Dissecting Colloidal Stabilization Factors in Crowded
Polymer Solutions by Forming Self-Assembled Monolayers on Gold Nanoparticles
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Abstract
An
ideal colloidal system should be highly stable in a diverse
range of buffer conditions while still retaining its surface accessibility.
We recently reported that dispersing citrate-capped gold nanoparticles
(AuNPs) in polymers, such as polyethylene glycol (PEG), can achieve
such a goal because of contributions from depletion stabilization.
Because AuNPs can weakly adsorb PEG to exert steric stabilization
and the remaining citrate can impart charge stabilization, the extent
of the contribution of depletion stabilization is unclear. In this
work, we aim to dissect the contribution of each stabilizing factor.
This is achieved by coating AuNPs with a layer of thiolated compound,
which inhibits the adsorption of PEG and also allows for the control
of surface charge. We found that depletion stabilization alone was
insufficient to stabilize AuNPs at room temperature. However, when
working together with other stabilization mechanisms, ultrahigh stability
can be achieved. The size of both AuNPs and PEG was systematically
varied, and the trends were compared to theoretical calculations.
Finally, we report the importance of the surface chemistry of commercial
AuNPs