Poly(Amic Acid)/Clay Nanocomposites Based on 4,4′-Oxydianiline-Modified Montmorillonite for Catalase Immobilization and Electrochemical Detection of H2O2

Polymer/clay nanocomposites have gained significant attention in recent years owing to their exceptional physical and mechanical properties, which fulfill critical needs in the fields of biotechnology, environmental technologies, and electronics. In this study, nanocomposites composed of poly(amic acid) (PAA) and montmorillonite (Mt) were prepared via an in situ polymerization method, which was then used as an immobilization matrix for catalase (Cat) in enzyme biosensor. PAA/Mt nanocomposites were synthesized using 4,4 '-oxydianiline (ODA) and pyromellitic dianhydride (PMDA) monomers within the montmorillonite layers at different clay loading degrees. Morphological and structural characterizations of the PAA/Mt were performed using FTIR, XRD, SEM, TEM, and TGA methods. Applicability of the characterized PAA/Mt/Cat sensing platform was evaluated for the detection of hydrogen peroxide (H2O2), for which 0.125-3.75 mu M was determined as the linear detection range with 0.017 mu M limit of detection (LOD). No significant interference effect (D-glucose, bovine serum albumin, insulin, ethanol, CRP, A.acid, Na+, Mg2+, and Ca2+) was observed on the current signal for H2O2, and real sample application of the sensing platform was successfully shown using artificial serum, sweat, and urine with % spike recovery.