Research Highlights

Glowing sensor to detect heavy metal, image cancer cells

doi:10.1038/nindia.2018.110 Published online 28 August 2018

Researchers have synthesised light-emitting silicon quantum dots that can rapidly detect minute traces of chromium, a cancer-causing heavy metal, in water samples1. The quantum dots can also image human lung cancer cells, making them potentially useful as a sensor to diagnose lung cancer. 

Current methods for detecting heavy metals such as chromium are expensive and time-consuming. Besides, these methods require toxic compounds harmful to humans. 

An international research team including researchers from S. V. National Institute of Technology in Gujarat, India, converted a silicon-based organic compound into light-emitting silicon quantum dots using ascorbic acid. They then tested the efficiency these dots in detecting chromium in water samples and in imaging human lung cancer cells.

The light-emitting intensity of the dots decreased with increasing chromium concentration in water samples. This decrease happened within 30 seconds of exposure, showing that the sensor could detect chromium rapidly.

The sensor also selectively detected chromium even in the presence of other heavy metals that are usually found in contaminated water.

The dots, when cultured with human lung cancer cells, easily entered the cells. Instead of killing the cancer cells, they stayed inside the cells and made them emit green light. This indicates that the dots are non-toxic to the cancer cells.


1. Phan, L. M. T. et al. Synthesis of fluorescent silicon quantum dots for ultra-rapid and selective sensing of Cr (VI) ion and biomonitoring of cancer cells. Mater. Sci. Eng. C. 429 – 436 (2018)