Upon introduction into biological environments, nanoparticles (NPs) are quickly covered by a dense layer of proteins – the protein corona. The process of protein corona formation greatly depends on the interactions of proteins with the surface of highly curved NP surfaces and competition between proteins for NP binding sites. The protein corona determines the NPs surface charge, size, and aggregation behavior, greatly defining the NPs identity in the body. So, to control the biological response of coated and/or functionalized NPs we must understand, at the molecular level, the surface structure and orientation of the proteins involved in the protein corona and its formation. We demonstrate that interface specific ultrafast sum frequency scattering (SFS) spectroscopy is ideal to directly determine <i>in situ </i>the structure, orientation, and mode of action by which proteins interact at NP interfaces.<br/><br/>Initially, we utilized SFS spectroscopy on a model system of hexadecane oil NPs and leucine-lysine (LK) peptides that are known to adopt a single secondary structure, either a α-helix or β-strand, at hydrophobic interfaces. The collected amide I SFS spectrum is indicative of ordered peptides at the interface of the NPs. Building upon the model system as our starting point, we studied a series of NP sizes, thus changing the curvature, to investigate its impact on protein structure and orientation. Expanding from the ideal model system, we have observed a larger protein with several secondary structures within its tertiary structure, protein G B1 domain (GB1), interacting at a lipid NP interface. Here, we monitored the surface of the particle by the ester bond of the lipid as well as the Amide I SFS spectrum of the GB1 protein. Altogether, with SFS we have made initial strides to further the understanding of protein corona formation at particle interfaces.

Protein structure at nanoparticle interfaces

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.