Detection of biomarkers with carbon nanotube-based immunosensors

A facile and capable method of preparation of sensitive carbon nanotube (CNT)/polysulfone/RIgG immunosensor is discussed in this chapter. The immunosensor is based on the modification of disposable screen-printed electrodes by phase inversion method. CNT/polysulfone membrane acts as the reservoir of immunomolecules as well as a transducer. This configuration offers large surface area, elevated porosity, and mechanical flexibility. The comparison with graphite/polysulfone/RIgG immunosensors shows a significantly improved sensitivity for those prepared with CNTs coupled with polysulfone (PSf). The immunosensing scheme is based on the competitive assay between free and labeled anti-RIgG for the available binding sites of immobilized rabbit IgG (RIgG). The RIgG is incorporated into the PSf immunosensor using a phase inversion method. Horseradish peroxidase enzyme is used as label and hydroquinone as electrochemical mediator. The limit of detection for competitive assay is 1.66 microg/mL. The sensitivity is six times higher for MWCNT-based than for graphite-based electrodes.