanoparticles have much larger surface area to unit mass ratios which in some cases may lead to greater pro- inflammatory effects (in, for example, lung tissue). In addition  nanoparticles seem to be able to translocate from their site of deposition to distant sites such as the blood and the brain.  resulted in a sea-change in how particle toxicology is viewed- instead of being confined to the lungs, nanoparticle toxicologists study the brain, blood, liver, skin and gut. Nanotoxicology has revolutionised particle toxicology and rejuvenated it.

  n_sheets/general_information_sheets/nis_nanomat erials_pdf.pdf   