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Graphene sensor detects malaria infection

09 February 2012



The NUS-designed graphene transistor can detect malaria-infected red blood cells

A cross-disciplinary team at NUS - comprising Prof Loh Kian Ping (Department of Chemistry and Graphene Research Centre), Ms Ang Kailian Priscilla (NUS Graduate School for Integrative Sciences and Engineering), Prof Lim Chwee Teck (Departments of Bioengineering and Mechanical Engineering), and his former research fellow, Dr Li Ang - has conceptualised and built a device for malaria detection using graphene transistor in a microfluidic channel. The team's paper, "Flow Sensing of Single Cell by Graphene Transistor in a Microfluidic Channel", was published in Nano Letters.

Most disease detection and diagnostic tools rely on microscopy and antibody staining. These require specialised training and are subject to misdiagnosis arising from human errors. Furthermore, cellular behaviours in a large population of cells make such measurements insensitive to changes occurring in individual cells.

Thus, the researchers decided to take a new approach to disease detection and diagnosis by looking for a change in cell surface charge at the single cell level. They selected graphene, an atomically thin two-dimensional carbon nanomaterial. Its unique properties such as visual transparency, ability to interface with living cells, electrical stability and sensitivity, make it ideal as a sensor.

The members designed a graphene device, which can be potentially used to study any kind of diseased cell, and apply it for malaria detection. Malaria-infected red blood cells export parasite-produced proteins to the membrane surface, and the resultant membrane 'knobs' are positively charged. Graphene, being extremely sensitive, is able to electrically detect these membrane knobs and differentiate the malaria-infected red blood cells from healthy ones.

The ability to do a statistical percentage count of the infected cells, as the blood cells flow through the graphene transistors in a microfluidic channel, shows great promise for clinical diagnostic applications.

The investigators are exploring integrating the graphene transistors in a lab-on-a-chip device which can perform high-throughput flow sensing of infected cells, with automated electrical readout for disease detection and diagnosis.


Schematic illustration of an array of graphene transistors in a microfluidic channel through which cells flow. Specific binding between proteins on positively charged knobs of infected red blood cells and receptors coated on graphene induces a distinct conductance change. Conductance returns to baseline value when infected cell exits the graphene channel.

Image: Priscilla Ang




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