Hydrogen Peroxide Biosensors Based on Horseradish Peroxidase and Hemoglobin

Hydrogen peroxide (H2O2) plays a pivotal role in various industrial applications [1]. It is an essential mediator in pharmaceutical, clinical, and environmental research. In addition, it is a byproduct of highly selective oxidases and an important contaminant in several industrial products and wastes [2]. Therefore, a reliable and economical method for the determination of H2O2 is of great significance. Several methods, such as titrimetry [3], spectrometry [4], chemiluminescence [5], fluorimetry [6], chromatography [7], and electrochemical techniques [8,9], have been reported for this purpose. Among these techniques, the electrochemical techniques are preferable because of their simplicity, low cost, high sensitivity, and selectivity [10-16]. In particular, an amperometric biosensor is an attractive tool for the detection of H2O2. Other electrochemical methods such as cyclic voltammetry, linear sweep voltammetry and differential pulse voltammetry are also used for the development of H2O2 biosensor. In the electrochemical methods, different types of modified electrodes have been used. Horseradish Peroxidase (HRP) enzyme is one of the mostly used materials for the modification of electrode. Different mediator such as ferrocene, hydroquinone, catechol, methylene blue, methylene green, nile blue, potassium hexacyanoferrate, thionine, toluidine blue etc. have been used with the enzyme modified electrodes. However, mediator-free HRP based biosensor was also reported. In this case, the direct electrochemistry of HRP enzyme plays vital role. Hemoglobin (Hb) protein is also used for the modification of electrodes. In most case, mediator is not necessary for protein modified electrodes. Enzyme free or protein free modified electrodes were also reported for the electrochemical method based H2O2 biosensor. Some other materials such as nanomaterials, conducting polymers, metal oxides, quantum dots, dendrimer, bilayer lipid membrane, kieselguhr membrane, ionic liquid, liquid crystal, etc. have been used with enzyme and protein modified electrodes. The sensitivity and selectivity of the H2O2 biosensor depends on how the electrodes are modified by different materials.