**3. Oriented Immobilization of Redox Enzymes in Modified Carbon Nanomaterials**

π Because the surface physiochemistry of carbon nanomaterials plays a key role in the orientation of redox enzymes, strategies for the rational surface modification of carbon nanomaterials to provide suitable platforms for DET-type bioelectrocatalysis of redox enzymes are highly expected. In general, functional groups at carbon nanomaterial surfaces can be introduced by different approaches, including diazonium electroreduction [46], amine electrooxidation [47], π-stacking [48], and *in-situ* chemical modification [49] (Figure 4). We do not discuss these approaches in detail herein, focusing instead on strategies to control the orientation of redox enzymes in modified carbon nanomaterials for enhanced DET-type bioelectrocatalysis. π

**Figure 4.** Typical strategies for surface modification of carbon nanomaterials. CNTs were utilized here as representatives of carbon nanomaterials.
