Gold nanoparticles (AuNPs) ranging from 2-200nm in diameter find applications in diverse fields. They show excellent biocompatibility and attractive physicochemical properties. AuNPs, as aggregates, is shown to be highly sensitive colloidal biosensors. Poly (ethylene) glycol (PEG) surface coating on gold nanoparticles helps in the reduction of protein adsorption, reduces nonspecific interactions with cells and greatly improves the pharmokinetics of these nanoparticles and disables aggregation of the nanoparticles. PEG layer density depends inversely on the AuNP curvature. Denser coating was possible on smaller AuNPs. AuNPs coated with PEG 5000 exhibited highest colloidal stability. Amine functionalized GNPs which has Poly Ethylene Glycol (PEG) as the ligand or carrier molecule forms a conjugate with siRNA and is extremely useful in RNAi technology. Since it adheres to cell membranes, it may find use in cellular and intracellular targeting in targeted drug delivery applications and also used in biodistribution studies.

功能化颗粒已广泛用于研究纳米颗粒的细胞摄取和靶向药物递送。

Several other specific applications have been listed below:

• Since they adhere to cell membranes, AuNPs are used in cellular and intracellular targeting in targeted drug delivery applications and can also be used in biodistribution studies
• AuNPs may also be used in photothermal therapy and radiotherapy.
• AuNPs ranging from 10 to 250 nm, were studied to have been absorbed primarily by liver and spleen, when injected intravenously in rats.
• They may also be used in carrying siRNA which acts against human prostate carcinoma cells by inhibiting a specific cancer gene.