BSA adsorption on gold nanoparticles investigated under static and flow conditions

In this work time- and frequency-resolved spectroscopic techniques are employed for the investigation of protein adsorption (protein corona formation) on gold nanoparticles. We will follow the interaction of ~ 20 nm citrate-capped gold nanoparticles with the model protein bovine serum albumin under both static and flow conditions, to monitor in details the binding process in the early stages. In parallel to standard techniques (UV-Visible absorption, circular dichroism and fluorescence spectroscopy), an advanced technique such as fluorescence correlation spectroscopy is employed for the characterization of the kinetic and thermodynamic constants involved in protein corona formation. The dissociation constant characterizing adsorption of bovine serum albumin on gold nanoparticles is measured in solutions under static conditions as a function of protein concentration. A preliminary characterization of the adsorption dynamic, instead, is achieved by fabrication of a simple Y shaped microfluidic device in polydimethylsiloxane and glass. Water solutions of nanoparticles and protein are injected in the two inlets and mixing of the two species occurs only in the central part of the main channel. Following the evolution of the fluorescence correlation spectroscopy signal along the main channel of the microfluidic device provides adsorption kinetic data with a time resolution defined only by the flow rate applied at the inlets.