A voltammetric immunosensor based on gold nanoparticle - Anti-ENaC bioconjugate for the detection of epithelial sodium channel (ENaC) protein as a biomarker of hypertension

Abstract

Epithelial sodium channel (ENaC) is a protein that has a central role in the development of hypertension. ENaC is a transmembrane protein that overexpressed in arterial hypertension patients. The expression of ENaC is proportional to sodium intake and clinically related to hypertension. The concentration of ENaC excreted in the urine of patients can be used as a biomarker of hypertension. Herein, we report a gold nanoparticle-bioconjugate based electrochemical immunosensor for the detection of ENaC. The bioconjugate (AuNP/HS-PEG-COOH/Anti-ENaC) was immobilized on the surface of a gold-screen printed carbon electrode treated with cysteamine (SPCE/Au-cys) via covalent bonds between the -NH2 group of the cysteamines and –COOH terminal of the bioconjugates. The interaction of ENaC with anti-ENaC on the bioconjugates was detected by differential pulse voltammetry using a ferricyanide redox system. The assay was optimized using a Box-Behnken experimental design. The result shows that SPCE/Au increased the peak current signal of [Fe(CN)6]4−/3- by 10-fold compared to SPCE bare. Scanning electron microscope analysis revealed that the surface of the modified electrodes has become rougher. The detection and quantification limit of the immunosensors were 8.4 × 10−2 ng/mL and 2.8 × 10−1 ng/mL, respectively, within the range of 9.375 × 10−2 to 1.0 ng/mL of ENaC. Detection of ENaC in urine samples showed high recovery, suggesting that the designed electrochemical immunosensor can be used as a simple and fast alternative method to determine the ENaC in urine samples.

Keywords

• Bioconjugate
• Epithelial sodium channel (ENaC)
• Immunosensor
• Screen-printed carbon electrode
• Hypertension