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What are Nanoparticles?

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Also known as the zero-dimensional nanomaterials, nanoparticles are particles whose dimensions are below 100nm. These microscopic particles have unique properties that make them suitable for immense chemical reactivity, bio mobility, and energy absorption. Nanoparticles naturally occur in the environment but also are artificially synthesized. They are applied extensively in the development of modern medicine. It includes sophisticated processes like contrast agents in medical imaging and gene transfer into a cell. Engineering, catalysis, and environmental remediation are also areas where nanotechnology gets used widely. One of the biggest challenges is the toxicity which the nanoparticles pose to society and the environment. Nevertheless, nanoparticles are a boon to the modern world. 


Size of the Nanoparticles

Nanoparticles are invisible to the human eye. They exhibit significant chemical and physical changes in the larger materials. As their size approaches that of the atomic particles, their properties get modified even more. Each nanoparticle has a few thousand atoms. As the particles reduce in size more and more, their surface area to volume ratio increases, resulting in the surface atoms dominating the material. Moreover, these nanoparticles are enormously small and are able to confine the electrons present in them and produce quantum effects. The surface area of the nanoparticles is even larger than that of powders, plates, or sheets. 


Physicochemical Properties of Nanoparticles

Mechanical strength, large surface area, optical and chemical reactivity are properties that make the nanoparticles unique. However, there are several other physicochemical properties:

  1. Noble metal nanoparticles are size-dependent in their optical properties. They have a UV-visible spectrum band that is not present in bulk metals. It appears when excited by the Localized Surface Plasmon Resonance (LSPR) and results in wavelength selection absorption and molar excitation. Ray light scatters along with enhancing electromagnetic fields. Hence the optical and electronic properties are interdependent.

  2. The nanoparticles work best when their diameter is less than the critical value. The magnetic properties of the particles are very effective below 10-20 nm. It makes them useful for several applications.

  3. When compared to microparticles, nanoparticles show dissimilar mechanical properties. The mechanical parameters such as hardness, elastic modulus, stress and strain, adhesion, and friction are determined. They are used to analyze if the nanoparticles have a usage in nanomanufacturing and nanofabrication. 

  4. The nanofluids are used in specialized heat transfer phenomenon's. The thermal conductivity of these fluids is more enhanced than that of conventional fluids. The metal nanoparticles have conductivities 1000 times greater than the fluids. 


Uses and Applications of Nanoparticles

Nanoparticles are produced by engineering methods or through combustion techniques. Healthcare, cosmetics, environmental preservation, and air purification are processes that involve nanoparticle technology. These particles transport chemotherapeutic drugs across the human body for the treatment of cancer. They can transfer even to the regions where the arteries are damaged. Aerospace engineers use carbon nanotubes for the morphing of aircraft wings. Zinc oxide nanowires applied in the solar cells help in environmental preservation. The nanoparticles hence have several other applications. 


Questions and Answers

1. Compare the Size of the Nanoparticles with Other Particle Types.

Answer - The following table shows the comparison:

           Type of Particle

  Size Range (Diameter)

   Small molecules and atoms

                    0.1nm

         Nanoparticles

                 1-100nm

  Particulate Matter (PM2.5)

                 100-2500nm

  Coarse particles (PM10)

                 2500-10,000nm

  Thickness of Paper

                  100,000nm


2. Give Some Nanoparticles Examples.

Answer- There are several kinds of nanoparticles based on their morphology. For example, some nanoparticles get prepared from the precursors of metals. These metal nanoparticles get synthesized by chemical, electrochemical, or photochemical methods. They have high surface energy and hence can absorb small molecules. In scanning electron microscopes, gold nanoparticles are used for analyzing a sample. Carbon nanoparticles are other types that have fullerenes and graphene sheets rolled into carbon nanotubes. These nanoparticles are famous for their high strength and electrical conductivity. Semiconductor nanoparticles have properties between metals and nonmetals. Polymeric nanoparticles are organic-based. These structures are either Nano capsules or Nano spheres.  Their release can be controlled and hence used in the protection of drug molecules. The ceramic nanoparticles arise from the oxides, carbonates, carbides, and phosphates which are inorganic in nature. They are mainly used as drug delivery agents.

FAQ (Frequently Asked Questions)

1. What is Nanotechnology?

Answer. Nanotechnology is the study, analysis and application of nanoparticles whose properties are manipulated by bringing changes into their sizes. It is basically the application of extremely small things called nanoparticles that can be used across all other scientific fields such as chemistry, biology, physics and especially in material science. The particles which are studied are within 1 to a 100 nm. The foundation of the field was laid down by its father, Dr. Richard Feynman. The concept was first explained by him in a lecture called “There’s plenty of room at the Bottom”  which was held at the American Physical Society at the California Institute of Technology. 


Feynman explained a process where scientists would be able to control every single atom and molecule. The term nanotechnology was coined by Professor Norio Taniguchi, during his exploration of ultraprecision machining. 

2. Are Nanoparticles Toxic?

Answer- Nanoparticles can enter the human body through inhalation, ingestion or even skin contact. Nanoparticles released into the environment through construction works are extremely harmful. A range of pathological problems like cardiovascular, respiratory, lymphatic, autoimmune diseases and even the degeneration of the nervous system can take place. Exposure to these particles for many years can even lead to the development of cancer cells in the body. The toxicity of the particles are different based on their reactivity, retention time and distribution in the human body. Studies are going on to analyse these toxic effects and prevent the nanoparticle intoxication and to develop tailor made health treatments.