Addressable graphene encapsulation of wet specimens on a chip for optical, electron, infrared and X-ray based spectromicroscopy studies
Label-free spectromicroscopy methods offer the capability to examine complex cellular phenomena. Electron and X-ray based spectromicroscopy methods, though powerful, have been hard to implement with hydrated objects due to vacuum incompatibility of the samples and parasitic signals from (or drastic attenuation by) the liquid matrix surrounding the biological object of interest. Similarly, for many techniques that operate at ambient pressure, such as Fourier Transform Infrared spectromicroscopy (FTIRM), the excessive aqueous environment imposes severe limitations due to the strong absorption by liquid water in the infrared regime. Here we propose a microfabricated multi-compartmental and reusable hydrated sample platform for several analytical techniques, which uses the conformal encapsulation of biological specimens by atomically thin graphene. Such an electron, X-ray, and infrared transparent, molecularly impermeable and mechanically robust enclosure preserves the hydrated environment around the object for a sufficient time to allow in-situ examination of hydrated bio-objects with techniques operating both in ambient or high vacuum conditions. An additional hydration source, made by hydrogel pads patternable on/around the specimen and co-encapsulated, has been added to further extend the hydration lifetime. Scanning electron and optical fluorescence microscopies as well as synchrotron radiation based FTIR and X-ray fluorescence microscopies have been used to test the applicability of the platform and for its validation with yeast, A549 human carcinoma lung cells and micropatterned gels as biological object phantoms.
Addressable graphene encapsulation of wet specimens on a chip for optical, electron, infrared and X-ray based spectromicroscopy studies, Lab on A Chip, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932110
(Accessed September 23, 2023)