An optical-based biosensor of the epithelial sodium channel as a tool for diagnosing hypertension.

Arterial hypertension (HTN) is a world health concern presenting difficulties for its early detection. It leads to cardiovascular and kidney complications that increase morbidity in adults. Overexpression in the epithelial sodium channel (ENaC) in membrane platelets can be related with the presence of HTN and thus can be used as a biomarker to detect this medical condition. Here, we propose a method for HTN diagnosis based on gold nanoparticles (GNPs) conjugated to an antibody against the ENaC present on platelets. These functionalized GNPs were analyzed by Zeta potential, dynamic light scattering, electron microscopy, and other spectroscopic techniques. To verify that the GNPs and α-ENaC antibodies formed conjugates (GNPs-antiENaC) that maintained their specificity to the target, we carried out an indirect immunofluorescence detection assay of GNPs-antiENaC bound to a secondary antibody labeled with a fluorophore. Our results show that the presence of GNPs increase the fluorescence intensity in platelets treated with GNPs-antiENaC conjugates. It is also observed a clear tendency of the fluorescence signal in platelets treated with the conjugates that could be used for discrimination between normotensive and hypertensive samples. The proposed assay can be implemented as a very sensitive routine test to diagnose HTN.