Probing the Protein Corona of Nanoparticles in a Fluid Flow by Single-Particle Differenced Resonance Light Scattering Correlation Spectroscopy.

The protein corona of nanoparticles (NPs) plays a crucial role in determining NPs' biological fates. Here, a novel measurement strategy was proposed to in situ investigate the protein corona formed in the NPs with the home-built dual-wavelength laser-irradiated differenced resonance light scattering correlation spectroscopy (D-RLSCS) technique, combined with the modified generation method of the D-RLSCS curve. With the measurement strategy, the dissociation constants and the binding rates between proteins and gold nanoparticles (GNPs) were determined based on the binding-induced ratiometric diffusion change of NPs (the ratio of characteristic rotational diffusion time to translational one), using the formation of the protein corona of bovine serum albumin (BSA) or fibrinogen (FIB) on gold nanoparticles as a model. It was found that BSA shows a stronger binding constant and faster binding rate to gold nanospheres (GNSs) compared with those of FIB. Meanwhile, the dynamic behavior of the protein corona in a fluid flow mimicking biological vessels was further studied based on the combination of the D-RLSCS technique with a microfluidic channel. The measurement results indicated that some "loose" protein corona layers would strip off the surface of NPs within the microchannel due to the fluid sheath force. This method can provide the comprehensive information of a protein corona by averaging the diffusion behavior of many particles different from some conventional methods and overcome the shortcomings of conventional correlation spectroscopy methods.