Chitosan/Fe3O4/graphene nanoplatelets composites-modified glassy carbon electrode for highly sensitive electrochemical detection of dopamine, uric acid, and ascorbic acid.

Chitosan (CS) is a cationic linear polysaccharide rich in functional groups (-OH and -NH2) that enable diverse biochemical interactions, making it a promising candidate for the electrochemical detection of dopamine (DA), uric acid (UA), and ascorbic acid (AA). However, its poor electrical conductivity and limited thermal stability restrict its standalone performance, thus requiring the formation of composites with other materials. In this study, we report the synthesis of a chitosan/Fe3O4/graphene nanoplatelet (CS@Fe3O4/GNP) nanocomposite for the highly sensitive and selective electrochemical detection of DA, UA, and AA. The nanocomposite integrates the superior conductivity and high surface area of GNP, the electrocatalytic activity of Fe3O4 nanoparticles, and the biocompatibility and adhesive nature of chitosan. The CS@Fe3O4/GNP composite with various CS concentration (0.0625, 0.125, and 0.25%) was synthesized via a facile in-situ co-precipitation method. Electrochemical studies demonstrated that the 0.25% CS@Fe3O4/GNP-modified glassy carbon electrode (GCE) exhibited excellent detection performance toward DA, UA, and AA, with limits of detection (LOD) of 28.37 nM (range 30-488 nM), 566.27 nM (range 0.98-15.6 μM), and 26.54 μM (range 31.25-500 μM), respectively. The sensor also achieved recovery rates of 87.83-92.68% (DA), 82.41-91.61% (UA), and 88.83-95.04% (AA) in human blood serum samples.