Purple to Yellow Silicone Elastomers: Design of a Versatile Sensor for Screening Antioxidant Activity

Antioxidants play a key role in counteracting the adverse effects of oxidative stress in human organisms. Thus, there is a huge demand for the development of smart and convenient assays for the evaluation of antioxidant activity of synthetic and natural compounds, food samples, plant extracts, etc. The design of a solid‐state, flexible, and portable format of the traditional in vitro 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical test is reported. For the first time, purple DPPH radicals are physically immobilized into a silicone matrix by means of a facile and rapid process. The working principle of the resulting sensor is based on the colorimetric process that is associated with the redox reaction of DPPH radicals with antioxidants. When an antioxidant reacts with the sensor, a color change from purple to yellow can be perceived by the naked eye. The response of the sensor is investigated qualitatively and quantitatively toward food samples and selected antioxidants of different natures, and solubilized in different media. It is demonstrated that the DPPH silicone sensor is highly versatile and can be used as a ready‐to‐use sensor for direct colorimetric detection of antioxidants.