Using Molecular Probe Adsorption to Characterize the Nanoparticle Corona Phase and Molecular Recognition.

The nanoparticle corona─a molecular layer adsorbed on nanoparticle surfaces─is critical for controlling molecular interactions and enabling applications in catalysis, nanoparticle separations, and sensing technologies. However, to date, characterizing the adsorbed surface area occupied by the corona phase has been difficult and not accessible with conventional particle sizing methods. Herein, we advance the technique of molecular probe adsorption (MPA) to measure this surface area by applying it to a large number of data sets. MPA employs a fluorescent probe that is quenched on adsorption to the nanoparticle surface to quantify the solvent-exposed surface area. We use MPA to evaluate 20 new carbon nanotube (CNT) corona phases and further analyze five previously studied constructs that have been used as nanosensors. We find that polymer stiffness, measured by its persistence length, correlates with corona phase CNT surface coverage, providing a new design criterion. We also establish a structure-property relationship linking MPA-derived surface area to probe adsorption parameters, noting that single-stranded DNA and high-molecular-weight polymers exhibit differing probe-corona interactions, with binding affinities varying by a factor of nearly 2.7. MPA-derived surface areas are shown to complement molecular-dynamics/thermodynamic calculations to predict binding affinities for 42 phytohormones entirely in silico, providing a means to screen corona phases virtually. In this way, MPA is shown to be a predictive design tool for nanoparticle and nanosensor applications.