Pure Organic Phase Phenol Biosensor Based on Tyrosinase Entrapped in a Vapor Deposited Titania Sol‐Gel Membrane

Abstract

A novel amperometric biosensor was constructed for the determination of phenols in pure organic phase. This biosensor was fabricated by immobilizing tyrosinase in a titania sol-gel membrane which was obtained with a vapor deposition method. This method was facile and avoided the calcination step needed in conventional titania sol-gel process. The titania sol-gel membrane could effectively retain the essential water layer around the enzyme molecule needed for maintaining its activity in organic phase. The experimental parameters such as solvent and operating potential were optimized. At À 100 mV this biosensor showed a good amperometric response to phenols in pure chloroform without any mediator and rehydration of the enzyme. For catechol determination the sensor exhibited a fast response of less than 5 seconds. The sensitivity of different phenols was as follows: catechol > phenol > p-cresol. Additionally, the apparent Michaelis-Menten constants of the encapsulated tyrosinase to catechol, phenol and pcresol were found to be 0.15 AE 0.003, 0.17 AE 0.008 and 0.21 AE 0.004 mM, respectively. The biosensor had also good reproducibility and stability. This work provided a promising platform for the construction of pure organic phase biosensors and the determination of substrates with poor water solubility.

Amperometric Hydrogen Peroxide Biosensor Based on Horseradish Peroxidase Entrapped in Titania Sol-Gel Film on Screen-Printed Electrode

“…On the other hand, the ability of amino acids presented at the active sites of the enzyme to interact with the substrate depends on their electrostatic state, which in turn depends on the pH of the solution; thus optimization of the working pH for the enzyme electrode is considered to be important [50]. The ionization states of the charged groups of enzymes that retained their ionizations from the last solution to which they have been exposed are influenced by the pH value of the last aqueous solution [42]. The dependence of the biosensor response on pH of the measurement solution was investigated.…”

“…The enzyme, as a biocatalyst, loses its ability without the existence of water, and no response can be seen in this condition. Then Titania sol-gel membranes maintain water that is stored within the adjacent layers of enzyme [42]. In this work, we attempted to report on a novel platform based on flexible polyethylene terephthalate (PET) substrate in order to design a high-performance electrochemical screen-printed biosensor.…”

Organic phase enzyme electrodes

“…Yu and Ju (2004) determined phenols in pure chloroform by immobilizing PPO in a titania sol-gel membrane obtained with a vapour deposition method. No extra water was required, because the titania sol-gel membrane retains the essential water layer needed for maintaining the enzyme activity in the organic phase, thus providing a promising platform for the construction of pure organic phase biosensors (Yu and Ju, 2004).…”

Co-Immobilization of Peroxidase and Tyrosinase onto Hybrid Membranes Obtained by the Sol-Gel Method for the Construction of an Optical Biosensor

“…enzyme biosensors are a potential alternative to these methods. A number of biosensors have been designed for detecting phenols by immobilization of tyrosinase; among them the amperometric, potentiometric (28) and optical sensors (1,8) are prevailing.…”