The utility of nanoparticles for myriad biomedical applications is contingent upon their ability to reach the target site in vivo. Interactions of these nanoparticles with proteins influences both basic physicochemical properties (size, charge, extent of aggregation) and efficacy of targeting. Here, we report the investigation of the interaction of polymer-coated gold nanoparticles (AuNPs) with either a single protein (human serum albumin, HSA) or a model complex biological fluid containing many proteins (human serum, HS). We assessed the utility of a polymer coating, which consists of either poly(ethylene glycol) (PEG) or a zwitterionic polypeptide of predominantly glutamate and lysine (PEK), upon exposure of AuNPs to HSA or HS. Dynamic light scattering and zeta potential measurements indicate substantive changes in nanoparticle aggregation and surface charge following interaction for bare and both types of polymer-coated nanoparticles. The size (~150 nm) and surface charge (~ −15 mV)  is independent of the initial AuNP state. Parallel work indicates that these changes influence the stability of the particles. Two spectroscopic techniques enabled determination that the total amount of protein adhering in the inner or “hard” corona is significant and not reduced by the presence of polymer coatings on the AuNPs. Using HPLC-MS, we identified the proteins within HS that adhered to each AuNPs type. Particularly at high HS concentration, the proteins sticking to all particle types, regardless of the surface modification, was significantly larger in number than the unique proteins adhering to any specific AuNP type.

Protein interactions with stealth-coated gold nanoparticles

255th National Meeting (2018)

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