The word “ nano” is from the Greek word Nanos meaning dwarf. Nanoscience is preparing nano-sized materials, controlling the properties of nano-sized materials. Nanotechnology is the manipulation, production, or the use of materials ranging in size of nanoscale that is between 1nm to 100nm. Scientists studying and working with nanoparticles for along time. Nanoparticles can be synthesized depending on their use.
Nanotechnology in India
- IIT Mumbai is the premier organization in the field of nanotechnology. Starting 2001 the government of India launched the Nano Science & Technology Initiative (NSTI).
- Then in 2007 the Nanoscience & technology mission 2007 was initiated with an allocation of Rs. 100 crores for five years.
Novel properties of nanomaterials
- Material reduced to the nanoscale can show very different properties when compared to macroscale.
- Opaque substance become transparent (copper)
- Inert substance become catalysts (platinum)
- Solid substances become liquids at room temperatures (aluminum)
- Insulator becomes conductor (silicon)
Synthesis of nanoparticle(NP)
It can be done via biological, chemical, physical. Today we are going to learn about the biological method. The synthesis of nanoparticles using biological entities has great interest. They are divided into 3 groups as follows:-
- Use of microorganism
- Use of plant extracts or enzymes
- Use of templates
Synthesis using microorganism:-
Here we will see some of the organisms used in the biosynthesis of nanomaterial.
Use of bacteria:-
Pseudomonas stutzeri AG259 isolated from silver mines has been shown to produce silver NP. The synthesis of magnetic NP has been reported by magnetotactic bacteria such as Magnetospirillum magneticum produces magnetic (Fe3O4) NP’s in chains & some produce greigite (Fe3S4) nanoparticles while some produce both NPs.
Lactobacillus strains found in buttermilk assisted the growth of microscopic gold, silver & gold-silver. Recently bacterial cell supernatant Pseudomonas aeruginosa was used for the reduction of gold ions resulting in extracellular biosynthesis of gold NPs.
Use of actinomycetes
It has been observed that the extremophilic actinomycetes, Thermomonospora spp when exposed to the gold ions reduced the metal ions extracellularly, yielding gold NP with a much-improved polydispersity. It is believed that the reduction of metal ions & stabilization of the gold NPs occurs by an enzymatic process. The metal ions were not toxic to the cell, which are producing them.
Use of yeast:-
Candida glabrata & Schizosaccharomyces pombe were used for the first time in the biosynthesis of cadmium sulfide nanocrystal. These nanocrystals were produced using cadmium salts. A study conducted to improve the number of semiconductor CdS nanocrystals production that was achieved by using Schizosaccharomyces pombe cells.
Use of fungi:-
Nanoparticles formation invitro approach was followed where species-specific NADPH dependent reductase, released by the Fusarium oxysporum was successfully carried out the reduction of AlCl4 ions to gold particles. This has opened up a novel fungal / enzyme-based in vitro approach for Nanomaterials synthesis. The acidophilic fungus Verticillium sp has the capability of producing gold as well as silver NPs using fungi.
Use of plant
Quantum dots have huge applications in nanotechnology and plant have been observed to be of a good source. One of the investigations with alfalfa documents the feasibility for the synthesis of quantum dots by the living plants. Transmission electron microscope or scanning electron microscope are used for the analysis of the atoms inside the plant tissue underwent nucleation formation of nanoparticles.
Example:- Use of Emblica Officinalis fruit extract as a reducing agent, the extracellular synthesis of highly stable Ag & Au nanoparticles has been achieved. It has been shown by the rapid synthesis of stable gold nano triangles at high concentrations using tamarind leaf extract as a reducing agent.
Application of nanoparticles
Development of nano-devices using biological materials & there is a wide range as follows:
- Cancer therapy for targeting, to enhance uptake of anti-tumor agent.
- Improved imaging of the human body
- Nano tracking may be able to detect tumors that are a few cells in size.
- Allow the mimicking of natural biological processes e.g repair of damaged tissues.
- Biosensors have been improved by using nanomaterials.
- Gold nano triangles with unique & highly anisotopic planer shapes might find application in optical sensing.
- It has an application in antibacterial effects.
- Silver NPs have a great number of applications such as in non-linear optics, bio labeling, intercalation materials for electrical batteries.
- Biominerals formulation using bacteria which can function of quantum semiconductor crystallite.
- NPS from magnetotactic bacteria has been used as a carrier for immobilization of bioactive substances such as enzyme, antibodies, DNA & RNA.