Non-Enzymatic Urea Sensing Based on MWCNT Nanocomposite

In this work, we have demonstrated a urea sensor based on starch coated gold nanoparticles (S-AuNPs) and thiol group (-SH) functionalized multiwall carbon nanotube (MWCNT-SH) nanocomposite. The surface modifications of the MWCNTs are characterized using Fourier transform infrared (FTIR) and Raman spectroscopy. The surface analysis of the nanocomposite is recorded using field emission scanning electron microscope (FESEM) and field emission transmission electron microscope (FETEM). The sensor is developed on a glass substrate where silver and MWCNT-SH/S-AuNPs are used as contact electrodes and sensing material, respectively. The response of the sensor is observed over a range between 10 mg/dL to 60 mg/dL with high sensitivity and limit of detection of 0.48 mg/dL. The sensor has demonstrated almost stable performance for two months with excellent reproducibility. The developed sensor is evaluated to detect urea in a raw milk sample, where the sensor can recover urea between 85.17% and 88.73% in the milk sample. The proposed sensor has the potential to be used for milk quality assessment in households and dairy industries.