Electrochemical Label-Free Immunosensor for The Detection of Epithelial Sodium Channels Using Gold Modified Screen-Printed Carbon Electrode

The epithelial sodium channel (ENaC) is a protein used in maintaining sodium levels and related to hypertension. ENaC protein is abundant in lung, gut, and kidney. An electrochemical immunosensor has developed to detect the level of ENaC in the urine. The electrode used was screen printed carbon electrode-gold (SPCE-Au) via HAuCl4 electrodeposition. Anti-ENaC was immobilized onto the SPCE-Au with 3-mercaptopropinonic (MPA) linker between gold and anti-ENaC. Various concentration of standard ENaC was used to determine the optimum experiment condition and analytical parameters. The interaction of Anti-ENaC that immobilized on the electrode surface with ENaC was measured as a ferric cyanide response by differential pulse voltammetry. The SPCE-Au has increased the ferric cyanide peak current by about 482% compare to SPCE bare. Immobilization of the Anti-ENaC decreases the peak current of about 53%. The optimum conditions of the experiment were obtained; 0.01 M of MPA for 20 min incubation time, and 0.5 µg/mL of anti-EnaC concentration. The sensitivity of the immunosensor was 10.571, the limit of detection of 0.037 ng/mL, and the limit of quantification 0.123 ng/mL for ENaC concentration range from 0.1 to 1.5 ng/mL. Furthermore, the proposed immunosensor can be used to measure the concentration of ENaC as a biomarker of hypertension in clinical urine samples.