An enhanced L-lactate biosensor based on nanohybrid of chitosan, iron-nanoparticles and carboxylated multiwalled carbon nanotubes

An enhanced biosensor was developed for the determination of blood lactate in lacto-acidosis patients. The biosensor employed a nanohybrid composed of chitosan/iron oxide nanoparticles and carboxylated multiwalled carbon nanotubes (CHIT/Fe₃O₄NPs/c-MWCNTs), electrodeposited onto an Au electrode, followed by covalent immobilization of L-lactate oxidase (LOx) onto this nano-hybrid. The biosensor (LOx/CHIT/Fe₃O₄NPs/c-MWCNTs/AuE) exhibited notable improvements in its analytical characteristics such as a rapid response time (4s), a lower detection limit of 0.15 μM and a wider linear range of 1–3000 μM of L-lactic acid. Additionally, it displayed enhanced reproducibility and an extended shelf life of 100 days. The biosensor was employed to measure the concentration of L-lactate in the plasma of both apparently healthy individuals and lacto-acidosis patients. The results showed that the L-lactate concentrations ranged from 112 ± 1.24 to 183 ± 29.15 μmol/L in apparently healthy individuals, whereas it ranged from 2236 ± 33.29 to 4949 ± 72.39 μmol/L in lacto-acidosis patients, which is significantly higher than in apparently healthy individuals. Thus, the integration of the CHIT/Fe₃O₄NPs/c-MWCNTs hybrid film in the biosensor led to the enhanced analytical performance of the biosensor.