Platinum nanoparticles

Platinum nanoparticles are usually in the form of a suspension or colloid[1] of submicrometre-size particles of platinum in a fluid, usually water. A colloid is technically defined as a stable dispersion of particles in a fluid medium (liquid or gas).

Platinum nanoparticles can be made with sizes between about 2 and 20 nanometres (nm), depending on reaction conditions. Trillions of platinum nanoparticles are suspended in the colloidal solution of brownish-red or black color. Nanoparticles come in wide variety of shapes including spheres, rods, cubes, [2] and tetrahedra.[3]

Due to the antioxidant properties of the platinum nanoparticles, they are the subject of substantial research, with potential applications in a wide variety of areas, including nanotechnology, catalysis, medicine, and the synthesis of novel materials with unique properties.

Synthesis

Platinum nanoparticles[4] are made by reduction of hexachloroplatinate. A solution is rapidly stirred while a reducing agent such as hydrogen gas is added, causing platinum ions to be reduced to neutral platinum atoms. As more and more of these platinum atoms form, the solution quickly becomes supersaturated and platinum starts to precipitate in the form of sub-nanometre particles. As the reaction proceeds, platinum atoms are added to these nuclei, which grow in size. If the solution is stirred vigorously enough, the particles will be fairly uniform in size and shape. To prevent the particles from aggregating, some sort of stabilizing agent or stabilizer that sticks to the nanoparticle surface is usually added, such as sodium polyacrylate. They can be functionalized with various organic ligands to create organic-inorganic hybrid materials with advanced functionality.

Biological effects

Research by Yusei Miyamoto at University of Tokyo, Japan,[5] resulted in the use of platinum nanoparticles[6] of the size 2-3 nm to increase the lifespan of the roundworm Caenorhabditis elegans.[7]

Nanoparticles may present possible safety issues both medically and environmentally.[8] Most of these issues usually arise due to the high surface-to-volume ratio, which can make the particles of some metals very reactive or catalytic.[9] In particular, inhaled nanoparticles can pose health risks,[10] and may cause inflammation and disease in the lung.[11] They are able to pass through cell membranes in organisms and their interactions with biological systems are relatively unknown.

See also

References

  1. ↑ Conductive Polymer / Solvent Systems: Solutions or Dispersions?, Bernhard Wessling, 1996
  2. ↑ PJF Harris (1986). "Sulphur-induced faceting of platinum catalyst particles.". Nature 323 (6091): 792–94. doi:10.1038/323792a0.
  3. ↑ TS Ahmadi, ZL Wang, TC Green, A Henglein and MA El-Sayed (1996) Shape controlled synthesis of colloidal platinum nanoparticles. Science 272, 1924-1926.
  4. ↑ Creation of platinum nanoparticles (pdf)
  5. ↑ Graduate school of Frontier Sciences, University of Tokyo, Japan, http://www.ib.k.u-tokyo.ac.jp/ib-E/index.html
  6. ↑ Room temperature synthesis of colloidal platinum nanoparticles (pdf)
  7. ↑ Kim J, Takahashi M, Shimizu T et al. (June 2008). "Effects of a potent antioxidant, platinum nanoparticle, on the lifespan of Caenorhabditis elegans". Mech. Ageing Dev. 129 (6): 322–31. doi:10.1016/j.mad.2008.02.011. PMID 18400258.
  8. ↑ De Jong WH, Borm PJ (2008). "Drug delivery and nanoparticles:applications and hazards". Int J Nanomedicine 3 (2): 133–49. doi:10.2147/ijn.s596. PMC 2527668. PMID 18686775.
  9. ↑ Oberdörster G, Oberdörster E, Oberdörster J (July 2005). "Nanotoxicology: an emerging discipline evolving from studies of ultrafine particles". Environ. Health Perspect. 113 (7): 823–39. doi:10.1289/ehp.7339. PMC 1257642. PMID 16002369.
  10. ↑ Borm PJ, Kreyling W (May 2004). "Toxicological hazards of inhaled nanoparticles--potential implications for drug delivery". J Nanosci Nanotechnol 4 (5): 521–31. doi:10.1166/jnn.2004.081. PMID 15503438.
  11. ↑ Medina C, Santos-Martinez MJ, Radomski A, Corrigan OI, Radomski MW (March 2007). "Nanoparticles: pharmacological and toxicological significance". Br. J. Pharmacol. 150 (5): 552–8. doi:10.1038/sj.bjp.0707130. PMC 2189773. PMID 17245366.