Developing a mechanistic understanding of protein dynamics and conformational changes at polymer interfaces is critical for a range of processes including industrial protein separations. Salting out is one example of a procedure that is ubiquitous in protein separations yet is optimized empirically because there is no mechanistic description of the underlying interactions that would allow predictive modeling. Here, we investigate peak narrowing in a model transferrin–nylon system under salting out conditions using a combination of single-molecule tracking and ensemble separations. Distinct surface transport modes and protein conformational changes at the negatively charged nylon interface are quantified as a function of salt concentration. Single-molecule kinetics relate macroscale improvements in chromatographic peak broadening with microscale distributions of surface interaction mechanisms such as continuous-time random walks and simple adsorption–desorption. Monte Carlo simulations underpinned by the stochastic theory of chromatography are performed using kinetic data extracted from single-molecule observations. Simulations agree with experiment, revealing a decrease in peak broadening as the salt concentration increases. The results suggest that chemical modifications to membranes that decrease the probability of surface random walks could reduce peak broadening in full-scale protein separations. More broadly, this work represents a proof of concept for combining single-molecule experiments and a mechanistic theory to improve costly and time-consuming empirical methods of optimization.

Serum albumin can template gold nanorods into chiral assemblies, but the aggregation mechanism is not entirely understood. We used circular dichroism spectroscopy and scanning electron microscopy to investigate the role of protein identity/ shape, protein/nanorod ratio, and surfactants on chiral protein− nanorod aggregation. Three globular proteinsserum albumin, immunoglobulin, and transferrinproduced similarly sized chiral protein−nanorod aggregates. In solution these aggregates exhibited circular dichroism at the plasmon resonance that switched direction at specific protein/nanorod concentration ratios. Our explanation is that the extent of protein crowding influences protein conformation and therefore protein−protein interactions, which in turn direct nanorod aggregation into preferentially left-or right-handed structures. The fibrous proteins fibrinogen and fibrillar serum albumin also produced chiral nanorod aggregates but did not exhibit a ratio-dependent switch in the circular dichroism direction. In addition, cetyltrimethylammonium bromide micelles prevented all aggregation, providing compelling evidence that protein−protein interactions are crucial for chiral protein−nanorod aggregate formation. The protein-dependent variations in circular dichroism and aggregation reported here present opportunities for future chiral nanostructure engineering and biosensing applications.

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Solvated electrons are powerful reducing agents capable of driving some of the most energetically expensive reduction reactions. Their generation under mild and sustainable conditions remains challenging though. Using near-ultraviolet irradiation under low-intensity one-photon conditions coupled with electrochemical and optical detection, we show that the yield of solvated electrons in water is increased more than 10 times for nanoparticle-decorated electrodes compared to smooth silver electrodes. Based on the simulations of electric fields and hot carrier distributions, we determine that hot electrons generated by plasmons are injected into water to form solvated electrons. Both yield enhancement and hot carrier production spectrally follow the plasmonic near-field. The ability to enhance solvated electron yields in a controlled manner by tailoring nanoparticle plasmons opens up a promising strategy for exploiting solvated electrons in chemical reactions.