Graphene Nanochannels for Label-Free Protein Detection and Protein-Protein Interaction Analysis

Resistive pulse sensing, utilizing the electrophoretic movement of proteins through nanopores or nanochannels, has emerged as a promising method for label-free protein detection and characterization. However, traditional solid-state materials, such as Si, SiO₂, SiN_x, and polydimethylsiloxane, suffer from significant limitations, including nonspecific protein interactions with solid surfaces that cause channel blockage, preventing the long-term reliability of resistive pulse sensing. In contrast, two-dimensional materials have attracted much attention due to their potential in biomolecular detection because of their ultrathin thickness, ultrahigh surface flatness, and extremely high mechanical strength. Among them, the extremely high surface flatness helps to reduce the transport resistance of biomolecules moving on its surface. Here, we demonstrate that graphene nanochannels, fabricated via layer assembly, provide exceptional properties for protein analysis, including low noise, high surface smoothness, and minimal nonspecific protein adsorption. These attributes make graphene nanochannels an ideal platform for long-term, stable protein characterization. Our findings show that these nanochannels can effectively differentiate between five distinct proteins based on resistive pulse signals. Additionally, we utilized the nanochannels to monitor the binding dynamics of immunoglobulin G (IgG) and the aggregation process of β-lactoglobulin, revealing the capability of graphene nanochannels in detecting protein-protein interactions and molecular conformational changes. This work highlights the potential of graphene nanochannels as powerful tools for label-free, highly sensitive protein identification and interaction studies, marking a significant advancement in biosensing technology in biomolecular research and diagnosis.