Development of (bio)sensor for spermine and spermidine determination

In this investigation, the immobilization of diamine oxidase (DAO) enzyme onto modified screen-printed carbon electrodes (SPE), subsequently coated with Nafion (NF) and incorporating Co3O4 nanoparticles, as well as carboxylated and carboxyl-free multi-walled carbon nanotubes (c-MWCNT and MWCNT), was undertaken for the precise determination of spermine and spermidine. The quantities of Co3O4 nanoparticles and multiwall carbon nanotubes for electrode modification were systematically optimized using a central composite design. The optimal quantity of DAO enzyme was identified as 0.005 U. The study elucidated the optimal working conditions and performance characteristics of the developed biosensor. The calibration sensitivity of the NF/DAO/c-MWCNT-Co3O4NP/SPE biosensor was determined to be 51.6 µA/mM for spermine and 15.7 µA/mM for spermidine. The linear working range spanned from 1.2×10-6 to 2.6×10-4 M for spermine and 1.9×10-6 to 1.8×10-3 M for spermidine, with a limit of detection of 4.4×10-7 M for spermine and 1.6×10-6 M for spermidine. Through the design of the NF/DAO/MWCNT-Co3O4NP-PM/SPE mediated biosensor, the objective was to enhance selectivity at lower potentials and minimize interference effects from similar species. The sensitivity of the NF/DAO/MWCNT-Co3O4NP-PM/SPE biosensor was determined to be 11.2 µA/mM for spermine and 9.7 µA/mM for spermidine, with a linear working range extending from 5.0×10-6 to 1.5×10-4 M for spermine and 1.2×10-6 to 8.4×10-5 M for spermidine. The limit of detection for this biosensor was observed as 4.2×10-6 M for spermine and 1.7×10-6 M for spermidine. Furthermore, the NF/DAO/c-MWCNT-Co3O4NP/SPE biosensor demonstrated a recovery of %(100.5 ± 1.7) for spermine and %(100.8 ± 1.9) for spermidine in malt beverage.