Peroxidase mimetic activity of Fe₃O₄ nanoparticle prepared based on magnetic hydrogels for hydrogen peroxide and glucose detection

Stimuli-response magnetic hydrogels were prepared in the mixtures of magnetic surfactants, (C_nTAFB(C), n=12, 14, 16), and chiral amphiphiles, sodium cholate (SC). The gelation behavior of C_nTAFB(C)/SC were studied in detail. The results proved that the hydrophobicity of surfactants and the hydration radius (R_h) of anions played a vital role in the gelation process. The microstructure of the hydrogels were determined to be three-dimensional network of fibrous aggregates. The formation of the hydrogel fibrils was considered to be mainly driven by a delicate balance of multiple non-covalent interactions including hydrophobic interaction, electrostatic interaction, hydrogen bonding, van der Waals force, and the steric effect of SC molecule. Rheological measurements demonstrated that the hydrogels are high mechanical strength materials (the yield stress exceeding 2000Pa). The mechanical strength of the hydrogels is dependent on the fiber density, which can be regulated by changing the proportion of the two compounds, the total concentration and the chain length of the surfactants. The magnetic hydrogels of C₁₂TAFB/SC mixtures served as the precursors for preparing cubic Fe₃O₄ nanoparticles with the diameter of 7.2nm. The as-prepared Fe₃O₄ nanoparticles exhibit excellent ferromagnetic characteristic and high peroxidase-like activity and can be used as biosensor for hydrogen peroxide (H₂O₂) and glucose detection. We developed a convenient and green method for preparing Fe₃O₄ nanoparticles, which can be used as a promising candidate biosensor for glucose detection.