Gold nanoparticles have a high surface reactivity, biocompatible properties, used for in vivo molecular imaging, therapeutic applications, cancer detection, as in vivo sensors, photoactive agents for optical imaging, drug carriers and contrast enhancers in computer tomography and X-ray absorbers in cancer therapy. This is because high surface area and size relationships of nanoparticles to cells, which helps to target individual cells for diagnostic imaging or therapy. In spite of this, scientists have a challenge in that there are problems in making nontoxic gold nanoparticle constructs. Gold nanoparticles used to detect and treat cancer and other diseases can not remain in a stable, nontoxic form that can be injected into a patient. But a plant extract has been used to create a new type of gold nanoparticle that is stable and nontoxic and can be administered orally or injected. Georgia TechResearchers from the University of Missouri have developed a biocompatible and environmentally friendly method of obtaining gold nanoparticles. The research team was successful at identifying a natural phytochemical that would break down gold compounds into gold nanoparticles. The researchers have discovered how to produce and stabilize gold nanoparticles the "green" way with soybeans. The process involves bathing the gold salts in water and soybeans. The water draws a phytochemical out of the soybean that enables the breakdown of the gold into gold nanoparticles.
Researchers have tested plant extracts for their ability as nontoxic vehicles to stabilize and deliver nanoparticles for in vivo nanomedicinal applications. One such plant extract is gum arabic, a substance taken from species of the acacia tree, which is already used to stabilize everyday foods such as yogurt. Gum arabic has unique structural features, including a highly branched polysaccharide structure consisting of a complex mixture of potassium, calcium and magnesium salts derived from arabic acid. The scientists found that gum arabic could be used to absorb and assimilate metals and create a "coating" that makes gold nanoparticles stable and nontoxic.

According to researchers the excellent in vivo stability profiles of such gold nanoconstructs will open up new pathways for the intratumoral delivery of gold nanoparticles in diagnostic imaging and therapeutic applications for cancer and can be administered either orally or through intravenous injection within the biological system. This discovery will initiate a new generation of biocompatible gold nanoparticles