Enzyme mimetic electrochemical sensor for salivary nitrite detection using copper chlorophyllin and carbon nanotubes-functionalized screen printed electrodes

Electrochemical detection of salivary nitrite (NO2-) is gaining importance in establishing screening protocols for identifying people with oral diseases and other clinical conditions associated with nitric oxide biology. This work demonstrates smart sensing of salivary NO2- levels through a point-of-care (POC) electrochemical approach. The electrochemical sensor was prepared using copper chlorophyllin (CuCP) as an enzyme mimic and electrodeposited onto multi-walled carbon nanotubes (MWCNTs)-functionalized screen-printed carbon electrodes. The morphology and composition of the nanocomposite-modified printed sensors were evaluated using field-emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical techniques such as cyclic voltammetry and linear sweep voltammetry were used to characterize the electrochemical sensor and measure the nitrite levels. The modified CuCP-MWCNTs-SPCE allowed the electrochemical sensing of nitrite over a wide range of concentrations (10 mu M to 10 mM) in standard and human saliva samples. The electrochemical activation of CuCP on MWCNTs enabled the sensitive detection of nitrite. The practical applicability of the enzyme mimic-based sensing platform was tested in real human saliva samples (n = 5) to enable POC measurement. The results of the electrochemical sensors are validated with a commercial Griess reagent test. Electrochemical detection of salivary nitrite (NO2-) is gaining importance in establishing screening protocols for identifying people with oral diseases and other clinical conditions associated with nitric oxide biology.