Single-step scalable conversion of waste natural oils to carbon nanowhiskers and their interaction with mammalian cells

Waste cooking oil has daily deliberate hazardous effects on human health due to consumption of re-cooked oil and on the environment from disposal of the waste oil. These hazards can be controlled if there are ways to economically convert the waste oils into industrially relevant materials. Large-scale controlled catalytic conversion of the waste natural oils to carbon nanowhiskers (CNWs; diameter: 98-191 nm, length: <= 2 mu m) was achieved by a one-pot, environmentally friendly process. The no-cost CNWs consist of carbon spirals with spacing between two adjacent layers at 3.1 +/- 0.2 nm and arranged perpendicular to the whisker axis. The reactions were performed inside a sealed container at 500-850 degrees C and autogenic pressure for 4-10 h. It was demonstrated that the gaseous pressure from the decomposition of the fatty acids was crucial for formation of the semi-graphitic filamentous structures. The dilute acid-washed catalyst free CNWs were found to be negligibly toxic to the mammalian cells and can be localized inside the cell nucleus. The cellular internalization studies of the fluorescent CNWs demonstrated their viability as potential delivery vehicles into the mammalian cells.