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Imagine a particle so small, yet so powerful that its use in diagnostic biosensors could lead to quicker and simpler detection of diseases and toxic substances. Dendrimers are ball-shaped nano-molecules of about 12 nm – 16 nm and Dr. Omotayo Arotiba’s research is all about how these small molecules are being used to improve diagnostic methods for cholera and HIV.

Based at the Department of Applied Chemistry at the University of Johannesburg, Dr. Arotiba is using dendrimers to assist development of biosensors for cholera and HIV, in collaboration with the CSIR. Biosensor research, as we will read more about in upcoming issues, in general aims to develop fast, accurate and low cost devices that can detect various substances, from the human body to food and the environment. A biosensor works a bit like a fisherman fishing with certain bait. In an HIV biosensor, short pieces of DNA called aptamers act as the “bait” to recognize a specific HIV protein. Upon contact with this HIV protein, the aptamer changes shape and this yields a positive test result.

Such sensing systems could, for example, enable HIV detection within the ‘window period,’ when viral load is very low. So where do the dendrimers come into play? The “bait” molecules in biosensors, such as proteins and aptamers, need a “comfortable” surface to function properly. Loss of function of biological molecules used in sensors is a common problem as the immobilization onto sensors can be denaturing. Dendrimers provide an environment that is “friendly” to DNA and proteins and Dr. Arotiba’s group has managed to successfully attach biomolecules to dendrimers.Owing to their nanoscale dimensions and reactive surface, dendrimers are also being used to vastly increase the surface area and sensitivity of detection platforms such as electrochemical sensors used, for example, in the detection of very low concentrations of heavy metals such as arsenic and lead in water.

Armed with dendrimers as a formidable nano-tool, this technology is a step closer to giving us quicker, simpler and more sensitive detection of diseases and toxic substances. These very small molecules may still have very big implications for South Africa and that indeed is the promise of nanotechnology.

Writer: Febe Wilken

Photo Credit: Febe Wilken