Surface modification to overcome diffusion limitations a study in urease immobilized magnetite nanoparticles

Abstract

Applications of enzymes are broadened with enhancement of stability and activity through immobilization techniques. At recent, nanomaterials are mostly involved as carriers for immobilization because of the unique properties like high surface area to volume ratio, inertness, higher stability and reactivity. An effective catalytic reaction involves strong interaction between enzyme and substrate. Also, immobilization not only improves the enzyme stability, but is also accompanied by the diffusion limitations. Notably, the surface properties are immediately linked to the diffusion processes in the reaction. Hence great attention on the surface of the nanocarriers is mandatory. In spite of higher enzyme loading on porous nanocarriers due to numerous binding sites for the enzyme, more diffusion limitations, textural changes and unequal enzyme distribution are caused. Surface modification of the nanocarriers remains compulsory for increased enzyme activity by overcoming the diffusion limitations. Therefore, the ultimate aim of this research is to study the diffusion limitations in the catalytic reaction performed by an enzyme immobilized onto nanocarriers. In the present study of diffusion limitations, the magnetite nanoparticles (MNs) and urease were chosen to be the model carrier and enzyme respectively. MNs were synthesized by the facile solvothermal method and the amino groups to facilitate enzyme binding was introduced by (2-aminoethyl) -3-aminopropyldimethoxymethylsilane (AEAPS). Surface modification was performed using the and#946;-Chitosan extracted from the squid pens, a feather shaped structure in squid species. Urease was immobilized onto the amino tagged MNs (aMNs) and the surface modified MNs (MNand#946;) after glutaraldehyde activation. newline