Portable sensitive and selective biosensing assay of dopamine in live cells using dual phosphorus and nitrogen doped carbon urchin-like structure

Portable sensors for detecting biomolecules have been widely applied in designing a new generation of clinical and biomedical devices. A portable sensor-based device was designed to integrate the interdigitated electrode array (IDA) decorated by dual phosphorus and nitrogen doped carbon urchin-like (P-, N-doped CU) structure. The morphological structure, surface nature of porosity and surface area, and electrochemical sensing property to signaling dopamine (DA) molecules of P-, N-doped CU were investigated under various annealing temperatures and activation. The P-, N-doped CU-800 K showed the best active surface materials with urchin-like round shape morphology covered by nano-dendritic ends. The outer surface with a rough texture of connected nano-dendrites formed multiple grooves, U-undulates, and a high mass-to-volume ratio that facilitated molecular diffusion and increased the loading of DA molecules on the active electrode surface. The P-, N-doped graphitic carbon chain produced a functionalized surface with N and P groups creating several plane edge defects and enriching the surface by massive negative charges. These intrinsic features formed an active interfacial surface with fast electron diffusion, low surface charge resistance, high loading, and strong binding to DA molecules. The P-, N-doped CU-800 K/IDA showed high sensitivity (4461.4 µA/µM × cm²), low detection limit of 0.1 nM, wide linear range of 0.01 – 0.5 µM, good selectivity, high stability, low cytotoxicity, and biocompatibility. Therefore, the designed portable sensor of P, N-doped CU-800 K/IDA can be used for on-site detection of DA secreted from the human neuronal cell line model (SHSY-5Y) with a high sensitivity.