Sensors for the detection of hydrogen peroxide have come into the spotlight in recent decades due to the prevalent influence of the oxidative stress on numerous life processes including cell cycle, signaling pathways, defensive responses, unintended cell damage, etc. Non-invasive methods of H2O2 detection are important due to the implications of reactive oxygen species in the cell and DNA damage. The use of enzymatic biosensors has been the main way to detect hydrogen peroxide. However, the cost and difficulties in maintaining constant enzyme activity in enzyme-based sensory films has been a great disadvantage of these sensors. In this work, we have investigated novel sensors for hydrogen peroxide using catalyst-coated reduced-graphene oxide substrates. We have found that graphene oxide electrodes can be readily modified with Prussian Blue (PB) catalyst and reduced electrochemically to provide low ohmic-drop current-collection pathways. The presence of the reduced graphene oxide (rGO) has enabled achieving fast biosensor response to H2O2 (t95% = 5 s) and low limit of detection, LOD = 10-8 M. We have also examined the means for reducing interference due to the ascorbic acid, a common antioxidant. We have developed a copolymer able to block the ascorbic acid waves while still maintaining a good response of the sensor to hydrogen peroxide. Furthermore, the immobilization of an enzyme (horseradish peroxidase or laccase) has enabled us to determine concentrations of phenolic species in various antioxidant media. The composite sensors designed are promising candidates for inexpensive and scalable sensors for hydrogen peroxide and testing of enzyme activity in synthetic and biological samples.

Novel biosensors for determination of phenolic compounds using catalyst-loaded reduced graphene oxide substrates

248th National Meeting (2014)

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