NiO-decorated cocoon silk-derived carbon-based non-invasive electrochemical sensor for detecting glucose in saliva

To enhance the quality of life for individuals with diabetes, groundbreaking researches for non-invasive sensors were devised, capable of monitoring glucose levels in saliva. Herein, cocoon silk was first pyrolyzed and acid-treated, following by the decoration of NiO nanoparticles under calcination method. The activated carbon exhibits excellent electrocatalytic properties owing to the inherent presence of heteroatoms within the cocoon silk, specifically nitrogen and oxygen. The synergetic effect of NiO nanoparticles and cocoon silk-based carbons improves the electron transfer rate and enhances the electrocatalytic activity toward the detection of glucose. This enzyme-free glucose sensor shows the sensitivity of 74.24 μA mM⁻¹ cm⁻², the wide linear range from 1 to 3300 μM, and the low detection limit of 0.28 μM. Furthermore, the sensor demonstrates good selectivity, repeatability, and stability. Importantly, it is able to detect the glucose levels in real human saliva without pretreatment, exhibiting great potentials in the application of non-invasive sensors.