Peptide-modified electrolyte-gated organic field effect transistor. Application to Cu²⁺ detection

This work proposes an approach for Cu²⁺ sensing in water which combines the selectivity of the Gly-Gly-His (GGH) peptide probe with the sensitivity of the electrolyte-gated organic field-effect transistor (EGOFET). The oligopeptide probe was immobilized onto the gate electrode of the transistor by electrooxidation of the primary amine of the glycine moiety. Cu²⁺ complexation by the grafted GGH was at first electrochemically evidenced, using cyclic and square wave voltammetries, then it was demonstrated that GGH-functionalized EGOFETs can transduce Cu²⁺ complexation through a significant threshold voltage shift and therefore a change in drain current. The limit of detection is ca. 10^-12 M and the sensitivity in the linear range (10^-12 - 10^-8 M) is 1 mA dec^-1 (drain current variations).