Gold nanoparticles

Gold nanoparticles (AuNPs) ranging from 2-200nm in diameter find applications in diverse fields. They show excellent biocompatibility and attractive physicochemical properties. AuNPs are shown to be highly sensitive colloidal biosensors. The poly (ethylene) glycol (PEG) 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. AuNPs coated with PEG 5000 exhibited the highest colloidal stability. The methyl group, being hydrophobic acts as a protecting shield between the gold nanoparticles and the hydrophilic outer PEG coating and also leads to a further reduction of protein adsorption and macrophage uptake by the AuNPs.

Several other specific applications have been listed below:

• Since they adhere to cell membranes, AuNPs may find use in cellular and intracellular targeting in targeted drug delivery applications and may also 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.Whereas, 10 nm nanoparticles were distributed more broadly into various organs.

Functionalized Particles have been extensively used to study cellular uptake of nanoparticles and targeted drug delivery.

PEG decreases the cytotoxicity and increases efficiency of GNPs in targeted drug delivery. PEG increases the stability of the nanoparticles and prevents agglomeration. Forms complexes easily with dyes and thiol ligands.