Organophosphonate functionalized Au/Si@Fe₃O₄: Versatile carrier for enzyme immobilization

Magnetic nanoparticles with silica/gold (Au) shell were synthesized to be used as substrates for enzyme immobilization. Successful functionalization was followed by addition of phosphate linkers containing carboxyl end as free end for linking with enzyme. Effect of varied phospho-carboxyl chain lengths based linkers, 3-phosphonopropionic acid (3-PPA) and 16-phosphonopropionic acid (16-PHDA) on kinetic parameters of enzyme were studied. Immobilization of upto 670μg/mg of nanoparticles were observed. Enzyme bound with longer chain linker were observed to have K_m (11.8mg/mL) and V_max (1.59μmol/min/mg) which was found to be lower than 3-PPA. Reusability assay gave a minimum of 70% activity at 10th time of usage. Thus, an efficient, robust, cost effective and easily separable substrate for restraining the enzyme was prepared.