Gold nano particle probes possess several properties that make them ideal for diagnostic applications:
Allows increased sensitivity by several orders of magnitude; light scattered from one nano particle is equivalent to the light emitted from 5x105 (500,000) fluorophores. Tests that employ gold nano particles functionalized with antibodies, for example, are 2-3 orders of magnitude more sensitive than ELISA-based methods.
Enables high-specificity for both nucleic acid and protein detection. For nucleic acid detection, single-base pair specificity is achieved due to assay reaction kinetics where gold nano particle probes, comprised of target-specific oligonucleotides, permit hybridization to target DNA over a very narrow temperature range.
Reduces background noise (i.e. signal-to-signal) due to minimal non-specific binding of the gold nanoparticle probes, which in turn, create an enhanced assay signal.Requires little or no inventory control. The nanoparticle probes are extremely stable, have a long shelf-life, and are non-toxic.
Applications:
The range of applications for gold nano particles is growing rapidly and includes:
- Electronics - Gold nano particles are designed for use as conductors from printable inks to electronic chips.1 As the world of electronics become smaller, nano particles are important components in the chip design. Nanoscale gold nano particles are being used to connect resistors, conductors, and other elements of an electronic chip.
- Photodynamic Therapy - Near-IR absorbing gold nano particles (including gold nanoshells and nanorods) produce heat when excited by light at wavelengths from 700 to 800 nm. This enables these nanoparticles to eradicate targeted tumors.2 When light is applied to a tumor containing gold nanoparticles, the particles rapidly heat up, killing tumor cells in a treatment also known as hyperthermia therapy.
- Therapeutic Agent Delivery - Therapeutic agents can also be coated onto the surface of gold nanoparticles.3 The large surface area-to-volume ratio of gold nanoparticles enables their surface to be coated with hundreds of molecules (including therapeutics, targeting agents, and anti-fouling polymers).
- Sensors - Gold nanoparticles are used in a variety of sensors.
- Probes - Gold nano particles also scatter light and can produce an array of interesting colors under dark-field microscopy. The scattered colors of gold nano particles are currently used for biological imaging applications.5 Also, gold nano particles are relatively dense, making them useful as probes for transmission electron microscopy.
- Diagnostics - Gold nano particles are also used to detect biomarkers in the diagnosis of heart diseases, cancers, and infectious agents.6 They are also common in lateral flow immunoassays, a common household example being the home pregnancy test.
- Catalysis - Gold nano particles are used as catalysts in a number of chemical reactions.7 The surface of a gold nano particle can be used for selective oxidation or in certain cases the surface can reduce a reaction (nitrogen oxides). Gold nano particles are being developed for fuel cell applications. These technologies would be useful in the automotive and display industry.