Biosensors: Sweet and simple

Apr 14, 2011 By Lee Swee Heng

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 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 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 sensing.

Explore further: Researchers have developed a diagnostic device to make portable health care possible

More information: Dinish, U. S., et al. Development of highly reproducible nanogap SERS substrates: Comparative performance analysis and its application for glucose sensing. Biosensors and Bioelectronics 26, 1987–1992 (2011).

Provided by Agency for Science, Technology and Research (A*STAR)

4.7 /5 (3 votes)
add to favorites email to friend print save as pdf

Related Stories

Securing the nation with fingerprinting materials

Nov 09, 2010

Lawrence Livermore National Laboratory researchers may have found a way to improve Raman spectroscopy as a tool for identifying substances in extremely low concentrations. Potential applications for Raman ...

ORNL nanoprobe creates world of new possibilities

Jul 15, 2004

A technology with proven environmental, forensics and medical applications has received a shot in the arm because of an invention by researchers at the Department of Energy's Oak Ridge National Laboratory. ORNL's nanoprobe, which ...

Study shows nanoshells ideal as chemical nanosensors

Jan 11, 2005

'Nanoshells' enhance sensitivity to chemical detection by factor of 10 billion New research published in the Proceedings of the National Academy of Science finds that tailored nanoparticles known as nanoshells can enhanc ...

Recommended for you

Chemical biologists find new halogenation enzyme

11 hours ago

Molecules containing carbon-halogen bonds are produced naturally across all kingdoms of life and constitute a large family of natural products with a broad range of biological activities. The presence of halogen substituents ...

Protein secrets of Ebola virus

16 hours ago

The current Ebola virus outbreak in West Africa, which has claimed more than 2000 lives, has highlighted the need for a deeper understanding of the molecular biology of the virus that could be critical in ...

Protein courtship revealed through chemist's lens

16 hours ago

Staying clear of diseases requires that the proteins in our cells cooperate with one another. But, it has been a well-guarded secret how tens of thousands of different proteins find the correct dancing partners ...

Decoding 'sweet codes' that determine protein fates

18 hours ago

We often experience difficulties in identifying the accurate shape of dynamic and fluctuating objects. This is especially the case in the nanoscale world of biomolecules. The research group lead by Professor Koichi Kato of ...

Science to the rescue of art

Sep 14, 2014

Vincent van Gogh's "Sunflowers" are losing their yellow cheer and the unsettling apricot horizon in Edvard Munch's "The Scream" is turning a dull ivory.

User comments : 0