Nickel Hydroxide Nanoflake/Carbon Nanotube Composites for the Electrochemical Detection of Glutamic Acid using In Vitro Stroke Model

The significance of glutamic acid in healthcare as a neurotransmitter and food additive has prompted the scientific community to develop cost-effective non-enzymatic sensors with improved sensitivity, selectivity, and stability. Herein, we propose a non-enzymatic electrochemical sensor based on low-cost transition metal hydroxides to detect glutamic acid efficiently. An n-butanol/ water interface-assisted synthesis strategy was employed as an initial step to tailor two-dimensional nickel hydroxide nanoflakes. To further improve electrical conductivity, nickel hydroxide nanoflakes were composited with a small amount of highly conductive multiwalled carbon nanotubes to form NH/MWCNT composite. The NH/MWCNT composite-modified sensor demonstrated excellent detection of glutamic acid with a detection limit of 72 nM, even in the presence of many interfering groups. The practicality of the sensor in medical technology was established by its ability to detect glutamic acid released by SH-SY5Y neural cells in both normal and oxygen-glucose deprivation-stressed conditions. As an extended application, the proposed sensor was also demonstrated to detect monosodium glutamate, a food additive found in commercially available food products. Finally, as a proof of concept, an in-house flexible sensor was fabricated to monitor glutamic acid released by human neural cells and monosodium glutamate in food samples. We anticipate that the present work will contribute to the development of cutting-edge third-generation non-enzymatic sensors for glutamic acid monitoring.