Immobilization of Papain onto Graphene Oxide Nanosheets

Graphene oxide nanosheets was prepared, functionlized with 3-aminopropyltriethoxysilane and used as the carrier for immobilization of papain. A high immobilization yield and efficiency higher than 80% were achieved at pH 8.0 and 35 °C. The thermal stability of the immobilized papain was improved compared with the free enzyme. And the immobilized papain retained about 63% of its initial activity after 30 days storage at 4 °C, while free enzyme was only 41% at the same conditions. The immobilized enzyme displayed higher binding affinity to substrate because of the unique properties of GO. These results indicate that modified graphene oxide nanosheets has a good potential as carrier for immobilization of proteins, especially enzymes.