Methods of immobilisation of biomolecules on a silicon based transducer

Feasibility of a capacitive biosensor, consisting on an antibody layer fixed onto the top oxide layer of an heterostructure EIS (electrolyte- insulator-semiconductor), has been studied onto silicon substrates. For such a biosensor the sensitive layer containing the active species must act as an electrically blocking capacitor. Antibodies (anti-afoetoprotein) have been grafted onto silica through three different spacing reagents: aminosilanes, diols, heteropolysiloxane membranes. The more interesting results have been obtained with polysiloxane membranes but these last not allow direct detection of the antibody- antigen interaction.