Development of an Enzymatic Biosensor Using Glutamate Oxidase on Organic–Inorganic-Structured, Electrospun Nanofiber-Modified Electrodes for Monosodium Glutamate Detection

Herein, dendrimer-modified montmorillonite (Mt)-decorated poly-Ɛ-caprolactone (PCL) and chitosan (CHIT)-based nanofibers were prepared. Mt was modified with a poly(amidoamine) generation 1 (PAMAM(G1)) dendrimer, and the obtained PAMAM(G1)–Mt was incorporated into the PCL–CHIT nanofiber’s structure. The PCL–CHIT/PAMAM(G1)–Mt nanofibers were conjugated with glutamate oxidase (GluOx) to design a bio-based detection system for monosodium glutamate (MSG). PAMAM(G1)–Mt was added to the PCL–CHIT backbone to provide a multipoint binding side to immobilize GluOx via covalent bonds. After the characterization of PCL–CHIT/PAMAM(G1)–Mt/GluOx, it was calibrated for MSG. The linear ranges were determined from 0.025 to 0.25 mM MSG using PCL–CHIT/Mt/GluOx and from 0.0025 to 0.175 mM MSG using PCL–CHIT/PAMAMG(1)–Mt/GluOx (with a detection limit of 7.019 µM for PCL–CHIT/Mt/GluOx and 1.045 µM for PCL–CHIT/PAMAMG(1)–Mt/GluOx). Finally, PCL–CHIT/PAMAMG(1)–Mt/GluOx was applied to analyze MSG content in tomato soup without interfering with the sample matrix, giving a recovery percentage of 103.125%. Hence, the nanofiber modification with dendrimer-intercalated Mt and GluOx conjugation onto the formed nanocomposite structures was performed, and the PCL–CHIT/PAMAM(G1)–Mt/GluOx system was successfully developed for MSG detection.