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Novel biosensor for early detection of cancer
Author: Liesel Koch
Published: 27/07/2018

​​​Too many cooks spoil the broth? No! It is a matter of two heads are better than one. At the Faculty of Engineering (Stellenbosch University) the smart approach to research these days is for different disciplines to work together to complement each other and to increase the impact of the research.

A perfect example of such an interdisciplinary project is the work done by Prof Willie Perold, an electronic engineer in the Department of Electrical and Electronic Engineering, and Prof Resia Pretorius (Department of Physiological Sciences in the Faculty of Science) who is an expert on blood cell morphology. Together they are working on a novel hand-held nano-electronic biosensor that will use only one drop of blood to diagnose cancer more rapidly and at a lower cost than current methods.

"We have been working together for some time and are co-supervising three postgraduate students," says Prof Perold. "Currently, we are working on the early detection of inflammatory conditions, such as cancer. Two of our projects investigate the occurrence of the protein serum amyloid A (SAA). This protein is interesting as it increases noticeably when there is inflammation in the body."

Prof Pretorius confirms this: "In full-blown stage 3 cancer, SAA levels are 1 000 times higher than normal. A great increase in serum amyloid A in the blood therefore is a sign that something is wrong."

Prof Perold adds: "With our biosensor we aim to pick up the onset of inflammation during the early stages by the detection of SAA in the blood sample. Long before cancer manifests, it should therefore be traceable through the high levels of SAA that 'gives it away'." 

In order to develop the small biosensor, Prof Perold builds on a previous project in which a similar device was developed to detect Escherichia coli in a few minutes. 

"The process to develop the small electronic device is simple," he explains. "We use a specific material, such as paper or an electrospun nanofibre, on which we attach a bio-recognition element, such as SAA antibodies. The fibre is then connected to an electronic circuit that measures resistance. The antibodies will only bind with the protein (SAA) that we want to pick up. Consequently, if a drop of blood is added to the sensor and SAA is present in the blood, binding will take place between the antibodies and SAA. This binding will result in a change in the electronic circuit, which indicates the presence of inflammation.

"The SAA antibodies we need for the biosensor are produced especially for us by a small South African spin-off company that manufactures artificially produced antibodies in Alpacas. Our hand-held nano-electronic biosensor has been patented and we are now looking for funding," Prof Perold concludes.

This sensor has many advantages over conventional methods of detecting inflammation. It is faster than conventional methods where blood samples have to be sent to a laboratory for analysis. Another advantage is the biosensor's size. Because it is small, it is portable and ideal for use as a point-of-care device in remote areas.

Prof Pretorius and Prof Perold did an 8-minute interview on Carte Blanche on 2018.05.04. See their interview on Medical Innovations with Claire Mawisa here.

Photo collage:

Left: An enlarged photograph of the printed biosensor.

Middle: Prof Wille Perold and Daniël Retief (postgraduate student) alongside the adapted inkjet printer that is used to manufacture biosensors in the nano-lab. The printer uses nanoparticle- and polymer ink mixtures to print conductive structures onto paper and other substrates. Mr Retief has a printed biosensor in his hand.

Right: Prof Resia Pretorius.