Typical transmission electron microscopy (TEM) images of Carbon dots. © IOP / STAM

Written by: Ian Fyfe

Carbon dots (C-dots) are light-emitting (luminescent) nanoparticles
that can be used to track biological processes inside cells. They
are less toxic than similar alternatives, making them more suitable
for use in live biological systems, but the light-emitting
properties of those currently made are not ideal.

A variety of approaches have been used to make C-dots, but most
require coating of the particles with other molecules to achieve
useful luminescence. Now, work led by Amita Pathak at the Indian
Institute of Technology has produced water-soluble C-dots that
selectively emit light across the entire visible range without any
surface coating.

The researchers produced these C-dots by breaking down the
carbohydrate dextrin with microwaves. The resulting C-dots emitted
different colours of light when excited by specific wavelengths,
even without coating them. Exactly how this multi-coloured
luminescence arises is unclear, but it allows precise control of
the light emission that can be tailored to specific needs.

To ensure that the C-dots were not toxic, the team added different
concentrations of the nanoparticles to cultured cells. After three
days, they determined how many cells had survived. Increasing
concentrations of C-dots made little difference to cell survival,
showing that the C-dots are not toxic and could therefore be used
in live tissue.

The properties of these new C-dots make them ideal for a variety of
bioimaging applications and for medical diagnostics. The same
researchers have already begun to look at how they may be used to
investigate interactions between drugs and cells.

References:

Nagaprasad Puvvada, B N Prashanth Kumar, Suraj Konar, Himani
Kalita, Mahitosh Mandal and Amita Pathak (2012) “Synthesis of
biocompatible multicolor luminescent carbon dots for bioimaging
applications” Sci. Technol. Adv. Mater. Vol. 13 p.
045008

DOI: http://dx.doi.org/10.1088/1468-6996/13/4/045008

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