(16d) Reorientation of Cytochrome c on Silica Nanoparticles Induced By pH

Authors: 
Wu, Y., Louisiana State University
Meissner, J., Technische Universität Berlin
Shelton, W. A. Jr., Louisiana State University
Findenegg, G. H., Technical University Berlin
Bharti, B., Louisiana State University
An ability to control the orientation of proteins on nanoparticles has a direct impact on the properties of functional materials including purification of antibodies and modulating enzymatic activity. Thus, designing next generation of biocompatible nanomaterials requires a better understanding of the interfacial bio-nano interactions. We investigate the interaction between a model protein, cytochrome c, and silica nanoparticles over a wide range of pH by combining small-angle neutron scattering, adsorption measurements, and molecular dynamics simulations. We show that at pH < 4 the protein adsorbs with a head-on configuration, but with increasing pH, a reorientation of the protein to a side-on orientation takes place. Here, we will discuss the role of interfacial electrostatic interactions on governing the local orientation of cytochrome c on silica nanoparticles.