Prominent Study on Surface Properties and Diffusion Coefficient of Urease-Conjugated Magnetite Nanoparticles.

Herein, the magnetite nanoparticles (MNs) were prepared by facile solvothermal method and its porous nature was modified using 3-(2-aminoethyl)-3-aminopropyl trimethoxysilane (AEAPS). Magnetite formation, successful amino tagging, and urease conjugation on the surface were confirmed from the presence of certain functional groups in Fourier transform infrared (FT-IR) spectra. Also, nanosize (13.2 nm) and spherical morphology of MNs were evaluated from diffraction patterns and electron micrographs respectively. Lower retentivity and coercivities in magnetization curve revealed the superparamagnetic behavior, and nitrogen adsorption/desorption curves exhibited decrease in its surface porosity. Conductivity measurements showed lower diffusion coefficient (De  = 1.9 × 10-17  cm2 /min) and higher diffusion with limited hydrolytic reaction in native urease and improved activity of conjugated urease with higher De (12.62 × 10-16  cm2 /min). Hence, this study revealed that the surface porous nature of MNs can be altered effectively by amino tagging in order to overcome diffusional limitations thereby enhancing enzyme activity.