Biophysics of Electrochemical Cell Lysis of Malaria Parasite

Abstract

The cell lysis is an essential part of sample preparation because the target gene or protein encapsulated by cellular membrane can only be available in the extracellular space for any type of assay to work. Yet, a simple method that is compatible with downstream assay such as enzyme-linked immunosorbent assay (ELISA) or polymerase chain reaction (PCR) has been introduced. Here, we report an electrode-based cell lysis method for nucleic acid extraction. A pair of electrode was used in the microfluidic device to electrochemically generate hydroxyl ions which permeabilize and break the lipid bilayer. The key advantages of electrochemical lysis are that (1) hydroxyl ions are compensated with hydrogen ions generated from the paired electrochemical and thus does not interfere with downstream assays, and (2) the simplicity of the system integration on-chip by electrode fabrication. The on-chip cell lysis module was used to lyse human blood infected with malaria parasites. At 3 V applied potential, the complete lysis of all the red blood cells (RBC), including malaria-infected RBC and non-infected RBC, occurred within 200 seconds, but intact malaria parasites were already absent after 30 seconds of lysis. The rapid lysis of malaria may be explained by the weakened lipid bilayer of RBCs when it is infected with malaria parasites, and thus malaria-infected RBCs may become more susceptible to electrochemical lysis than non-infected RBCs. The selectivity of malaria lysis over average RBCs was the highest at 3 V with a factor near 120. This can potentially used toward our advantage to isolate the malaria sample from most non-infected RBCS. After lysing the malaria-infected RBC rapidly and switching off the lysis, the remaining intact-RBC can be separated from the malaria sample to reduce the PCR inhibition due to the RBC-released hemoglobin.