High-resolution and 3D imagery are now possible with advanced microscopy and other instruments, but the The CYTOP® nanosheet developed by the researchers. Source: Zhang H. et al., Advanced Materials, August 11, 2017drying and deformation of biological samples, and the resulting blurring of images, remains a problem.

Researchers in Japan theorized that if plastic wrap keeps food from desiccating, why not wrap biological tissues? A nanosheet based on a transparent amorphous fluoropolymer was developed and tested for its effectiveness in generating clear images when wrapped around tissue samples. The team, composed of scientists from Hokkaido University and Tokai University, fabricated a nanosheet of CYTOP^®, a commercially available chemical agent developed by Asahi Glass Co., by spreading its solution on a layer of poly-vinyl-alcohol. The material retained the chemical agent’s water-repellent properties, which should maintain a sample’s water content when applied as a wrapper.

After wrapping an alginate hydrogel to simulate biological samples, the researchers observed that the gel retained 60 percent of its water content after 24 hours; unwrapped samples were totally dehydrated after 10 hours. A 133-nanometer-thick sheet provided sufficient water retention and surface adhesion.

Additional tests were conducted with 1-millimeter thick brain slices from mice. Without the wrap, evaporation of embedded water caused local, non-uniform sample shrinkage, leading to blurred images. After wrapping samples with a CYTOP^® nanosheet, images with a high spatial resolution were obtained from scanning a large area (more than 750-by-750 micrometers) over about two hours. Similar results were documented when the sample was embedded in agarose gel — a common technique used for mounting biological tissues that could disturb the clarity of transparent samples — without disturbing the clarity.