Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive and versatile analytical tool that is widely used in biosensing applications. In conventional Raman spectroscopy, molecules are detected by their characteristic scattering of laser light, but the sensitivity of the standard method is relatively low.
By detecting the same Raman scattering from molecules adsorbed to rough metal surfaces, however, the sensitivity can be enhanced remarkably, even allowing the detection of single molecules (see image). Unfortunately, the mechanism of this enhancement is not well understood and is strongly dependent on the combination of surface and molecular target.
Malini Olivo and co-workers at the A*STAR Singapore Bioimaging Consortium and Institute of Microelectronics have now developed a new class of surface that provides a much-needed sensitivity enhancement for the detection of glucose. The new substrate promises the fast, direct and accurate detection of glucose in solution at physiological concentrations.
Olivo and her co-workers have been investigating SERS for the measurement of glucose in biological samples. Glucose has very low Raman scattering efficiency and existing substrates for SERS fail to bring the method’s sensitivity of detection up to a level suitable for detecting the typical concentrations in real samples.
Instead of the commonly used rough metal substrates, the researchers turned to silicon, which they etched to form a well-defined pattern of nanogaps. They then coated the patterned silicon with thin layers of silver and gold. In tests comparing the new substrate with commercial substrates for glucose detection, Olivo and her team found that the silicon-based substrate gave the sensitivity boost they were looking for, which they attribute to the uniformity of roughness provided by the nanogap pattern.
“We were actually very surprised by our substrate’s high reproducibility,” say Olivo. “The best reproducibility reported previously for glucose was only about 10%. However, due to the special design and pattern of our substrate, we achieved reproducibility of about 3–4%, which is outstanding.” The nanogap substrate also provided good sensitivity for the detection of glucose in the physiologically important 0–25 millimolar range.
Olivo and her co-workers are already building on their success with work on an analogous system for sensing proteins. “We would like to translate similar SERS substrate platforms to optical fibers in order to develop a minimally invasive in vivo SERS platform for clinical diagnostics,” she says. The researchers have high hopes that small sensors based on this SERS platform may one day be implanted into patients for real-time glucose sensing.
The A*STAR-affiliated researchers contributing to this research are from the Singapore Bioimaging Consortium and the Institute of Microelectronics
 Dinish, U. S., Yaw, F. C., Agarwal, A. & Olivo, M. Development of highly reproducible nanogap SERS substrates: Comparative performance analysis and its application for glucose sensing. Biosensors and Bioelectronics 26, 1987–1992 (2011).
Rutgers scientists discover 'Legos of life'
23.01.2018 | Rutgers University
Researchers identify a protein that keeps metastatic breast cancer cells dormant
23.01.2018 | Institute for Research in Biomedicine (IRB Barcelona)
Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.
Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image...
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
23.01.2018 | Life Sciences
23.01.2018 | Earth Sciences
23.01.2018 | Physics and Astronomy