A Novel Ferrocene-Encapsulated Palladium-Linked Ormosil-Based Electrocatalytic Biosensor. The Role of the Reactive Functional Group

A novel palladium-linked ormosil material with encapsulated ferrocene is reported along with its application in bioelectrocatalysis. The Pd-glycidoxypropyltrimethoxysilane is made by mixing an aqueous solution of palladium chloride and glycidoxypropyltrimethoxysilane. The linkage of palladium with glycidoxypropyltrimethoxysilane is confirmed by UV-vis, mass, and 13C spectroscopy. It is suggested that Pd is sandwiched between two molecules of glycidoxypropyltrimethoxysilane replacing oxygen. The new ormosil is made using Pd-linked silane precursor containing ferrocene monocarboxylic acid, trimethoxysilane and HCl. The formation of ormosil at two different temperatures (10 and 30 °C) is also studied, with the result that the ormosil formed at 10 °C does not show electrocatalysis of glucose oxidase whereas the ormosil made at 30 °C is found to be an efficient bioelectrocatalyst. The cyclic voltammetry results show peak separation of 57–59 mV of encapsulated ferrocene made at 30 °C and relatively large peak separation of the one made at 10 °C. The performance, stability, and reproducibility of the new ormosil based glucose biosensor are discussed. Another important investigation in support of the above outcome is reported showing the self-assembly of palladium on the reactive solid state ormosil surface. The reactive ormosil is developed using a mixture of trimethoxysilane and 2-(3,4-epoxycyclohexyl) ethyltrimethoxysilane in acidic medium.