Development of Low Molecular Weight Ferrocene–Biotin Bioconjugates as Electrochemical Sensors

A library of ferrocene–biotin bioconjugates has been produced using solid phase methods and evaluated for a change in redox activity in the presence of avidin. This was carried out as a means to explore the potential of low molecular weight ferrocene containing molecules to undergo redox changes due to interactions with larger, biological systems. The affinity and stability of the avidin–biotin interaction provides a platform to demonstrate that substrate binding produces an electrochemical change. The work presented focuses on the solid-phase synthesis and characterization of ferrocene (Fc) substituted with various biotin derivatives as model systems to be used in electrochemical studies. The biotin moiety was coupled to avidin and characterized using electrochemistry and fluorescence spectroscopy. Competition and modeling studies showed that the bioconjugate is selective for avidin and responsive at concentrations in the low nanomolar level using square wave voltammetry.