Biomedical probe created from spoiled oranges

A University of Sydney Ph.D. researcher is developing a cancer and serious disease-detecting biomedical probe that can be made from the juice of rancid oranges.

Called a nanobiosensor – a tiny probe that uses fluorescence to signal cells' pH in terms of their acidity or alkalinity – it detects whether cells are at risk, or in the early stages of cancer or other serious diseases. When human cells become more acidic, it can suggest that cancer is not far off.

The nanobiosensor, which measures only one-billionth of a meter, is made of fluorescent carbon dots that can be created from food waste, in this case, the juice of rotten oranges. The 'off' oranges were used for their high levels of ascorbic acid – which improves the nanobiosensor's functionality – and to minimize food waste going to landfill.

The process, published in the Chemical Engineering Journal, involves taking a tissue biopsy of cells suspected to be cancerous, which are put in a petri dish. Using a laboratory pipette (a scientific dropper) the nanobiosensor is then applied to the cells, which are then examined under a fluorescence microscope – a type of microscope that shows subtle light variations.

"Dramatic fluctuations in the acidity of cells can lead to inappropriate cell function, growth and division, and can lead to serious diseases " said lead researcher and Biomedical Engineering Ph.D. student Mr Pooria Lesani.