Noninvasive Electrochemical Nitric Oxide Detection in Human Saliva Using Pt and TiO₂ Nanoparticle Composite Electrodes

Abstract

Nitric oxide (NO) plays major roles in various physiological processes, such as neurotransmission, vasodilation, blood pressure monitoring, and immune response. Precise regulation of NO concentration in our body can be measured as a potential biomarker for numerous diseases such as hypertension, diabetes, Parkinson’s disease, ischemia, and rheumatoid arthritis. In this report, an electrochemical NO sensor was fabricated using a nanocomposite material consisting of Pt and TiO 2 nanoparticles (Pt-TiO 2 NPs). Pt and TiO 2 nanoparticles were synthesized using the sol–gel method. NO sensing measurements were carried out using a Pt-TiO 2 NPs-modified glassy carbon (GC) electrode after adding various concentrations of NO. The nanoparticles-modified GC electrode demonstrated high sensitivity (∼7.81 μA mM –1 cm –2 ) in a wide linear detection range (∼10 nM to 17.79 mM). The sensor exhibited a very low detection limit (∼2.47 nM), high stability, and excellent selectivity toward NO. NO detection using a Pt-TiO 2 NPs-deposited screen-printed carbon electrode was also studied in detail. Such a highly sensitive and selective sensor has been employed for noninvasive NO detection in human saliva.