Determination of H₂O₂ and its antioxidant activity by BCM@Au NPs ratiometric SERS sensor

As a reactive oxygen species (ROS), excessive production of H₂O₂ contributes to the development of several diseases such as, inflammation, cancer, and respiratory diseases. Supplementation with endogenous or exogenous antioxidants can scavenge ROS and reduce the oxidation of cellular molecules, thus alleviating the generation of diseases. Therefore, the determination of H₂O₂ content and its antioxidant activity is of great importance in disease diagnosis and treatment. In this paper, a ratiometric SERS sensor with a flexible cellulose membrane was designed for quantitative detection of H₂O₂ and assessment of antioxidant activity. First, gold seeds were reduced on bacterial cellulose membrane (BCM) and Au NPs were smoothly deposited on the bacterial cellulose membrane (BCM) using halides to reduce the reduction potential in the growth solution to form a flexible BCM@Au NPs SERS substrate. Afterwards, the oxidation of H₂O₂ was used to convert 3-mercaptophenylboronic acid (3-MPBA) to the corresponding phenol form 3-hydroxyphenylethanol (3-HTP). The change of substance resulted in a good linear relationship between the intensity ratio corresponding to the two Raman shifts of 881 cm^-1 and 995 cm^-1 and the H₂O₂ concentration with a detection limit of 0.0186 μM. This opens up a new method for the detection of H₂O₂ with high sensitivity and accuracy. In addition, this SERS platform was successfully used for the determination of antioxidant activity. It is promising to be applied to disease diagnosis and efficacy evaluation.