Amperometric biosensors based on LDH-ALGINATE hybrid nanocomposite for aqueous and non-aqueous phenolic compounds detection

To immobilize enzyme a new elegant approach based on layered double hydroxide–alginate hybrid nanocomposite (Zn2Al–Alg LDH) was developed for fabricating phenol biosensors. The alginate biopolymer was intercalated into the LDH structure by the direct coprecipitation method, and the resulting nanohybrid material was applied to entrap polyphenol oxidase (PPO). Interactions between PPO and LDH–Alg were characterized by PXDR, FT-IR and SEM. These biomembranes were stabilized by chemical cross-linking with glutaraldehyde (GA) or calcium complexation and subsequently were tested for the detection of phenol derivatives in Tris–HCl buffer (pH 7.0) and organic solvents. In aqueous medium, the best configuration was PPO/Zn2Al–Alg/GA which exhibited a very high sensitivity for catechol, namely 73.6 A M−1 cm−2 over a linear range between 2 × 10−9 and 3 × 10−5 M and with a detection limit of 0.5 nM. In chloroform, the PPO/Zn2Al–Alg/GA/Ca biomembrane had a linear response for catechol between 1 × 10−8 and 3 × 10−6 M with a sensitivity of 4.9 A M−1 cm−2 and a detection limit of 0.01 μM.