Figure 5. Applications of photochromic carbon-based nanomaterials in sensing (upper images) and biology (lower image).

(a) CNTs modified with azobenzenes were used as a color detector. Reproduced from ref. 100 (Copyright 2009 American Chemical Society, http://pubs.acs.org/doi/pdf/10.1021/nl8032922). (b) Spiropyrans covalently attached to CNTs were used to regulate horseradish peroxidase (HRP) activity via light irradiation. Reproduced from ref. 110 (Copyright 2011 Royal Society of Chemistry). (c) rGO/hyaluronic acid-spiropyran used for in vivo fluorescence imaging. Adapted from ref. 114 (Copyright 2013 American Chemical Society).