Low-temperature and iron-doping to tailor Nannochloropsis Oceanica-derived carbon for high-performance dopamine biosensing

Nannochloropsis Oceanica ( N. Oceanica ), widely distributed across global marine environments, is rich in proteins and amino acids, serving as an excellent source of nitrogen self-doped biomass carbon. Further modification and optimization of this microalga for constructing high-performance sensing platforms hold significant research and practical implications. This study strategically employs iron doping during low-temperature carbonization to modulate the structural and electronic properties of N. Oceanica -derived carbon. Results demonstrate that varying iron concentrations greatly accelerates graphitization, tailors the pore architecture, and significantly increases the specific surface area, thereby creating abundant catalytic active sites. The optimized iron-doped carbon material serves as a highly effective electrocatalyst when integrating into silk fabric-based screen-printed electrodes. These biosensors achieve exceptional dopamine (DA) detection performance, featuring a remarkably low detection limit (3 nM) and a broad linear range (0.01–2000 µM). Crucially, mechanistic analysis reveals that iron facilitates electrocatalytic activity and significantly enhance charge-transfer efficiency, thereby significantly boosting catalytic ability. This work establishes a novel, low-temperature iron-doping strategy for transforming biomass carbon into a cost-effective, eco-friendly, and high-performance platform for flexible electrochemical DA biosensors, paving a way for advanced bioanalytical applications.