Thiol-terminated polyethylene glycol (PEG) iscommonly used to functionalize the surface of gold nanoparticles(AuNPs) in order to improve their in vivo stabilityand to avoid uptake by the reticular endothelial system.Although it has been reported that AuNPs functionalized withtethered PEG are stable in biological media, the influence ofchain density remains unclear. This study investigates theinfluence of PEG capping density on the stability of washedand dried AuNPs in: water, phosphate-buffered saline solution(PBS), phosphate-buffered saline solution containing bovineserum albumin (PBS/BSA), and dichloromethane (DCM).PEG coating had a dramatic effect on stability enabling stablesuspensions to be produced in all the media studied. A linearrelationship was observed between capping density andstability in water and DCM with a somewhat lower stabilityobserved in PBS and PBS/BSA. A maximum PEG loadinglevel of ∼14 wt.% was achieved, equivalent to a PEG surfacedensity of ∼1.13 chains/nm2.
Dixon, D., Meenan, BJ., Manson, J., & Kumar, D. (2011). Polyethylene glycol functionalized gold nanoparticles:the influence of capping density on stability in various media. Gold Bulletin, 44(2), 99-105. https://doi.org/10.1007/s13404-011-0015-8