Xanthine, which is an organic molecule found in most human body tissues and fluids, is a methabolic product on the pathway of purine degradation, and is converted to uric acid by the action of the xanthine oxidase enzyme.
Xanthinuria, also known as xanthine oxidase deficiency, is a rare genetic disorder that appears when there is an excess of xanthine in serum. This can lead to serious pathologies such as renal failure or gout. Therefore, fast and sensitive diagnosis methodologies for determining xanthine at very low concentrations are crucial.
In this work, published in Advanced Materials Interfaces, a group of ICMAB researchers lead by Dr. Núria Crivillers, have prepared a hybrid material, based on reduced graphene oxide modified with a stable organic radical, to exploit both the antioxidant activity of the reduced graphene oxide and the electrochemical reactivity of the organic radical towards superoxide anion radical (O2·-), which is derived from the xanthine/xanthine oxidase enzymatic system.
The novel electrochemical biosensor enables the detection of xanthine with a decreased detection limit 100 times with respect to previously reported sensors. Moreover, this graphene-based biosensor can overcome the limitations of the current methods, which are usually expensive, complicated and time consuming, thanks to its simplicity, rapidness, sensitivity, specificity and low cost.
Scheme and electron microscopy image of the graphene-based biosensor. The superoxide anion radical is formed when xanthine is converted to uric acid by the action of xanthine oxidase. Red color for carbon; green for chlorine.
Synergistic Exploitation of the Superoxide Scavenger Properties of Reduced Graphene Oxide and a Trityl Organic Radical for the Impedimetric Sensing of Xanthine. Gonca Seber, Jose Muñoz, Stefania Sandoval, Concepció Rovira, Gerard Tobias, Marta Mas-Torrent, Núria Crivillers. Advanced Materials Interfaces. 2017, 1701072, DOI: 10.1002/admi.201701072