- Currently most cancers are detected only in later stages after the disease has spread, making it difficult to treat and achieve cure or remission.
- Novel plasmonic sensor device detects very low concentrations of cancer biomarkers such as carcinoembryonic antigen (CEA), allowing very early detection and treatment.
novel plasmonic sensor device developed by scientists at the University of
Illinois at Urbana-Champaign, enables early detection
of biomarkers for many types of cancer and potentially for several other
diseases as well.
is the Need for Plasmonic Sensing Technology?
Currently, the diagnostic
methods available for detecting cancer and other
biomarkers, are capable of detecting only fairly higher concentrations
of the substance, which tends to be a limiting factor in early
diagnosis. A novel device
developed by the current
research team permits detection of CEA
concentrations as low as 1 nanogram per milliliter
‘Cancer biomarker carcinoembryonic antigen (CEA) can now be detected in very minute concentrations in the blood using a simple, cheap and portable plasmonic sensor device.’
current research team was led by Logan Liu, and Lynford Goddard, associate
professors of electrical and computer engineering and the project was
carried out by students Abid Ameen and Lisa Hackett. The team published their
results in Advanced Optical Materials
as a cover article.
The team chose CEA
because most normal humans have at least 3-5 nanograms/ml and its occurrence in
higher concentrations is an early indicator (biomarker) of many forms of cancer
, including lung and
is one of the major causes of death in the United States as
more than half of the new patients are diagnosed after it has already
spread," Ameen explained. "This shows the gravity with which this
problem needs to be addressed and this new design of a plasmonic sensor helps
to detect the lower concentration of CEA at an earlier state."
importantly, the current device is portable,
cheap and simple to use, not requiring any expertise
to use and make a
measurement and can be used in the
. This would be especially helpful for patients who do not
have access to a tertiary care center or a major facility. A finger prick blood sample
to carry out the test avoiding the use of a vial or tubes to collect the blood.
Plasmonic Sensor Device Incorporating Nanotechnology
device combines the properties of
nanotechnology and a plasmonic sensor
to enable detection of very low
concentrations of the biomolecule with high degree of sensitivity.
nanotechnology involved in the testing
device is an array of metal nano cups or cavities
. The wall of the cavity
is composed of 2 layers of gold surrounding a central insulating layer i.e 3
layered. The test samples to be measured are placed within each cavity.
Unlike normal metal, which will not allow optical
transmission, the nanocup structure allows excellent transmission of light and the
cavity allows light to be stored within
Gold is preferred as the metal for the nanostructure because it is inert
and does not react with substances in the blood.
wall of the cavity is coated with
antibody to the carcinoembryonic antigen
(in this current research).
the blood test sample contains CEA, an interaction between the antigen in the blood and coated
antibody will occur. This interaction leads to an increase in the refractive
of the immediate environment surrounding the nanostructure.
measures the change
in refractive index as seen by a corresponding change in localised surface
plasma resonance (LSPR) wavelength
. The shift in LPSR wavelength that can
be measured by a detector will be directly proportional to the concentration of
the substance in the test sample (CEA in this case).
"By combining plasmonic
properties and the optical cavity properties together in one device we are able
to detect lower concentration of biomarkers by light confinement and
transmission in the cavity layer and from the top of the device respectively,
based on the thickness of the multilayers and the refractive index of the
cavity layer," Ameen explained.
this device, the light source can be an LED instead of a laser and a photocell or
a camera image can be used instead of a high-end spectrometer.
are Surface Plasmons?
is a mixture containing positive ions
and negative electrons
. The electrons rhythmically oscillate back and forth
around the ions, and each individual electron movement is a plasmon.
are those plasmons that
are confined to surfaces and that interact strongly with light resulting in a
plasma resonance wavelength shift that can be measured.
Potential Applications Of The Plasmonic Sensing Technology
the developers point out, the simplicity and easy portability of the
device makes it ideal for use by smaller medical centers at the community
can be done for in the Outpatient Clinic as part of routine checkup for
both diagnosis as well as monitoring post-treatment.
the future by changing the coating antibody on the wall of the cavity
several diseases can be similarly detected at an early stage.
conclude in the words of one of the authors, "In the future, if they are
made very cost-effective and portable," Hackett said, "it would be
great to see people be able to take more control over their health and monitor
something like this on their own."
- Plasmonic Nanostructures for Nano-Scale Bio-Sensing - (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3274321/)