LAUSR

Abstract Graphene oxide (GO) has broad application prospects in the field of catalysis, especially as enzyme carrier, owing to its unique intriguing physic-chemical properties. In this paper, the layer structure and oxygen functional group content of GO which may affect the properties of the immobilized enzyme were discussed. GO was prepared from 8000 mesh and nanoscale graphite at different reaction temperatures (40 °C and 95 °C), and used as carriers to immobilize α-amylase by deposition and cross-linking methods, respectively. Several analytical tools, including AFM, FT-IR, UV–Vis, XPS, and Raman, were used to character GOs. The enzyme loading of GO-8000-40 °C-E (of GO-NM-95 °C-GA-E) was 122.1 (49.8) mg/g, which retained 94.7 (82.6) % of the free enzyme activity, the optimum pH, optimum temperature, K m and V max were 7.0 (7.0), 70 (75) °C, 18.837 (39.989) mg/mL and 1.584 (1.842) μmol/(mL·min), respectively. Overall results indicated that 8000 mesh graphite was suitable for the preparation of immobilized enzyme by deposition method, while nano-graphite had an advantage in cross-linking immobilized enzyme. Graphic Abstract