Colorimetric visualization of superoxide dismutase in serum via etching of Au nanorods from superoxide radical

In this study, a visual approach for the colorimetric detection of superoxide dismutase (SOD) activity was developed through prohibiting the morphology transition of cetyltrimethylammonium bromide-stabilized Au nanorods (NRs). Superoxide radical (O 2 − ) generated from the reaction between H 2 O 2 and Fe 2+ would preferentially etch Au NRs along the longitudinal direction and result in remarkable changes of shape and the Longitudinal Localized Surface Plasmon Resonance absorption band of Au NRs. Thanks to the dismutation of SOD, SOD decomposed O 2 − into H 2 O 2 and O 2. Thus, the etching process was held back. Under optimal conditions, the sensor reveals excellent selectivity and sensitivity toward SOD (limited detection is 0.25 U). A linear detection range from 1.4 to 14 U was obtained. The proposed sensing system not only was applied in the serum media, but also was made to a kind of cost-effective sensory agarose hydrogel with vivid color changes.