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

Saharia, Jugal, Bandara, Y. M. Nuwan D. Y., Lee, Jung Soo, Wang, Qingxiao, Kim, Moon J., Kim, Min Jun
Electrophoresis 2020 v.41 no.7-8 pp. 630-637
DNA, blood serum, boron nitride, capacitance, dielectric properties, electric potential difference, electrophoresis, humans, nanopores, normal distribution, pH, protein composition, transferrin
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 ∼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 ΔG (change in pore conductance due to analyte translocation) profiles showed a bimodal Gaussian distribution where the lower and higher ΔG distributions were attributed to (pseudo‐) folded and unfolded conformations respectively. With increasing voltage, the voltage induced unfolding increased (evident by decrease in ΔG) and plateaued after ∼400 mV of applied voltage. From the ΔG versus voltage profile corresponding to the pseudo‐folded state, we calculated the molecular radius of hSTf, and was found to be ∼3.1 nm which is in close concordance with the literature reported value of ∼3.25 nm.