Pollutant soot of diesel engine exhaust transformed to carbon dots for multicoloured imaging of E-coli and sensing cholesterol

A convenient method for the synthesis of water soluble, fluorescent carbon dots from environmental pollutant diesel soot is described. The soot, generated from the exhaust of diesel engines as black, diesel particulate matter (DPM), is an environmental pollutant. This pollutant has been utilized as the precursor carbon source to create water soluble versions of carbon dots by chemical oxidation. The small sized water soluble carbon dots once separated display multicoloured emissions covering the green to red and extended to the near-infrared region. These have been used in imaging Escherichia coli and further used in sensing cholesterol.