Simple and Mediator-Free Urea Sensing Based on Engineered Nanodiamonds with Polyaniline Nanofibers Synthesized in Situ

In an effort to develop a simple and mediator-free sensing media for urea, a polyaniline (PANI) and graphitized nanodiamond (GND) nanocomposite was prepared at room temperature via an in situ interfacial polymerization approach. The interaction of ions produced during the hydrolysis of urea with nanomaterial was utilized for the amperometric sensing of urea. The performance of this composite (GND/PANI) was evaluated for the detection of urea referenced to PANI. Accordingly, both platforms exhibited good linearity across a varying concentration of 0.1 to 0.9 mg mL –1 with limit of detection (LOD) values of 0.07 (PANI) and 0.05 mg mL –1 (GNDs–PANI). As such, both of them were able to detect urea well below the common range in real samples. Moreover, their sensitivities were also determined as 140.5 and 381.5 μA (mg mL –1 ) −1 cm –2 with a response time of 15 and 20 s, respectively. As such, the incorporation of GND with PANI was helpful toward enhancement of sensitivity.