Silica gels as electrode membranes in the hydrogen peroxide potentiometric biosensor

Hydrogen peroxide determination in trace concentrations has grown in different scientific areas A H 2 O 2 biosensor based on silica gel membrane (SGM) obtained by the sol-gel method without mediators has not been yet reported. In this work, a SGM for covering a Pt electrode was used in order to design a H 2 O 2 biosensor. The potentiometric response of the reference electroactive species such as [Fe(CN) 6 ] 3- and [Fe(CN) 6 ] 4- encapsulated and non-encapsulated within the SGM shown a Nernstian behavior. This means that the prepared SGM had a acceptable ionic conductivity to be used as selective H 2 O 2 biosensor. This was constructed by the immobilization of catalase inside the SGM. The potentiometric determinations of H 2 O 2 done with this biosensor showed a linear range starting in 6.66 x 10 -7 M up to 2.66 x 10 -6 M. This range was similar to that previously reported for the amperometric determinations. Finally, it is worth to mention that this potentiometric biosensor is cheaper, simple and not amperometric measurements must be achieved in the following steps.