Hsp90-functionalized polypyrrole nanotube FET sensor for anti-cancer agent detection

A rapid and efficient strategy to detect novel heat shock protein 90 (Hsp90) inhibitors as anti-cancer agents was developed with field-effect transistor (FET) sensor based on carboxylated polypyrrole nanotubes (CPNTs). First of all, the CPNTs were successfully fabricated by using cylindrical micelle templates in a water-in-oil emulsion system, and the functional carboxyl groups were effectively incorporated into the polymer backbone during the polymerization by using pyrrole-3-carboxylic acid (P3CA) as a co-monomer. A liquid-ion gated FET-type sensor was readily constructed on the basis of CPNTs as the conductive channel. The CPNTs were covalently immobilized onto the microelectrode substrate to maintain stable electrical contact between the CPNTs and the microelectrodes in the liquid phase. Subsequently, Hsp90 was attached to the CPNTs surface through condensation reactions between the terminal amino groups in Hsp90 amino acid residues and the carboxyl groups on the CPNTs. The Hsp90-conjugated CPNT FET sensor provided a convenient and sensitive method to observe the affinity between Hsp90 to Hsp90 inhibitors in real-time. This result suggests that the FET sensor will open up the potential application for new anti-cancer drug discovery (Hsp90 inhibitors) after a judicious optimization.