Biocompatible gelatin/carbon dot nanocomposite based urea sensor and the effect of nitrogen ion implantation

In this study, we have fabricated a novel platform for sensing of urea using gelatin/carbon dots nanocomposite system. The sensor electrode was created by depositing the nanocomposite gel onto thin glass plates coated with indium tin oxide (ITO) using the drop casting technique. The behavior of these electrodes was investigated against a number of bioanalytes in the concentration range of 2-20 mM by cyclic voltammetry. The system was observed to be highly selective for urea with a sensitivity of 1.65 μA/mM/cm in the experimental linear range of 2-20 mM. Furthermore, the gelatin/CD-ITO electrode were also subjected to 50 KeV N₂⁺ ion beam irradiation with varying fluence in the range of 10¹² to 10¹⁶ ions/cm². Sensing profile of the irradiated samples for urea suggested enhancement in sensitivity to 2 μA/mM cm², when the ion fluence was 5 × 10¹⁵ ions/cm². This enhancement after irradiation suggests a clear dependence of detection on the fluence of the ion beam. The observed excellent sensitivity of radiation processed nanocomposite material can be used as an enzyme-free platform for urea detection. Additionally, the CDs showed fluorescence quenching on treatment with mere 50 μM urea suggesting the high sensitivity of the platform.