Novel cancer treatment using drug release controlled by
27 September 2012
Controlled drug release at the site of a tumour using
near-infrared stimulation of nanoparticles shows promise as a
non-invasive treatment for deep cancer.
The research, by the Department of Bioengineering at the National
University of Singapore (NUS) has been published online in Nature
Medicine. This is a world first for the use of nanoparticles for
non-invasive photodynamic therapy of deep cancer.
How does their technology work?
The team has discovered a way to control gene expression by using
nanoparticles that are able to convert near-infrared (NIR) light to
visible or UV light, which in turn causes a drug to be released.
These nanoparticles can be introduced into target sites of the
patient, where they can be activated.
Schematic showing the process of NIR activating
Genes release certain proteins in our body to ensure that our
internal “machinery” works well and we remain healthy. However,
sometimes, the process can go awry and cause our body to
malfunction, leading to various disease. But doctors can put this
right by manipulating the process of gene expression by using UV
light. However, UV light may cause more harm than good.
Assoc Prof Zhang, the team leader, said: “NIR, besides being
non-toxic, is also able to penetrate deeper into our tissues. When
NIR reaches the desired places in the body of the patient, the
nanoparticles which we have invented, are able to convert the NIR
back to UV light (up-conversion) to effectively activate the genes
in the way desired — by controlling the amount of proteins expressed
each time, when this should take place, as well as how long it
should take place.”
Their findings from this study were earlier published in
Proceedings of the National Academy of Sciences, USA in May
As the up-conversion nanoparticles can also be used to produce
visible light, the team has extended its application to other
light-based therapies. Conventional light therapy for treating
tumours uses visible light to activate light sensitive drugs that
can kill cancer cells. However, such visible light is not
penetrative enough to reach deep-seated tumours. The team’s method
of employing NIR is able to penetrate much deeper. The team’s
findings have been published online in Nature Medicine.
Their novel use of nanoparticles made news in 2010. Coated with
mesoporous silica, these particles are each tasked to conduct
“up-conversion”. Their paper “Multicolour Core Shell-Structured
Up-conversion Fluorescent Nanoparticles” was published in Advanced
Materials in December 2008. It was one of the most highly-cited
papers because of its relevance in today’s science.
Wide range of applications
“By using our nanoparticles, drugs can be activated by NIR light
which is safe. The light is also able to penetrate deeper into
tissues to treat diseased cells," said Assoc Prof Zhang.
Co-author of the paper, PhD student Mr Muthu Kumara
Gnananasammandhan added that what they have developed is a platform
technology which can be customised for a wide range of applications.
For example, in addition to photodynamic therapy, their innovation
can also be used for bioimaging where the nanoparticles can be
attached to biomarkers, which will then attach to cancer cells,
allowing for better imaging of tumours and cancerous cells.
The six-member team comprises researchers from the faculties of
Engineering and Science, as well as the NUS Yong Loo Lin School of
The team is currently in collaboration with researchers at the
National Cancer Centre Singapore to pursue a project funded by the
Agency for Science, Technology and Research (A*STAR) that will
assess the safety and efficacy of the technology to pave the way for
pilot clinical trials in the future.
The team has also embarked on several other projects that make
use of the up-conversion nanoparticle for point-of-care diagnostics
for diseases. They have received the proof-of-concept (POC) grants
from the Biomedical Engineering Programme (BEP) which is funded by
the Science and Engineering Research Council (SERC) at A*STAR and
the National Research Foundation, to develop these point-of-care
diagnostic kits for rapid detection of bacteria and biomarkers.