Labeless Immunosensor Assay for the Stroke Marker Protein S-100[β] Based Upon an AC Impedance Protocol

Abstract

We developed label less immunosensors for the stroke marker protein S-100[β], utilizing polyaniline electrode microarrays as substrates to immobilize biotinylated S-100[β] antibodies using classical affinity approaches. The AC impedance studies, before and after exposure to solutions of S-100[β], showed increasing antigen concentration caused increases in the real component of the impedance. Subtracting specific and non-specific antibody responses eliminated non-specific adsorption effects. Linear impedimetric responses toward S-100[β] in buffer solutions over a concentration range of 0–50 pg ml⁻¹ were observed. The limit of detection of the immunosensor was 1 pg ml⁻¹ S-100[β], discrimination was possible at 10 pg ml⁻¹.

This work, including funding for ACB, has been supported by the European Community QLRT-2001-02583 (SMILE) and NMP2-CT-2003-505485, (ELISHA) Framework VI contracts.