The properties of nanoparticles (NPs) in biological fluids differ from their behavior in water due to the association of different proteins to the NP surface, forming a "protein corona" around the NPs. These proteins bind strongly to the NPs and affect the NPs' interactions with their environment. The goal of this proposal is to quantify the dynamics of proteins binding to NPs and to determine how the proteins may change their structure upon binding. The project will investigate model proteins, as well as proteins in blood plasma. The inclusion of experiments with whole plasma is an attractive feature of this proposed work, as whole plasma reflects the complexity of real-world conditions. The results of this research will be important for the understanding of the fate of nanoparticles, particularly, the bio-accumulation of nanoparticles in the food chain. In addition, understanding the dynamics of protein coating of NPs can be useful for the development of approaches that intentionally coat NPs with proteins in order to prevent other proteins from binding as a strategy to ensure that the NPs do not cause adverse effects on the environment. The PI and Co-PI are both active in outreach to the K-12 community and mentoring of undergraduate and graduate students.
While it is believed that the corona changes over time, as initially the most abundant proteins bind, but are then replaced with proteins that have the largest affinity, very little is known about the time scales of this dynamic exchange among different proteins. The goal of this proposal is to quantify the time-scales of protein-binding to NPs and to determine binding-induced structural changes of the proteins. Correlation spectroscopy will be used to determine the equilibrium protein-NP binding constant and number of bound proteins. The approach will be extended to measure competitive binding among different proteins to the same or possibly different nanoparticles. For protein folding/unfolding on NPs, the PIs will use CD spectroscopy on individual nanoparticles (with the goal of achieving single protein detection levels) and smFRET (single molecule fluorescence resonance energy transfer) microscopy of donor-acceptor labeled proteins. The investigators have unique and complementary strong expertise in the proposed area of research.
