Amyloid-Like Assembly to Form Film at Interfaces: Structural Transformation and Application

Protein-based biomaterials are attracting broad interest for their remarkable structural and functional properties. Disturbing the native protein's three-dimensional structural stability in vitro and controlling subsequent aggregation is an effective strategy to design and construct protein-based biomaterials. One of the recent developments in regulating protein structural transformation to ordered aggregation is amyloid assembly, which generates fibril-based 1D to 3D nanostructures as functional materials. Especially, the amyloid-like assembly to form films at interfaces has been reported, which is induced by the effective reduction of the intramolecular disulfide bond. The main contribution of this amyloid-like assembly is the large-scale formation of protein films at interfaces and excellent adhesion to target substrates. This review presents the research progress of the amyloid-like assembly to form films and related applications and thereby provides a guide to exploiting protein-based biomaterials.     

Use of a solid-state nanopore for profiling the transferrin receptor protein and distinguishing between transferrin receptor and its ligand protein

A nanopore device is capable of providing single-molecule level information of an analyte as they translocate through the sensing aperture—a nanometer-sized through-hole—under the influence of an applied electric field. In this study, a silicon nitride (Si_xN_y)-based nanopore was used to characterize the human serum transferrin receptor protein (TfR) under various applied voltages. The presence of dimeric forms of TfR was found to decrease exponentially as the applied electric field increased. Further analysis of monomeric TfR also revealed that its unfolding behaviors were positively dependent on the applied voltage. Furthermore, a comparison between the data of monomeric TfR and its ligand protein, human serum transferrin (hSTf), showed that these two protein populations, despite their nearly identical molecular weights, could be distinguished from each other by means of a solid-state nanopore (SSN). Lastly, the excluded volumes of TfR were experimentally determined at each voltage and were found to be within error of their theoretical values. The results herein demonstrate the successful application of an SSN for accurately classifying monomeric and dimeric molecules while the two populations coexist in a heterogeneous mixture.