Nanosized flower-like ZnO synthesized by a simple hydrothermal method and applied as matrix for horseradish peroxidase immobilization for electro-biosensing

Nanosized flower-like ZnO was synthesized by a simple hydrothermal method which is a convenient, environment friendly, inexpensive and efficient process. Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to confirm the material structure and the crystallite microstructure. Then ZnO was dispersed in the chitosan solution to form a ZnO/chitosan composite matrix for the fabrication of H2O2 biosensor. This composite combined the advantages of inorganic species (ZnO) and organic polymer (chitosan). The parameters affecting the fabrication and experimental conditions of biosensors were optimized. Using hydroquinone as the mediator, the biosensor showed a fast response of less than 5 s with the linear range of 1.0 × 10−5 to 1.8 × 10−3 M H2O2 with a correlation coefficient of 0.995 (n = 20). The detection limit of the sensor was found to be 2.0 μM, based on a signal-to-noise ratio of 3. The biosensor exhibited satisfactory reproducibility and stability and retained about 78% of its original response after 40 days storage in a phosphate buffer at 4 °C.