New technology opens to a whole new set of investigations of biological wet samples

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Characterisation of the hydrated specimen, using advanced spectroscopic and microscopic methods, is crucial in understanding biological processes occurring under natural physiological conditions.  However, many of these powerful techniques, such as electron microscopy, photoelectron, soft X-ray, and infrared spectromicroscopy, are incompatible with aqueous media due to vacuum requirements or very strong absorption of the infrared light by water molecules. The CERIC internal research project RENEWALS, led by Maya Kiskinova and Lisa Vaccari (Elettra Sincrotrone Trieste), has overcome the limitations of studying hydrated biological specimens by the development of Graphene Liquid Cells (GLCs), using photon and electron transparent and water-impermeable graphene membranes.

Most recently, a group from NIST (National Institute of Standards and Technology), led by Dr. Andrei Kolmakov, that included Christopher Arble (NIST), Dr. Alessia Matruglio (NIST guest researcher from CERIC-ERIC), and other collaborators from Elettra Sincrotrone Trieste co-authored a study reporting the most recent advances in fabrication and performance of a graphene encapsulation liquid cells, suitable for in-situ studies of hydrated biological samples with a broad array of analytical methods. They demonstrated successful characterisation of a variety of specimens, including mammalian and yeast cells, using multiple techniques, including SEM, fluorescence microscopy, X-ray fluorescence and Fourier Transform Infrared Spectromicroscopy at the TwinMic and the SISSI beamlines at the Italian CERIC Partner Facility, Elettra Sincrotrone Trieste.

A microchip for correlative spectromicroscopy of biological material in a hydrated state employs a few layers of thin graphene membrane to separate wet samples from a vacuum environment. Enhancement of water retention time has been achieved by lithographically adding hydrogel co-encapsulated microstructures

The new platform has allowed retaining the hydrated state of the sample long enough to enable X-ray fluorescence experiments, which typically take a few hours for a single-cell map and require high-vacuum conditions. These achievements are opening the road to a new type of measurements with different samples in a liquid environment.

ORIGINAL ARTICLE:

ADDRESSABLE GRAPHENE ENCAPSULATION OF WET SPECIMENS ON A CHIP FOR OPTICAL, ELECTRON, INFRARED, AND X-RAY BASED SPECTROMICROSCOPY STUDIES, ARBLE C., GUO H., MATRUGLIO A., GIANONCELLI A., VACCARI L., BIRARDA G., & KOLMAKOV A., LAB ON A CHIP, 2021.