Rheumatoid Arthritis Support

Colloidal gold has been successfully used as a therapy for rheumatoid arthritis in rats. In a related study, the implantation of gold beads near arthritic hip joints in dogs has been found to relieve pain.

An ''in vitro'' experiment has shown that the combination of microwave radiation and colloidal gold can destroy the beta-amyloid fibrils and plaque which are associated with Alzheimer's disease. The possibilities for numerous similar radiative applications are also currently under exploration.

Gold nanoparticles are being investigated as carriers for drugs such as Paclitaxel. The administration of hydrophobic drugs require molecular encapsulation and it is found that nanosized particles are particularly efficient in evading the reticuloendothelial system.

In cancer research, colloidal gold can be used to target tumors and provide detection using SERS (Surface Enhanced Raman Spectroscopy) ''in vivo''. These gold nanoparticles are surrounded with Raman reporters which provide light emission that is over 200 times brighter than quantum dots. It was found that the Raman reporters were stabilized when the nanoparticles were encapsulated with a thiol-modified polyethylene glycol coat. This allows for compatibility and circulation ''in vivo''. To specifically target tumor cells, the pegylated gold particles are conjugated with an antibody (or an antibody fragment such as scFv), against e.g. Epidermal growth factor receptor, which is sometimes overexpressed in cells of certain cancer types. Using SERS, these pegylated gold nanoparticles can then detect the location of the tumor.

Gold nanorods are being investigated as photothermal agents for in-vivo applications. Gold nanorods are rod shaped gold nanoparticles whose aspect ratios tune the surface plasmon resonance (SPR) band from the visible to near infrared wavelength. The total extinction of light at the SPR is made up of both absorption and scattering. For the smaller axial diameter nanorods (~10& nm), absorption dominates, whereas for the larger axial diameter nanorods (>35& nm), scattering can dominate. Consequently, for in-vivo applications, small diameter gold nanorods are being used as photothermal converters of near infrared light due to their high absorption cross sections. Since near infrared light transmits readily through human skin and tissue, these nanorods can be used as ablation components for cancer, and other targets. When coated with polymers, gold nanorods have been known to circulate in-vivo for greater than 15 hours half life.


Adapted from the Wikipedia article Colloidal gold, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki