Tin oxide nanorod array-based electrochemical hydrogen peroxide biosensor

Abstract

SnO2 nanorod array grown directly on alloy substrate has been employed as the working electrode of H2O2 biosensor. Single-crystalline SnO2 nanorods provide not only low isoelectric point and enough void spaces for facile horseradish peroxidase (HRP) immobilization but also numerous conductive channels for electron transport to and from current collector; thus, leading to direct electrochemistry of HRP. The nanorod array-based biosensor demonstrates high H2O2 sensing performance in terms of excellent sensitivity (379 μA mM-1 cm-2), low detection limit (0.2 μM) and high selectivity with the apparent Michaelis-Menten constant estimated to be as small as 33.9 μM. Our work further demonstrates the advantages of ordered array architecture in electrochemical device application and sheds light on the construction of other high-performance enzymatic biosensors.

Keywords: Biosensor; Nanorod array; Nanostructure; SnO2.

Figure 1

a Typical SEM image of SnO₂ nanorod array. b HRTEM image of an individual nanorod. c XRD and d Raman spectrum of the SnO₂ nanorod array

Figure 2

CVs of HRP/SnO₂ nanorod array electrode in N₂-saturated PBS solution at different scan rates

Figure 3

a CVs of HRP/SnO₂ nanorod array electrode in N₂-saturated PBS solution containing 0, 0.8 and 4 μM H₂O₂, respectively. b Effect of HRP dosage on the reduction current responses of the developed enzymatic electrode. Scan rate: 500 mV s⁻¹

Figure 4

Calibration curve for the SnO₂ array-based H₂O₂ biosensor at −0.47 V. Inset is the corresponding Lineweaver–Burk plot