Real-Time Monitoring of Aptamer Functionalization and Detection of Ara H1 by Electrochemical Impedance Spectroscopy and Dissipation-Mode Quartz Crystal Microbalance

Peanut allergy, the most common cause of fatal-food-related anaphylaxis, is a lifelong disorder and the only existing therapy is avoidance of allergen-containing food. Detection of Ara h 1, the most important peanut allergen, is commonly performed by immunoassay techniques relying on the use of expensive and relatively unstable antibodies. Aptamers can overcome these drawbacks and offer a great potential for the development of reliable biosensors. Therefore, we will present a novel aptamer-based sensor for the label-free detection of Ara h 1. Amino (NH2)-terminated Ara h 1 aptamers were covalently attached to carboxylated gold surfaces employing carbodiimide chemistry. This functionalization procedure was followed in real time by electrochemical impedance spectroscopy and quartz crystal microbalance with dissipation monitoring. Subsequently, the functionalized surfaces were exposed to Ara h 1 solutions in TGK buffer. By combining the two techniques, we can measure in a wide concentration regime varying from the low nanomolar range (1-15 nM) via electrochemical impedance spectroscopy to the higher concentrations (25-250 nM) by microgravimetric detection. In summary, a fast, low-cost and sensitive sensor platform for Ara h 1 detection has been developed, which can be operated as a ‘stand-alone device’, making it well suited for applications such as the screening of trace allergens