General descriptionGold nanoparticles (AuNPs) ranging from 2-200nm in diameter find applications in diverse fields. They show excellent biocompatibility and attractive physicochemical properties. Poly (ethylene) glycol (PEG) surface coatings on gold nanoparticles help in the reduction of protein adsorption, reduce nonspecific interactions with cells and greatly improve the pharmokinetics of these nanoparticles and reduce aggregation of the nanoparticles. PEG layer density depends inversely on the AuNP curvature. Denser coating was possible on smaller AuNPs. Carboxylic acid functionalized GNPs form conjugates with various protein molecules due to the electrostatic attraction between the negatively charged carboxylate groups and positively charged amino groups of protein. 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.
Application
Functionalized Particles have been extensively used to study cellular uptake of nanoparticles and targeted drug delivery.
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 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.Whereas, 10 nm nanoparticles were distributed more broadly into various organs.
- Carboxylic acid end-groups bind with various proteins and hence are used in targeted drug delivery and gene therapy.
Features and Benefits
The PEG coating decreases the cytotoxicity and increases efficiency of GNPs in targeted drug delivery. PEG increases the stability of the nanoparticles and prevents agglomeration. 
