Building a sensitive immunosensing platform based on oriented immobilization of histidine-tagged antibody on NiO-decorated SWNTs

Today tuberculosis (TB) remains one of the biggest health problems with high rates of morbidity and mortality in the world. An antigen, CFP-10, which found in tissue fluids of tuberculosis patients can be used as the marker protein for early and simplified diagnosis of TB. A sensitive format for immunosorbent assays has been developed to meet the increasing levels of performance demanded in the medical, veterinary, and bioterrorism prevention arenas. This paper introduces the concept of a NiO-decorated SWNTs substrate as a facile means to capture histagged antibody orientedly and increase its surface capacity and thereby improve the detection limit. To this end, histagged anti-CFP-10 was immobilized on a NiO-decorated SWNTs modified substrate via chelation between NiO and histidine-tags. An immuno assay is carried out that couples the specificity of antibody–antigen interactions with the high sensitivity based on surface plasmon resonance detection. The effect of NiO-SWNTs on the orientation of antibody was investigated through comparing with the SWNTs. Implementation of NiO-SWNTs resulted in 22-fold enlargement of the SPR signal at the limit of detection.