At a technical breakfast, Romain Quidant presented his research into the
detection and treatment of cancer using gold nanoparticles illuminated with
laser light. Quidant, who was recently awarded the Fresnel Prize 2009 that recognizes
the highest level of excellence amongst emerging researchers in the field of
photonics, is an ICREA researcher at the UPC's
Institute of Photonic Sciences (ICFO) and a fellow of the Cellex Foundation
The interaction between light and gold nanostructures is not only useful for the treatment of cancer but also for its diagnosis.
“Drops” of gold that burn tumors
Quidant is among the leading researchers of a strategy called “plasmonic
oncology” that will revolutionize cancer treatment. He is working on this
groundbreaking research program thanks to the support of the Cellex Foundation
Barcelona. The idea is to introduce gold nanoparticles into tumor cells, to
which laser light would subsequently be applied. Thanks to the phenomena discovered
by this French researcher, the nanoparticles would heat up to such a degree
that the damaged cells would be completely burnt.
Nanoparticles are metal structures that measure just one millionth of a meter:
they have a diameter ten thousand times smaller than that of a hair. What is
revolutionary about this novel use of nanoparticles is that they can be designed
in such a way that they can be selectively introduced into a patient's
body so that they only penetrate damaged cells. Thus, the treatment would only
affect tumor tissues without damaging healthy ones, as happens with chemotherapy
The system is based on the twofold outcome of the nanoparticle engineering
carried out by the researchers. Firstly, the nanoparticles must be able to recognize
damaged cells and, secondly, they must become excellent nanosources of heat.
The former is achieved by coating the nanoparticles with molecules that detect
and go into the cancer cells. In the latter case, minute metal structures are
designed so that their shape optimizes the generation of heat in response to
an external light source.
The project is still at the experimental stage and is being undertaken in collaboration
with experts in medicine and biology. One of the key processes in the experimental
work is the selection of the particles from the damaged cells, which are inserted
once their possible toxicity has been minimized. In principle, gold is biocompatible
and is readily evacuated by body fluids, but the researchers must make sure
that the chemistry involved in the process does not affect the cells.
A nanolaboratory in a drop of blood
The interaction between light and gold nanostructures is not only useful for
the treatment of cancer but also for its diagnosis. Romain Quidant is working
on a chip that is made up of a multitude of metal nanostructures that are able
to send a light signal when they come into contact with cancer markers. This
“nanolaboratory” performs a vast number of analyses in parallel
from a single drop of blood. Each metal nanostructure is coated in molecules
(receptors) that are able to recognize and trap a specific cancer marker. When
this happens, the nanostructure responds to the external light differently to
when no markers are trapped.
The team led by Romain Quidant in this research line has already developed
a nanosensor prototype designed to detect doping substances in the blood, such
as the steroids that some sportspeople use.
The main advantages of this type of device are its small size (which makes
it easy to use in developing countries where there are no laboratories, for
example), and its great sensitivity, which would make it possible to detect
cancer in its early stages of development when there is a low density of markers.
Quidant anticipates that the detector will be ready within the next ten years
and that its applications will range from agro-food controls to the detection
of hazardous industrial substances.
Plasmonics: from Gothic stained glass to the laboratory
The discipline of plasmonics underlies most of Romain Quidant's discoveries.
This is actually the “secret ingredient” that, for example, gives
stained glass windows in cathedrals such a distinct color. In fact, stained
glass contains fine metal powder. The interaction of light with the metal electrons
in a metal nanoparticle generates sound waves—plasmons—that display
surprising behavior, such as the ability to emit light and heat in a controlled
This basic phenomenon of physics is the optical response of metal nanoparticles
when they are sent a certain amount of light. For each well-defined type of
light, a nanoparticle has an “optical resonance” that, on the one
hand, generates a very intense, concentrated field of light on its surface and,
on the other hand, heats up the particle. A plasmon is this resonance effect
that characterizes the interaction of light with these nanoparticles, which
results in the intense, localized field and the heat.
From the mirrors used by Archimedes to burn enemy ships to the lasers used
for current diagnoses and treatments, the history of light in technology has
been the adventure of transforming an intangible, short-lived phenomenon into
a powerful and versatile tool. Light has become an indispensable tool whose
many benefits include its use to shape industrial parts; analyze chemical substances;
perform operations to correct short-sightedness, moles and the loss of skin
color; and as a source of clean energy. Its everyday applications include broadband
Internet connections, CD players, barcode readers, printers and even the laser
lights used at concerts.
Light is a leading-edge tool. Future applications include quantum computers
and super-secure encryption, in addition to new nanometric technologies and
minimally invasive systems that interact with live matter.
Romain Quidant (Dijon-France, 1975) earned his PhD in physics at the University
of Burgundy (Dijon) in 2002. Before defending his doctoral thesis, he had already
received offers from four leading European institutions that wanted to take
him on, and from them he chose the UPC's Institute of Photonic Sciences
(ICFO). He is currently a researcher at the ICREA, a Cellex Fellow and the leader
of the plasmon nano-optics group at the ICFO. He leads an international team
of 15 people who are researching the optical and heat properties of metal nanostructures
for biomedical applications. His research is being undertaken in collaboration
with the Cellex Foundation Barcelona.
He also actively collaborates with the company Endor Nanotechnologies, where
he is working on plasmonic applications in the field of cosmetics and dermatology.
Quidant is the author of 50 scientific papers and he has been a guest speaker
at over 20 international conferences.
He was the winner of the Fresnel Prize 2009. He was awarded this prize in June
in the applied sciences category by the European Physics Society, which recognizes
the best researchers under the age of 35 in the fields of optics and quantum
electronics. This is the first time that this prestigious prize has been awarded
to a scientist working in Spain.