Platinum nanoparticles
Encyclopedia
Platinum nanoparticles are usually in the form of a suspension or colloid
of sub-micrometre
-sized particles of platinum in a fluid
, usually water
. A colloid is technically defined as particles which remain suspended without forming an ionic, or dissolved solution. The broader commercial definition of "colloidal platinum" includes products that contain various concentrations of ionic platinum, platinum colloids, ionic platinum compounds or platinum nanoparticles in purified water.
The platinum
nanoparticle
sizes range between 2-3 nanometres (nm). Trillions of platinum nanoparticles are suspended in the brownish red or black colored colloidal solution. Nanoparticles come in wide variety of shapes including spheres, rods, cubes, and caps.
Due to the antioxidant
properties of the platinum nanoparticles, they are the subject of substantial research with applications in a wide variety of areas, including nanotechnology
, medicine and the synthesis of novel materials with unique properties.
of hexachloroplatinate
. After dissolving hexachloroplatinate, the solution
is rapidly stirred while a reducing agent
is added. This causes platinum ions to be reduced to neutral platinum atoms. As more and more of these platinum atoms form, the solution becomes supersaturated and platinum gradually starts to precipitate in the form of sub-nanometre
particles. The rest of the platinum atoms that form stick to the existing particles, and, if the solution is stirred vigorously enough, the particles will be fairly uniform in size. Various procedures employed to attain platinum nanoparticles include heating, reflux
, cooling, stirring, filtration and filling, examinations & tests and packaging. To prevent the particles from aggregating, some sort of stabilizing agent or stabilizer that sticks to the nanoparticle surface is usually added. They can be functionalized with various organic
ligands to create organic-inorganic hybrids with advanced functionality.
.
Nanoparticles may present possible safety issues both medically and environmentally. 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. In particular, inhaled nanoparticles can pose health risks, and may cause inflammation and disease in the lung. They are able to pass through cell membranes in organisms and their interactions with biological systems are relatively unknown. However, free nanoparticles in the environment quickly tend to agglomerate
and thus leave the nano-regime, and nature itself presents many nanoparticles to which organisms on earth may have evolved immunity (such as salt
particulates from ocean aerosols, terpenes from plants, or dust from volcanic eruptions).
Colloid
A colloid is a substance microscopically dispersed evenly throughout another substance.A colloidal system consists of two separate phases: a dispersed phase and a continuous phase . A colloidal system may be solid, liquid, or gaseous.Many familiar substances are colloids, as shown in the chart below...
of sub-micrometre
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
-sized particles of platinum in a fluid
Fluid
In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
, usually water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
. A colloid is technically defined as particles which remain suspended without forming an ionic, or dissolved solution. The broader commercial definition of "colloidal platinum" includes products that contain various concentrations of ionic platinum, platinum colloids, ionic platinum compounds or platinum nanoparticles in purified water.
The platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
nanoparticle
Nanoparticle
In nanotechnology, a particle is defined as a small object that behaves as a whole unit in terms of its transport and properties. Particles are further classified according to size : in terms of diameter, coarse particles cover a range between 10,000 and 2,500 nanometers. Fine particles are sized...
sizes range between 2-3 nanometres (nm). Trillions of platinum nanoparticles are suspended in the brownish red or black colored colloidal solution. Nanoparticles come in wide variety of shapes including spheres, rods, cubes, and caps.
Due to the antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
properties of the platinum nanoparticles, they are the subject of substantial research with applications in a wide variety of areas, including nanotechnology
Nanotechnology
Nanotechnology is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures possessing at least one dimension sized from 1 to 100 nanometres...
, medicine and the synthesis of novel materials with unique properties.
Synthesis
Platinum nanoparticles are fabricated by reductionRedox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....
of hexachloroplatinate
Hexachloroplatinate
The hexachloroplatinate anion has the chemical formula [PtCl6]2-, containing platinum and chloride ions. Compounds with the hexachloroplatinate anion are not very soluble.Chemical compounds containing the hexachloroplatinate anion include:...
. After dissolving hexachloroplatinate, the solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
is rapidly stirred while a reducing agent
Reducing agent
A reducing agent is the element or compound in a reduction-oxidation reaction that donates an electron to another species; however, since the reducer loses an electron we say it is "oxidized"...
is added. This causes platinum ions to be reduced to neutral platinum atoms. As more and more of these platinum atoms form, the solution becomes supersaturated and platinum gradually starts to precipitate in the form of sub-nanometre
Nanometre
A nanometre is a unit of length in the metric system, equal to one billionth of a metre. The name combines the SI prefix nano- with the parent unit name metre .The nanometre is often used to express dimensions on the atomic scale: the diameter...
particles. The rest of the platinum atoms that form stick to the existing particles, and, if the solution is stirred vigorously enough, the particles will be fairly uniform in size. Various procedures employed to attain platinum nanoparticles include heating, reflux
Reflux
Reflux is a technique involving the condensation of vapors and the return of this condensate to the system from which it originated. It is used in industrial and laboratory distillations...
, cooling, stirring, filtration and filling, examinations & tests and packaging. To prevent the particles from aggregating, some sort of stabilizing agent or stabilizer that sticks to the nanoparticle surface is usually added. They can be functionalized with various organic
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
ligands to create organic-inorganic hybrids with advanced functionality.
Biological effects
Research by Yusei Miyamoto at University of Tokyo, Japan, resulted in the use of platinum nanoparticles of the size 2-3 nm to increase the lifespan of the roundworm Caenorhabditis elegansCaenorhabditis elegans
Caenorhabditis elegans is a free-living, transparent nematode , about 1 mm in length, which lives in temperate soil environments. Research into the molecular and developmental biology of C. elegans was begun in 1974 by Sydney Brenner and it has since been used extensively as a model...
.
Nanoparticles may present possible safety issues both medically and environmentally. 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. In particular, inhaled nanoparticles can pose health risks, and may cause inflammation and disease in the lung. They are able to pass through cell membranes in organisms and their interactions with biological systems are relatively unknown. However, free nanoparticles in the environment quickly tend to agglomerate
Agglomerate
Agglomerates are coarse accumulations of large blocks of volcanic material that contain at least 75% bombs...
and thus leave the nano-regime, and nature itself presents many nanoparticles to which organisms on earth may have evolved immunity (such as salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
particulates from ocean aerosols, terpenes from plants, or dust from volcanic eruptions).
See also
- Colloidal goldColloidal goldColloidal gold is a suspension of sub-micrometre-sized particles of gold in a fluid — usually water. The liquid is usually either an intense red colour , or a dirty yellowish colour ....
- Nanoparticles
- Nanomaterial based catalystNanomaterial based catalystNanomaterial-based catalysts are usually heterogeneous catalysts broken up into nanoparticles in order to speed up the catalytic process. The extremely small size of the particles maximizes the surface area exposed to the reactant, allowing more reactions to occur at the same time, thus speeding...
- NanotechnologyNanotechnologyNanotechnology is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures possessing at least one dimension sized from 1 to 100 nanometres...