Label-Free Plasmonic Immunosensing for Plasmodium in a Whole Blood Lysate

In this paper, we report an experimental demonstration of malaria pathogen detection in a whole blood lysate using plasmonic nanostructures. The plasmon sensor utilizes extraordinary optical transmission through a nanostructure to directly probe antibody-antigen interactions. The measured refractive index sensitivity of the nanostructured sensor is 378 nm per refractive index unit in the visible range. The surface chemistry reported here provides highly site directed and stable antibody immobilization. To validate the observed response of the optical sensor, positive and negative control tests were performed. Results confirm that a refractive index change induced by the interaction between immobilized antibodies and malaria parasites is successfully detected by the fabricated sensor. The demonstrated plasmonic sensor is a compact, highly sensitive, cost effective, selective diagnostic tool for many portable biosensing applications, such as point-of-care diagnostics.