Electrochemical biosensor for assessment of the total antioxidant capacity of orange juice beverage based on the immobilizing DNA on a poly l-glutamic acid doped silver hybridized membrane

An electrochemical DNA damage biosensor for assessment of the antioxidant capacity in orange juice beverage was fabricated. The biosensor was constituted with a hybridized membrane of poly l-glutamic acid and Ag and an outside layer of chitosan (CS)/double stranded DNA (ds-DNA). The Fenton solution (Fe2+/H2O2) was used to generate hydroxyl radical (OH) and induce ds-DNA damage. The orange juice beverage and ascorbic acid (AA) could scavenge OH and protect ds-DNA from damage effectively. Based on this, the antioxidant capacities of the orange juice beverage and AA were studied by linear sweep voltammetry using Ru(NH3)63+ as indicator. The ultraviolet visible absorption spectrometry was also used to detect the ds-DNA damage and the antioxidant capacity with almost the same conclusions as the electrochemical method. The proposed biosensor exhibited good stability and reproducibility and was suitable for the assessment of the antioxidant capacity in beverages.