Enzymatic Biosensors towards a Multiplexed Electronic Detection System for Early Cancer Diagnostics

Enzymatic biosensors are expected to play a key-role in bio techno logical and biochemical analysis as shown by the success of glucose sensors in diabetes treatment. The aim of this work is to develop a multiplexed electronic detection system for early cancer diagnostics. Therefore, various enzymes were adsorbed to differently modified surfaces. Electrochemical optical waveguide lightmode spectroscopy (EC-OWLS) and electrochemical quartz crystal microbalance with dissipation (EC-QCM-D) were used to measure the mass and the activity of the adsorbed enzymes. The enzymes were specifically immobilized on a protein resistant PLL-g-PEG surface in order to reduce the loss of activity due to denaturation. In addition, enzymes were also incorporated into DNA-tagged vesicles to increase the signal and therefore the sensor sensitivity. The enzymatic activity of the different systems was compared. To further increase the sensitivity, ferrocyanide was used as an electron mediator.