Determination of membrane shear elastic modulus by micropipette aspiration.

Bright-field digitally captured images of a typical micropipette (1.3 μm internal diameter) used for determination of the shear elastic modulus of (A) an uninfected RBC and (B) an RBC infected with a mature malaria (P falciparum) parasite as described in “Materials and methods.” A portion of the RBC membrane aspirated into the pipette can be visualized clearly, shown here at a pressure of 2.0 mm H₂O (A) and 4.0 mm H₂O (B). Note that in panel B, only PRBCs that remained approximately discoid and that contained relatively small but mature trophozoites were measured so that there was sufficient free membrane to aspirate away from the parasite itself. Scale bar, 5 μm.