Using concanavalinA as a spacer for immobilization of E. coli onto magnetic nanoparticles.

ConcanavalinA (conA) is a protein extracted from the concanavalin, which has specific recognition through mannose components on bacterial cell surfaces. A magnetic nanocarrier with the structure of a dopamine functionalized magnetic nanoparticles was grafted with conA, and was used for immobilization of recombinant Escherichia coli harboring glycerol dehydrogenase with the specific recognition between glycoconjugates and glycoprotein. The effect of various factors on the immobilization including temperature, pH, cell concentration and immobilization time were investigated. The highest immobilization yield of 91% was obtained under the conditions: enzyme/support 1.28mg/mg, pH 8.0, immobilization time 2h and temperature 4°C. The obtained immobilized cell was characterized and exhibited higher thermal stability compared with the free cell. After ten cycles, the immobilized cell remained 62% initial activity. These results indicate that the cell immobilized onto conA-grafted nanoparticles by specific recognition of glycoconjugates and glycoprotein is a potential method for preparation of stable cell, and the immobilized cell showed perspective applications in the biocatalysis and biosensors.