A novel three-dimensional biosensor based on aluminum oxide: application for early-stage detection of human...

Immunosensors based on electrolyte-oxide-semiconductors (EOS) have been extensively researched over the last few decades. By electrochemical impedance spectroscopy (EIS) the specific molecular biorecognition of the antibody-antigen (Ab-Ag) can be detected providing an alternative quantitative system to immunoassay techniques. The electrochemical variations from a fabricated immunosensor can provide quantitative values for the analyte of interest at reduced costs and analysis time. In this context, a novel EOS substrate based on aluminum oxide (Al2O3) grown by atomic layer deposition on silicon was applied. The interaction between recombinant human (rh) interleukin-10 (IL-10) with the corresponding monoclonal antibody (mAb) for early cytokine detection of an anti-inflammatory response due to left ventricular assisted device implantation was studied. For this purpose, a 3D biosensor was composed of multi-walled carbon nanotubes with carboxylic acid functionalities (multi-walled carbon nanotubes-COOH) to increase the surface area for the range of human IL-10 detection. These were activated with N-hydroxysuccinimide and N-(3-dimethylaminopropyl)-N'-ethyl-carbodiimide hydrochloride for the immobilization of the anti-human IL-10 mAb. First, the interaction between the Ab and Ag was observed by fluorescence patterning to ensure that the biorecognition event was achievable. Then, EIS is explained for the quantification of commercial human IL-10 on this capacitance-based EOS macroimmuno-FET sensor.