DISSERTATION

_____________________________________________________________ Results and Discussion
used enzyme in amperometric biosensors. In the presence of glucose and a suitable redox
mediator it provides enhanced catalytic currents due to the continuous recycling of the redox
probe 107 . The modification of GOx is readily achieved by reductive amination of the
deglycosylated enzyme. Therefore, the acridine orange-glucose oxidase conjugate (AO-GOx)
was synthesized by binding the acridine orange moiety via a flexible 14-atom-long tether to
deglycosylated GOx via reductive amination using NaBH4 (Figure 3.51).
To assure that the enzyme remains active towards the oxidation of glucose even after the harsh
conditions employed during synthesis, electrochemical characterization of AO-GOx was
performed. CVs were recorded in PB containing ferrocene methanol as redox mediator and
glucose as substrate for GOx before and after addition of AO-GOx. The observed catalytic
current upon addition of the intercalating compound confirms that the enzyme remained intact
and that it can still transfer electrons to the electrode via the redox mediator (Figure 3.52).
Figure 3.52. Electrochemical characterization of the AO-GOx intercalating compound.
CVs recorded at a bare gold electrode in a solution of 10 mM PB, 450 mM K2SO4
containing 1 mM ferrocene methanol and 100 mM glucose without AO-GOx (grey line)
and with increasing concentrations of AO-GOx (black lines). Measurements were made
with a scan rate of 10 mV/s in a potential window of -0.1 to +0.45 V vs. Ag/AgCl/3 M KCl.
3.5 Intercalation as a DNA detection technique 98