Biological applications

Companies are working with nanoparticles based on other materials as genetic or biological probes in drug discovery, screening, diagnostics and cure. Some others are looking at drug delivery. One of the most straightforward approaches is nanocrystalline drugs.
NanoSystems, owned by Irish drug company Elan,24 uses its technology for drugs that have poor water solubility, stabilizing the drug nanoparticles with polymers on their surfaces. Nanosphere (USA) has a related technology--applicable, but not limited to,controlled-release drugs--that applies polymer, ceramic, metal, or biomaterial "nanosphere" coatings on particles.
Quantum Dot,25 California (USA) makes semiconductor-based nanoparticles.
The luminescent dots have hydrophillic surfaces so they can work in aqueous solution .They can be used with almost any optical detection method and will compete with traditional methods such as dyes. The quantum dots can be attached to DNA, to proteins, to various sorts of biological affinity molecules such as antibodies, or put within different sorts of microscopic carrier particles for colorimetric bar coding purposes.
Already on the market are 1.4-nm derivatized or silver-coated gold particles that are produced by Nanoprobes, New York (USA). Its nanoparticles can be used as chemically specific labeling reagents and immunoassay probes in light and electron microscopy, molecular biology, and cellular studies. Solaronix (Switzerland) has been producing and have commercialised TiO2 nanoparticle based solar cells since a few years now.26 And magnetic particles, such as those made of iron and activated carbon by San Diego-based FeRx,27 can be carriers for targeted drug delivery. Metalor (Switzerland), as many other companies worldwide, supply wide ranging gold, silver, and other metal alloy colloidal formulations of different sizes.
Mach 1, based in Pennsylnavia (USA) plans to produce magnetic iron oxide for biological applications. The company has been making 3-nm iron oxide since 1992 and selling it for catalyst and solid rocket propellant applications. Volumes are still small if measured in tens of thousands of dollars and bordering between pilot and semicommercial scale.