The influence of solution chemistry and soft protein coronas
on the interactions between citrate-coated silver nanoparticles (AgNPs) and
model biological membranes was investigated by assembling supported lipid
bilayers (SLBs) composed of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine
(DOPC) on silica crystal sensors in a quartz crystal microbalance with
dissipation monitoring (QCM-D). Our results show that the deposition rates
of AgNPs on unmodified silica surfaces increased with increasing electrolyte
concentrations under neutral pH conditions. Similar trends were observed
when AgNPs were deposited on SLBs, hence indicating that the deposition of
AgNPs on model cell membranes was controlled by electrostatic interactions.
In the presence of human serum albumin (HSA) proteins at both pH 7 and
pH 2, the colloidal stability of AgNPs was considerably enhanced due to the formation of HSA soft coronas surrounding the
nanoparticles. At pH 7, the deposition of AgNPs on SLBs was suppressed in the presence of HSA due to steric repulsion between
HSA-modified AgNPs and SLBs. In contrast, pronounced deposition of HSA-modified AgNPs on SLBs was observed at pH 2.
This observation was attributed to the reduction of electrostatic repulsion as well as conformation changes of adsorbed HSA
under low pH conditions, resulting in the decrease of steric repulsion between AgNPs and SLBs.
Environ. Sci. Technol. 2016, 50, 2301−2309