Adsorption of bovine serum albumin on silicon dioxide nanoparticles: Impact of pH on nanoparticle–protein interactions

Abstract

Bovine serum albumin (BSA) adsorbed on amorphous silicon dioxide (SiO2) nanoparticles was studied as a function of pH across the range of 2 to 8. Aggregation, surface charge, surface coverage, and protein structure were investigated over this entire pH range. SiO2 nanoparticle aggregation is found to depend upon pH and differs in the presence of adsorbed BSA. For SiO2 nanoparticles truncated with hydroxyl groups, the largest aggregates were observed at pH 3, close to the isoelectric point of SiO2 nanoparticles, whereas for SiO2 nanoparticles with adsorbed BSA, the aggregate size was the greatest at pH 3.7, close to the isoelectric point of the BSA-SiO2 complex. Surface coverage of BSA was also the greatest at the isoelectric point of the BSA-SiO2 complex with a value of ca. 3 ± 1 × 1011 molecules cm−2. Furthermore, the secondary protein structure was modified when compared to the solution phase at all pH values, but the most significant differences were seen at pH 7.4 and below. It is concluded that protein–nanoparticle interactions vary with solution pH, which may have implications for nanoparticles in different biological fluids (e.g., blood, stomach, and lungs).

Analyzing the Interaction between Two Different Types of Nanoparticles and Serum Albumin

“…The analysis of BSA adsorption on amorphous SiO 2 NPs revealed that coverage with this protein was the greatest at the isoelectric point of the BSA-SiO 2 complex with a value of ca. 3 ± 1 × 10 11 molecules cm −2 [41]. A previous study regarding the interaction of BSA with TiO 2 (~22 nm) and SiO 2 (~14 nm) NPs noticed a higher coverage on TiO 2 NPs, the BSA being completely unfold on TiO 2 NPs and having an extended conformation on SiO 2 NPs [42].…”

Adsorption of Extracellular Polymeric Substances Derived from S. cerevisiae to Ceria Nanoparticles and the Effects on Their Colloidal Stability

“…Indeed, Safinajafabadi and others also reported that the colloidal stability was enhanced by the adsorption of saccharides including glucose, maltose, and dextrin [46]. Protein (bovine serum albumin) adsorption can also enhance the dispersibility of SiO2 nanoparticles near the isoelectric point [47]. In general, the adsorption of organic matter forms a steric barrier over the particles, leading to the colloidal stabilization.…”

Reversible pH Responsive Bovine Serum Albumin Hydrogel Sponge Nanolayer

“…Multiple articles have extensively reported on the BSA molecules sorption phenomenon at different interfaces such as gold (Dennison et al, 2017), mica (Fitzpatrick et al, 1992), silicon (Jachimska et al, 2016;Givens et al, 2017), and cellulose (Mohan et al, 2014;Lombardo et al, 2017). The adsorbed BSA molecule's conformation and the topology of the formed layer are strongly affected by pH, ionic strength and temperature.…”