Substrates

Choice of substrate for Raman spectroscopy is critical for different bio-imaging applications. As Raman spectra are inherently weak, it is important to minimize any background signal produced by the substrate. Substrates typically display wavelength-dependent spectral responses. In general, the choice of substrate needs to take into consideration both the excitation laser wavelength, substrate bio compatibility, and cost [1-6].

The key substrates used in Raman bio-imaging applications are:

• Glass
• Magnesium Fluoride (MgF2)
• Raman grade Calcium Fluoride (CaF2)
• Tissue Culture Plastic
• Aluminum [6]
• ​Steel [4]

References:

1. Meade, A. D., Lyng, F. M., Knief, P., Byrne, H. J., Analytical and Bioanalytical Chemistry, 387, 5, 2007.
2. Draux, F., Jeannesson, P., Beljebbar, A., Tfayli, A., Fourre, N., Manfait, M., Sule-Suso, J., Sockalingum, G. D., Analyst, 134, 2009.
3. Kerr, L. T., Byrne, H. J., Hennelly, B. M., Analytical Methods, 7, 2015.
4. Lewis, A. T., Gaifulina, R., Isabelle, M., Dorney, J., Woods, M. L., Lloyd, G. R., Lau, K., Rodriguez-Justo, M., Kendall, C., Stone, N., Thomas, G. M., Journal of Raman Spectroscopy, 48, 2017.
5. Butler, H. J., Ashton, L., Bird, B., Cinque, G., Curtis, K., Dorney, J., Esmonde-White, K., Fullwood, N. J., Gardner, B., Martin-Hirsch, P. L., Walsh, M. J., McAnish, M. R., Stone, N., Martin, F. L., Nature Protocols, 11, 4, 2016.
6. Cui, L., Butler, H. J., Martin-Hirsch, P. L., Martin, F. L., Analytical Methods, 8, 2016.

Microscope glass slides

Spectrum

Coming soon.

Details

Glass is a common and easy-to-use substrate, suitable for a range of cell studies. However, while glass works well from a biological point of view for cells or thin tissue sections, glass background signal can confound some analyses. Glass is poorly compatible with NIR excitation such as 785 lasers due to their poor confocal sectioning capability and intense photoluminiscence. However, in a proper confocal Raman setup with 532 nm excitation and a high magnification objective (e.g., 60x) glass slides should give no background.

Performance

Background
​Bio-compatibility
Cost 
​

5/10
8/10
10/10

Magnesium Fluoride (MgF2)

Spectrum

Coming soon.

Details

MgF2, displays very low Raman signal background. For advanced biology, researchers should be aware of limitations in bio-compatibility.

Performance

Background
​Bio-compatibility
Cost 
​

10/10
7/10
2/10

Raman grade Calcium Fluoride (CaF2)

Spectrum

Coming soon.

Details

Raman grade CaF2 has long been the Raman substrate of choice due to its very low background signal, with a single sharp peak at 321 cm-1, and its good biocompatability.

Performance

Background
Bio-compatibility 
​Cost
​

10/10
7/10
​2/10

Tissue Culture Plastic

Spectrum

Coming soon.

Details

Tissue culture plastic is a cheap and versatile substrate suitable for a range of biological studies. For Raman imaging, however, it gives significant background signal that will confound many analyses.

Performance

Background
​Bio-compatibility
Cost 

1/10
9/10
10/10

Stainless Steel

Spectrum

Coming soon.

Details

Mirrored stainless steel has recently been shown to provide a good substrate while still having a very low background signal. Reflection of laser light and Raman generated photons can generally increase the signal detected.

Performance

Background
​Bio-compatibility
Cost 
​

7/10
2/10
10/10

Aluminum

Spectrum

Coming soon.

Details

A recent study has demonstrated that aluminum foil can be used for cell culture and provides a remarkable low background signal at a fraction of the cost of MGF2/CaF2. Nonetheless, as with stainless steel, biocompatibility is low

Performance

Background
​Biology 
​Cost
​

8/10
2/10
10/10