The optimization of electrochemical immunosensors to detect epithelial sodium channel as a biomarker of hypertension

Abstract

The epithelial sodium channel (ENaC) is a transmembrane protein that regulates the balance of sodium salt levels in the body through its expression in various tissues. The increase in sodium salt in the body is related to the expression of ENaC, thereby increasing blood pressure. Therefore, overexpression of the ENaC protein can be used as a biomarker for hypertension. The detection of ENaC protein using anti-ENaC in the biosensor system has been optimized with the Box-Behnken experimental design. The steps carried out in this research are screen-printed carbon electrode modification with gold nanoparticles, then anti-ENaC was immobilized using cysteamine and glutaraldehyde. Optimum conditions of the experiment, such as anti-ENaC concentration, glutaraldehyde incubation time, and anti-ENaC incubation time, were optimized using the Box-Behnken experimental design to determine the factors that influence the increase in immunosensor current response and the optimum conditions obtained were then applied to variations in ENaC protein concentrations. The optimum experimental conditions for anti-ENaC concentration were 2.5 µg/mL, the glutaraldehyde incubation time was 30 minutes, and the anti-ENaC incubation time was 90 minutes. The developed electrochemical immunosensor has a detection limit of 0.0372 ng/mL and a quantification limit of 0.124 ng/mL for the ENaC protein concentration range of 0.09375 to 1.0 ng/mL. Thus, the immunosensor generated from this study can be used to measure the concentration of normal urine samples and those of patients with hypertension.

Hydroxyapatite-Gold Modified Screen-Printed Carbon Electrode for Selective SARS-CoV-2 Antibody Immunosensor

“…The result shows the enhanced electron transfer due to the composite’s high conductivity and the increase in the overall electroactive area, consequently increasing the current response, as evidenced by the improved current of SPCE/AuNP from 5.395 to 21.340 μA (Figure S2). The high conductivity of AuNP increases the electroactive properties of the electrode and provides many active regions for protein binding and electron transfer …”

“…The high conductivity of AuNP increases the electroactive properties of the electrode and provides many active regions for protein binding and electron transfer. 31 Figure 4b presents the Nyquist plot of bare SPCE and SPCE/HA-Au, showing that R CT decreases after the SPCE is modified by HA-Au from 2.377 to 1.680 Ω, corresponding to the smaller electron transfer resistance on the surface of the electrode in SPCE/HA-Au compared to the bare SPCE. The current measurements exhibit an inverse relationship with those observed at SPCE/HA-Au, as per Ohm's Law, which states that resistance is inversely proportional to current.…”