Role of bovine serum albumin and humic acid in the interaction between SiO₂ nanoparticles and model cell membranes

Silica nanoparticles (SiO₂ NPs) can cause health hazard after their release into the environment. Adsorption of natural organic matter and biomolecules on SiO₂ NPs alters their surface properties and cytotoxicity. In this study, SiO₂ NPs were treated by bovine serum albumin (BSA) and humic acid (HA) to study their effects on the integrity and fluidity of model cell membranes. Giant and small unilamellar vesicles (GUVs and SUVs) were prepared as model cell membranes in order to avoid the interference of cellular activities. The microscopic observation revealed that the BSA/HA treated (BSA-/HA-) SiO₂ NPs took more time to disrupt membrane than untreated-SiO₂ NPs, because BSA/HA adsorption covered the surface Si−OH/Si−O^- groups and weakened the interaction between NPs and phospholipids. The deposition of SiO₂ NPs on membrane was monitored by a quartz crystal microbalance with dissipation (QCM-D). Untreated- and HA-SiO₂ NPs quickly disrupted the SUV layer on QCM-D sensor; BSA-SiO₂ NPs attached on the membranes but only caused slow vesicle disruption. Untreated-, BSA- and HA-SiO₂ NPs all caused the gelation of the positively-charged membrane, which was evaluated by the generalized polarity values. HA-SiO₂ NPs caused most serious gelation, and BSA-SiO₂ NPs caused the least. Our results demonstrate that the protein adsorption on SiO₂ NPs decreases the NP-induced membrane damage. - Highlights: • BSA adsorption on SiO2 NPs mitigates the NP-induced membrane disruption. • BSA-treated SiO2 NPs cause least membrane gelation. • HA-treated SiO2 NPs cause most serious membrane gelation. - Bovine serum albumin adsorption on silica nanoparticles mitigates the particle-induced membrane disruption and phase gelation.