A Sensitive capacitive immunosensor for direct detection of human heart fatty acid-binding protein (h-FABP)

Electrochemical Detection of Plasma Immunoglobulin as a Biomarker for Alzheimer’s Disease

“…Additionally, when dealing with electrochemical immunosensors, it is generally anticipated that the formation of an immunocomplex on the antibody-coated surface upon exposure to antigen, a further decrease in current should be observed. These characteristics have been observed for immunosensors in the majority of studies [ 27 , 28 , 29 , 30 ]. The EIS results further verify this observation as the Nyquist plot in Figure 4 shows that the charge transfer resistance increases with the exposure to increasing plasma concentrations.…”

“…These initial layers, used to modify the electrode surface, appear to have blocking properties. This is due to the insulating properties of the protein layer [ 27 , 28 , 29 , 30 ]. As the surface is exposed to increasing concentrations of plasma, the accessibility of the Au surface to the redox probe becomes increasingly limited, leading to lower peak currents.…”

“…This phenomenon can be explained by taking the capacitance of the system into consideration. As reported previously [ 30 ], the total system capacitance for an Au/SAM/Antibody sensor involved three capacitive components in series is given by Equation (1) below: where C T is the total system capacitance, C SAM is the capacitance of the SAM layer, C ab is the capacitance of the biolayer and C dl is the double layer capacitance. The capacitance Equation (2) for a metal surface in contact with an electrolyte is: where, for a bare electrode surface, C is the capacitance of the double layer ( C dl ), ε is the dielectric constant of the electrolyte (80 for water and much lower for organic materials such as proteins) and ε 0 is the permittivity of the vacuum given to be 8.023 × 10 −12 .…”

Electrochemical immunosensor development based on core-shell high-crystalline graphitic carbon nitride@carbon dots and Cd0.5Zn0.5S/d-Ti3C2Tx MXene composite for heart-type fatty acid–binding protein detection

“…EIS technique was carried out in order to evaluate the validity of the electrochemical immunosensor [21]. Table S2 demonstrates the results obtained by the two different techniques for h-FABP detection.…”

“…In addition, impedimetric immunosensor was prepared based on gold electrode modified with 11-mercaptoundecanoic acid, suggesting linearity of 98.0 pg mL −1 -100.0 ng mL −1 with a LOD of 117.0 pg mL −1 for h-FABP recognition [20]. Capacitive immunosensor based on gold electrode modified with 11-mercaptoundecanoic acid was also constructed and showed a LOD of 0.84 ng mL −1 for h-FABP recognition [21]. Finally, electrochemiluminescence immunosensor for h-FABP recognition based on 2D-nickel metal-organic framework nanosheets was developed and a LOD of 44.5 fg mL −1 was obtained [22].…”