Regulation of Protein Transport in Functionalized PET Nanopores.

Facilitated translocation is a critical mechanism for transporting substances in biological systems, where molecular and ionic species move across the biological membrane with the help of specific transmembrane protein ion channels. In this work, we systematically examined protein transport in three poly(ethylene terephthalate) (PET) nanopores modified with different types of surface functions (hydroxyl, phenyl, and amine). We found that the event signature as well as the kinetics and thermodynamics of protein movement in the PET nanopore varied significantly with the change in the surface function in the pore. In addition to the electrophoretic effect, other factors such as diffusion, electro-osmotic effect, ion selectivity of the channel, and affinity strength between the protein species and the surface functional group of the nanopore also play significant roles in the protein transport. Although properly functionalized individual PET nanopores can be used as stochastic elements for rapid protein differentiation and characterization, enhanced resolution and accuracy could be accomplished by employing an array of PET nanopores having different inner surface functional groups to characterize proteins based on their collective responses. Given the important roles proteins play in living organisms and their applications as biomarkers in early disease diagnosis and prognosis, the pattern-recognition solid-state nanopore-sensing strategy for protein detection and characterization developed in this work may find useful applications in various fields.