Method of functionalization of a gate electrode of a field-effect transistor sensor

A method of functionalization of a gate electrode comprising the steps of:

• forming a layer of biological recognition elements on a surface of said gate electrode, wherein said layer of biological recognition elements include a self- assembled structure of one or more specific-binding-pair-forming substances, the self- assembled structure including a biological self assembled structure of one or more specific-binding-pair-forming substances,
• treating the layer of biological recognition elements with a solution containing a blocking agent to fill vacancies and prevent nonspecific binding in the self-assembled structure, wherein said blocking agent is a Bovine Serum Albumine solution,
• wherein said one or more specific-binding-pair-forming substance immobilized in said layer of biological recognition elements are packed at a density between 0.1×104 μm−2 and 10×104 μm−2;
• wherein the layer of biological recognition elements includes a biological self- assembled structure (B SAM) including said one or more specific-binding-pair-forming substance and a chemical self-assembled structure (C SAM) whereon said biological self-assembled structure is grafted,
• wherein each of said chemical self-assembled structure (C SAM) and biological self-assembled structure (B SAM) is a self-assembled monolayer (SAM) structure,
• wherein the chemical self-assembled monolayer (C SAM) is added to the gate electrode by means of a precursor consisting of a layer of alkanethiols terminating with carboxylic functionalities,
• wherein said treating the layer of biological recognition elements (SAM) with a solution containing a blocking agent to fill vacancies and prevent nonspecific binding in the self-assembled structure (SAM) further comprises saturation of unreacted activated carboxy groups of said chemical self-assembled monolayer (C SAM) by means of concentrated solutions of amines for a time long enough to allow the reaction with all the activated carboxylic groups.