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).
|State||Published - Jun 1 2017|
Bibliographical noteFunding Information:
Transmission electron microscopy was completed using the Central Microscopy Facility at the University of Iowa. Thermogravimetric analysis was done using the instrumentation in C. Allan Guymon laboratory at the University of Iowa in the Department of Chemical and Biochemical Engineering; assistance and training were provided by Jacob McLaughlin. This work was supported by the NSF CBET Award (NSF-1424502 and 1640936). Nina D. Diklich was supported by NSF REU Grant No. 1359063. Additional support for Brittany E. Givens was provided by the Alfred P. Sloan Foundation through the University of Iowa Center for Exemplary Mentoring. The authors also acknowledge helpful discussions with Zhenzhu Xu, Sarah C. Larsen, Imali A. Mudunkotuwa, and Sean E. Lehman.
ASJC Scopus subject areas
- Chemistry (all)
- Materials Science (all)
- Biochemistry, Genetics and Molecular Biology (all)
- Physics and Astronomy (all)