Fabrication of hexagonal boron nitride based 2D nanopore sensor for the assessment of electro-chemical responsiveness of human serum transferrin protein

In this work, we present a step-by-step workflow for the fabrication of 2D hexagonal boron nitride (h-BN) nanopores which are then used to sense holo-human serum transferrin (hSTf) protein at pH similar to 8 under applied voltages ranging from +100 mV to +800 mV. 2D nanopores are often used for DNA, however, there is a great void in the literature for single-molecule protein sensing and this, to the best of our knowledge, is the first time where h-BN-a material with large band-gap, low dielectric constant, reduced parasitic capacitance and minimal charge transfer induced noise-is used for protein profiling. The corresponding Delta G (change in pore conductance due to analyte translocation) profiles showed a bimodal Gaussian distribution where the lower and higher Delta G distributions were attributed to (pseudo-) folded and unfolded conformations respectively. With increasing voltage, the voltage induced unfolding increased (evident by decrease in Delta G) and plateaued after similar to 400 mV of applied voltage. From the Delta G versus voltage profile corresponding to the pseudo-folded state, we calculated the molecular radius of hSTf, and was found to be similar to 3.1 nm which is in close concordance with the literature reported value of similar to 3.25 nm.