1. SensorLab (UWC Sensor Laboratories), University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa
2. Nanotechnology Innovation Centre, Advanced Materials Division, Mintek, Private Bag X3015, Randburg, Johannesburg 2125, South Africa
3. Department of Biotechnology, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa
4. Department of Chemistry, University of Cape Town, Private Bag X3, Rondebosch, Cape Town 7701, South Africa