Highly efficient bienzyme functionalized biocompatible nanostructured nickel ferrite-chitosan nanocomposite platform for biomedical application

A new hybrid nanocomposite based on hydrothermally synthesized nanostructured NiFe₂O₄ (n-NiFe₂O₄) and chitosan (CH) has been explored for bienzyme (cholesterol esterase (ChEt) and cholesterol oxidase (ChOx)) immobilization for application as total cholesterol biosensor. Results of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Raman spectroscopy (RS) and vibrating sample magnetometer (VSM) studies demonstrate that the ChEt-ChOx/n-NiFe₂O₄-CH composite film is successfully synthesized. The obtained ChEt-ChOx/n-NiFe ₂O₄-CH nanocomposite film shows large specific area, high conductivity, good biocompatibility, fast redox properties and improved antimicrobial activity. The fabricated ChEt-ChOx/n-NiFe₂O ₄-CH/ITO bioelectrode exhibits largely improved amperometric biosensing performance, i.e., good linearity (5-400 mg/dL), low detection limit (24.46 mg/dL cm^-2), high sensitivity of 1.73 μA/(mg/dL cm ^-2), fast response time of 15s, reproducibility of more than 15 times, shelf life of about 90 days and low Michaelis-Menten constant (K _m) value as 7.05 mg/dL (0.1825 mM). Furthermore, this modified bioelectrode has been utilized for estimation of total cholesterol in human serum samples. This efficient strategy provides new insight into the design of novel flexible electrodes for a wide range of applications in biosensing, bioelectronics, and clinical applications.