ELSEVIER Analytica Chimica Acta 338 (1997) 191-198 ANALYTICA CHIMICA ACTA Ferrocenyl silicon-based dendrimers as mediators in amperometric biosensors Josh Losadaa,*, Isabel Cuadradob, Mois& Morhb, Carmen M. Casado’, Beatriz Alonsob, Mario Barrancob “Drpurtamento de Ingenierh Q&mica Industrial, Escuela Tknica Superior de Ingenieros hdu.vtrirdr.\. Universidad PolitCcnica de Madrid, 28006h4adrid. Spuin hDepurtamento de Quimica InorgLinica, Facultad de Ciencias. Universidad Autrinoma de Modrid. Cuntobhco. 2804%Madrid. Spain Received 4 June 1996; revised 24 September 1996: accepted 26 September 1996 Abstract The application of ferrocene-containing dendrimers as mediators in amperometric biosensors is described. The steady-state amperometric response of carbon paste electrodes containing these dendritic relay systems and glucose oxidase is investigated as a function of the glucose concentration and the applied potential. The results show that these sensors respond rapidly to the addition of glucose. The dependence of the glucose sensor response on the size, the number of organometallic redox centers and the nature of the organosilicon dendritic framework is discussed. Keword.v: Riosensors; Amperometry; Dendrimers; Ferrocenes; Glucose 1. Introduction Dendrimers are a new class of well-defined functionalized macromolecules with a highly branched architecture, constructed by iterative reac- tion sequences. These new materials have attracted considerable attention in the past few years because of their large size, controllable peripheral function- ality and other valuable properties which make them promising for a variety of applications. [l-3]. The incorporation of organometallic moieties in dendritic structures [4] is a challenge of growing interest since it provides new opportunities to modify the unusual *Corresponding author. Fax: +34 1 336 3009. properties of dendrimers, as well as for tailoring a rich variety of nanostructured organometallic macro- molecules of desired nuclearity, possessing new topologies, and exhibiting attractive electrical, opti- cal, magnetic and catalytic properties. Remarkably, dendritic macromolecules containing a controlled number of redox-active organometallic centers (nu- clearity) are good candidates to play a key role in a number of applications such as in multi-electron redox catalysis. in photoinduced electron-transfers. as molecular electronic devices, and others. We recently synthesized a new class of ferrocenyl silicon dendrimers [5] and we have demonstrated the feasibility of modifying electrode surfaces with these redox-active organometallic dendritic macromole- cules [6]. 0003.2670/97/$17.00 Copyright #Q 1997 Elsevier Science B.V. All rights reserved. PII SOOO3-2670(96)00462-X