Synergistic Exploitation of the Superoxide Scavenger Properties of Reduced Graphene Oxide and a Trityl Organic Radical for the Impedimetric Sensing of Xanthine

Abstract This work is based on synergetically exploiting the activity of graphene‐based materials and trityl free radicals to sense xanthine (X) by their combined scavenging properties for superoxide anion radical (O₂^•−). For this, reduced graphene oxide (rGO) and rGO covalently functionalized with a perchlorotriphenylmethyl (PTM) radical derivative (rGO@PTM) are synthesized, characterized, and casted on an electrode surface to achieve a highly sensitive electrochemical recognition platform for xanthine determination. The electrochemical analysis is based on impedimetrically monitoring a radical‐involved reaction on the graphene‐based electrode surface after reacting with such O₂^•− derived from the xanthine/xanthine oxidase enzymatic system. The presented strategy yields to determine X at nm levels, decreasing the detection limit 100 times with respect to previously reported (bio)sensors.