High-performance amperometric determination of nitric oxide released by endothelial cells using flow injection analysis

An amperometric flow injection analysis (FIA) method based on an optimized carbon paste electrode (CPE) for the determination of nitric oxide (NO) production from endothelial cells (ECs) was developed. The CPE was modified by Nafion, gold nanoparticles (AuNPs) and graphene nanoribbons (GNRs) via drop casting method. The proposed sensor exhibited excellent sensitivity and selectivity to the oxidation of NO with a linear correlation of 0.02 -22.4 mu M and a detection limit of 6 nM. The developed method is applied for real-time measurements of NO released from endothelial cells by stimulation of endothelial NO synthase (eNOS). Induction of NO synthesis by eNOS was successfully initiated by the calcium ionophore A23187, acetylcholine (ACh), or L-arginine. Furthermore, a reduction of eNOS activity could be observed after the addition of a NOS inhibitor, resulting in a decrease in NO signaling. Targeting eNOS could be of considerable value with regard to preventing or treating the development of cardiovascular diseases. The sensor's ease of fabrication and applicability for cell mea-surements enables the device to be used in pharmacological research and drug discovery.