Kavli Affiliate: Rudolf Podgornik
| First 5 Authors: Vijay Yadav, Vijay Yadav, , ,
| Summary:
The ability to precisely control surface charge using charged polymers is
fundamental to many nanotechnology applications, enabling the design and
fabrication of materials with tailored properties and functionalities. Here, we
study the effect of charge regulation (CR) on the interaction between two
nanoparticles (NPs) mediated by an oppositely charged polyelectrolyte (PE) in
an electrolyte solution. To this end, we employ a hybrid CR Monte Carlo
(CR-MC)/molecular dynamics (MD) simulation framework to systematically explore
the effects of pH, salt concentration, and polymer chain length on NP surface
charge behavior. For comparison, we also conduct MD simulations under constant
charge (CC) conditions. Our results reveal that CR enhances PE adsorption onto
NP surfaces compared to the CC case, where polymer bridging dominates across a
wide range of NP intersurface separations. This enhanced adsorption under CR
leads to a weak net repulsion driven by osmotic forces. In contrast, the CC
model yields a stronger net attraction due to the bridging force. Furthermore,
we find that the CR effects are more pronounced at a low salt concentration,
whereas at a high salt concentration, counterion screening dominates in both CR
and CC cases, resulting in similar interaction profiles. These findings
highlight the importance of incorporating charge regulation in characterizing
NP interactions within a complex biochemical environment, particularly in the
presence of low salt concentrations.
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