Indirect Detection of Acrylamide Using a Novel Biosensor Element ^†

Acrylamide (AA), C₃H₅NO, is used worldwide in the synthesis of polymers and gels for wastewater treatments and in the paper industry. Naturally, it is formed in heat-treated food, mostly during the frying and baking of potatoes, cereals, and coffee beans. Its presence in food is dangerous as it is a neurotoxic and genotoxic compound. Triggered by new EU regulations, there is a high demand for reliable and cost-effective sensors in food and home appliances. In view of this, electrochemical sensors show high potential for the detection of toxic compounds. In the present work, we show the development of electrochemical biosensor elements, since AA is a non-active molecule and direct electrochemical detection is not possible. The sensors’ receptor element is based on modified commercial screen-printed electrodes (SPEs) that offer on-site and cost-efficient sensing. As an electrochemical transducer, conductive polyaniline (PANI) decorated with Au NPs was applied, enabling high sensitivity and limit of detection below the 10⁻⁶ M range. As a biological component, enzyme amidase was selected, since it is known that it catalyzes the hydrolysis of acrylamide into carboxyl acid and ammonia. The ammonia was finally detected using chronoamperometry. The chemical interaction between PANI and ammonia is well-known and thus was used as a base for the fabrication of an amperometric sensory platform for its aqueous detection at neutral pH. To understand AA and amidase interaction and decomposition into ammonia, PANI electrochemical synthesis and redox behavior in acidic and neutral media were used to study the mechanism of AA indirect detection.