Nanotechnology has taken Researchers and Engineers alike by storm in recent times, and innovations in this field bring drastic improvements to our lives. For instance, the use of nanotechnology in targeted drug delivery systems instead of the traditional sustained release capsule increases the precision of the system by utilising its nanoscale properties. This article will cover a brief overview of Nanotechnology focusing mainly on the history, synthesis and classification.
The term “Nano” comes from the Greek word nânos or nánnos, which means “Dwarf”. In Science, using nano as a prefix means “one-billionth” or 10 with a negative power of 9. In simple terms, Nanotechnology deals with particles measuring between 1 to 100 nanometers. Most people tend to mix up Nanotechnology with Nanoscience but even though these words look similar, Nanoscience deals with the structures and molecules at the nanoscale and mostly deals with theory, while Nanotechnology is more application oriented and uses the known knowledge about nanoparticles to create, design and utilise them in devices and systems.
There have been several instances throughout history where Scientists have indirectly referred to nanotechnology, but the major step towards it was taken on December 29, 1959 when American physicist and Nobel prize winner Richard Feynman gave his lecture at the American Physical Society meeting held at the California Institute of Technology titled “There's Plenty of Room at the Bottom: An Invitation to Enter a New Field of Physics” in which he focused on the direct manipulation of individual atoms over the bulk methods to increase the precision in Synthetic Chemistry which involves creating new chemical compounds through artificially executing controlled chemical reactions often combining simpler materials to form complex ones. This lecture is often referred to as the inspiration for the field of Nanotechnology.
Now, there are many techniques used for making these nanomaterials, but these techniques can be largely classified into two categories, namely: the Top-Down Method, the Bottom-Up Method. The Top-Down Method includes techniques that breaks down large bulk materials into smaller nanostructures, it includes processes like mechanical milling, laser ablation, etching, sputtering, etc. In contrast, the Bottom-Up Method includes techniques that assemble atoms and molecules into organised nanostructures, techniques like the sol-gel methods, chemical vapor deposition(CVD) and self assembly processes come under this category.
Nanomaterials can be classified using various criteria, but here we will be classifying them using 3 of them: Origin, Dimensionality and Composition.
Nanomaterials can be classified as natural and artificial based on their origin; Natural being the materials found in nature that have nanostructures, examples include DNA, viruses, etc. Artificial nanomaterials are made by humans to have specific properties. Carbon nanotubes and quantum dots are some examples.
When we classify nanomaterials by dimensionality, we simply have to look at the number of dimensions that are larger than 100nm. “0D” simply means that there are no dimensions greater than 100nm; for example, quantum dots and nanospheres. Similarly, for “1D” we have 1 dimension greater than 100nm with nanotubes and nanowires as examples and 2 greater dimensions for “2D” with graphene and black phosphorus as examples. Now, for “3D” nanomaterials all 3 dimensions are greater than 100nm but these structures are made from the assembly of individual nano-units with fullerenes and dendrimers as examples.
The composition of materials present in the nanomaterials defines this classification. Nanomaterials can be mainly classified into Organic, Inorganic(metal-based), Carbon-based and composites with respect to their composition. Organic Nanomaterials are made of organic molecules like proteins, polymers; dendrimers and liposomes are some examples. Inorganic Nanomaterials are made of materials that have absence of carbon atoms like metals and metal oxides, nanoparticles of metals like gold and silver can be considered as examples. Carbon-based Nanomaterials are mainly made of carbon atoms with carbon nanotubes, graphene, and fullerenes being some of the primary examples. Composites, in simple terms, are made from the combination of different types of nanomaterials like aluminium reinforced with carbon nanotubes and Graphene/Polymer Composites.
We have barely scratched the surface of nanotechnology and there is currently a lot of work and time put in by scientists and engineers towards nanotechnology that would help us acquire more insights into nanomaterials which in turn will help us customise them for our applications. Nanotechnology has immense potential for innovations that promise to transform our lives for the better in the near future.
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