Probe functionalization with a Rhop-3 antibody: toward a Rhop-3 antigen immunosensor for detection of malaria.

The antibody specific for the malaria protein, Rhop-3, and FL-Rhop-3, were immobilized on the surface of a gold electrode modified with cysteamine. Colloidal gold was used to enhance the detection signal for Rhop-3 antigens. The Rhop-3 antibody was also immobilized on gold electrodes preactivated with dithiobis(succinimidyl proprionate) (DSP). Immobilization was performed at room temperature and at 37 °C. Cyclic voltammetry (CV) was used to monitor the interaction between the immobilized antibody and its cognate antigen in solution, using ferricyanide, K3Fe(CN)6, as reporting electroactive probe. Tests indicate recognition of Rhop-3 protein by the immobilized antibody. Antigen recognition was enhanced by incubation at 37 °C compared with room-temperature incubation. Our results suggest that an immunosensor can be developed and optimized to aid detection of Rhop-3 antigens in samples from malaria patients. As far as we are aware, this is the first amperometric immunosensor targeting Rhop-3 antigen as a malaria biomarker.