Table 1.
Box-Behnken experimental design for independent variables and their corresponding response (% immobilization).
Figure 1.
Response surface and contour plots showing effects of various parameters on immobilization (%) and the predicted optimal response.
3D and contour plot for (a) the effect of amount of enzyme and concentration of glutaraldehyde on immobilization (%), (b) the effect of amount of enzyme and amount of functionalized graphene and (c) the effect of amount of functionalized graphene and concentration of glutaraldehyde on immobilization (%).
Table 2.
Analysis of variance (ANOVA) for response surface model pertaining to percent immobilization.
Figure 2.
Micrographs of functionalized graphene sheets and the sheets having enzyme immobilized on them.
(A) SEM images of (i) functionalized graphene sheets and (ii) enzyme immobilized on graphene sheets (B) TEM images of (i) functionalized grapheme sheets and (ii) immobilized enzyme with inset showing the selected area electron diffraction pattern.
Figure 3.
FTIR spectra of graphene sheets during different stages of immobilization.
FTIR spectra of (a) enzyme immobilized on graphene, (b) glutaraldehyde treated graphene and (c) functionalized graphene sheets.
Figure 4.
Kinetics, stability and reusability of immobilized enzyme.
Effect of pH (a) and temperature (b) on the activity of soluble and immobilized Fenugreek β-amylase (c) represents storage stability of soluble and immobilized Fenugreek β-amylase and (d) represents reusability (10 uses) of immobilized Fenugreek β-amylase.