Search for: All records

We present a successful discrimination of heparin, FGF-1, and heparin–FGF-1 complexes at a single-molecule level through solid-state nanopores. 

Transferrin, a central player in iron transport, has been recognized not only for its role in binding iron but also for its interaction with other metals, including titanium. This study employs solid-state nanopores to investigate the binding of titanium ions [Ti(IV)] to transferrin in a single-molecule and label-free manner. We demonstrate the novel application of solid-state nanopores for single-molecule discrimination between apo-transferrin (metal-free) and Ti(IV)-transferrin. Despite their similar sizes, Ti(IV)-transferrin exhibits a reduced current drop, attributed to differences in translocation times and filter characteristics. Single-molecule analysis reveals Ti(IV)-transferrin’s enhanced stability and faster translocations due to its distinct conformational flexibility compared to apo-transferrin. Furthermore, our study showcases solid-state nanopores as real-time monitors of biochemical reactions, tracking the gradual conversion of apo-transferrin to Ti(IV)-transferrin upon the addition of titanium citrate. This work offers insights into Ti(IV) binding to transferrin, promising applications for single-molecule analysis and expanding our comprehension of metal–protein interactions at the molecular level. 

ABSTRACT Detection of ultra‐short peptides is one of the critical steps toward deeper understanding of proteins and the sequencing of amino acids using solid‐state nanopores. The ability of solid‐state nanopores to detect these ultra‐short peptides can help us reveal their hydrodynamic state under different conditions like the concentrations and the external voltage, which may further guide the future development in this field for deeper investigation and possible improvement. In this study, we fabricate Si_xN_ynanopores by CDB with various pore sizes and use them to detect ultra‐short peptides comprised of five different amino acids. The peptide translocation events are extracted under various external voltages. Optimal experimental conditions such as the concentration of electrolytes and analytes, and the range of external voltage are investigated and compared. The statistical results based on volume exclusion analysis indicate that a significant portion of peptides exist in aggregation form. Due to the limitations of Si_xN_ynanopores such as the thickness and the noise, most of the single peptide signals are masked under the baseline noise. In addition, the results show that peptide–pore interactions are dependent upon the diameter of the nanopore. Higher voltage may also influence the degree of peptide aggregations. This study serves to further comprehend the physical and chemical properties of peptides, find possible ways to improve the performance of solid‐state nanopores in the area of protein and peptide detections, and indicate the potential improvements in solid‐state nanopore‐based peptide sequencing.