New substrate for surface enhanced Raman spectroscopy (Sers) enables faster, higher accuracy analysis of biological and chemical samples at lower detection limits
On 19 September 2005 a research team from the University of Michigan announced the initial findings of a project that could lead to early-stage diagnosis of osteoarthritis.
The project, funded by the US National Institute of Health, is investigating ways to use surface enhanced raman spectroscopy (Sers), to identify levels of hyaluronic acid (HA) within a blood sample.
If successful, detection of the disease would be possible before mechanical damage to the knee occurs, eliminating the need for long-term pain management.
The research has been made possible through the development of a new Sers substrate, called Klarite.
Launched in January 2005 by Mesophotonics, Klarite enables faster, higher accuracy analysis of biological and chemical samples at lower detection limits.
As a result, gluconate and glucosamine, which make up the polymer in HA can now be detected.
"Gluconate and glucosamine only achieve very weak Raman scatters and were impossible to identify on previous Sers substrates," explains Professor Mike Morris, who heads up the project for the Muscular Skeletal Disorder Unit at the university.
"The signals generated by the Klarite substrate are many orders of magnitude more intense than traditional Raman signals, making research projects such as this possible".
Offering unparalleled levels of reproducibility, according to Mesophotonics, Karlite substrates are mounted on standard 3" glass slides, allowing the unique Raman fingerprint in all molecules to be easily and repeatedly identified.
Compatible with existing Raman instruments, Klarite has significant implications for researchers in a variety of pharmaceutical and biomedical areas as well as in forensics, homeland security and analytical chemistry.
The initial phase of the research, which was presented at a Royal Society of Chemistry event on 19 September, shows that there is the potential to develop a candidate for a bio-marker for osteoarthritis.
This could potentially enable clinicians to include a test for HA within a normal blood work up.
Klarite substrates provide a unique tool for surface enhanced Raman spectroscopy (Sers).
Unrivalled levels of Raman signal reproducibility are obtained by using these substrates.
Klarite substrates feature a systematically designed nanometre scale patterning of the gold surface.
Made of regular arrays of holes, the surface patterns form photonic crystals which control the surface plasmons that govern the Sers amplification.
By leveraging its experience in photonic crystal design, Mesophotonics is able to control the surface plasmon effects and therefore control the Raman amplification.
Reproducibility is built into Klarite slides by using volume manufacturing procedures from the semiconductor industry.
Tests have shown relative standard deviations (RSD) of less than 15% are achieved with only 5mW excitation at 633nm or 785nm.
This includes all variations between different chips without any data selection or filtering.
Across a single chip, variations of just 6% RSD have also regularly been recorded.
Klarite substrates are mounted on standard 75x25mm microscope glass slides compatible with most micro Raman spectrometers.
The active area is 5x5mm, with larger areas available on request.
