Synthesis and characterization of carbon nanotubes on clay minerals and its application to a hydrogen peroxide biosensor

In this study, we demonstrate the synthesis of carbon nanotubes (CNTs) on clay minerals, and the development of biosensors based on Nafion-CNT/Clay-Au and Nafion-CNT/Clay-Au-Glucose oxidase (GOD) composite films for the detection of hydrogen peroxide (H2O2) and glucose, respectively. The CNTs are synthesized on nickel cation exchanged clay mineral platelets. From field-emission scanning electron microscope images, X-ray diffraction, Fourier transfer infrared and thermogravimetric analysis results, the clay layers are exfoliated and delaminated after the growth of CNTs on them. The mixed hybrid film of Nafion, CNT/Clay, Au particles and GOD is coated on the glassy carbon (GC) electrode to detect H2O2 or glucose. This film exhibits a detection limit of 5.0 x 10-5 M for H2O2 with a sensitivity of 280 nA mM-1. In addition, the amperometric response for glucose containing 2.0 mg mL-1 GOD in the Nafion-CNT/Clay-Au-GOD modified GC electrode exhibits a sensitivity of 620 nA mM-1 with a linear range up to 1850 μM. A higher sensitivity and shorter response time are observed with increasing GOD content in the composite matrix film. Besides, the highest sensitivity of 2032 nA mM-1 is obtained with the addition of the 10.0 mg mL-1 GOD in the composite film. Consequently, the CNT/Clay/Nafion medium can probably be a useful electrode for the development of sensors due to its high sensitivity and applicability