Impedimetric and single-frequency capacitance spectroscopy strategy in label-free rapid screening of lactoferrin

Abstract

The complex structure of lactoferrin as a large bio-macromolecule with about 700 amino acids makes it a difficult target for electrochemical determination. Here, inspired by the inhibitory function of (S)-1-(3-Mercapto-2-methyl-1-oxopropyl)-L-proline (MOP) for deactivation of angiotensin-converting enzyme, a new approach for the determination of lactoferrin was developed by exploiting a mixed monolayer of MOP/3-sulfanylpropan-1-ol (MOP-SP) as a novel lactoferrin biosensing platform (LBP). Electrochemical techniques, FE-SEM, AFM, UV-Vis, Raman spectroscopy, and electrochemical quartz crystal microbalance (EQCM) were used for tracking the LBP fabrication process and evaluating the efficiency of the LBP responses for the LF determination. Analytical performance of the fabricated LBP toward the selective and sensitive LF detection was investigated using the electrochemical impedance spectroscopy (EIS) technique. Using EIS, the linear range and detection limit for LF determination were obtained as 125 nM to 3.250 μM and 65.2 nM, respectively. Also, capacitive analysis as a new, efficient and sensitive technique in protein detection was performed for reducing the detection time with the linear range and detection limit of 500 nM to 3.250 μM and 375 nM, respectively. Finally, the fabricated LBP was successfully applied for LF determination in the colostrum samples.