Direct detection of malaria infected red blood cells by surface enhanced Raman spectroscopy.

Surface enhanced Raman spectra (SERS) of normal red blood cells (RBCs) and Plasmodium falciparum infected RBCs (iRBCs) at different post invasion time were obtained based on silver nanorod array substrates. Distinct spectral differences were observed due to the cell membrane modification of RBCs during malaria infection. The SERS spectra of ring stage iRBCs had a characteristic Raman peak at Δv=1599cm(-1) as compared to those of normal RBCs, while the trophozoite and schizoid stages had identical SERS spectra with a characteristic peak at Δv=723cm(-1), which is significantly different from ring stage iRBCs, consistent with ongoing modification of the iRBC membrane. Since ring stage iRBCs of P. falciparum are found circulating in blood, such a difference provides a new strategy for rapid malaria detection. The limit of detection as well as the ability to detect a mixed iRBC and RBC solution was also investigated.