New packaging nanosheets for high-quality bioimaging

CYTOP® nanosheets developed in the study Source: Hong Zhang et al

According to cosmology and biology, the progress of science depends to a large extent on the progress of measuring instruments and methods. Over the past few decades, scientists’ enthusiasm for invisible things has been greatly enhanced by microscopes and other devices, resulting in high-resolution images, three-dimensional images, and longer biological sample recording times. However, the current setting does not prevent the sample from drying and deforming during the observation, which ultimately results in an image blur.

Scientists from Hokkaido University and Tokai University in Japan developed a nanosheet made of a fluoropolymer (known as CYTOP®) and studied the effectiveness of producing clear images when wrapped in biological samples. CYTOP® is a commercially available chemical reagent developed by Asahi Glass Co., Ltd.

The researchers successfully prepared a CYPOP® nanosheet by spreading its solution on a polyvinyl alcohol (PVA) layer. By immersing them in water, the nano thin layer of CYTOP® is easily detached from the PVA layer. The nanoplatelet thickness can be adjusted by changing the concentration of its solution. The nanosheets retain the high water resistance of CYTOP® and, when used as a package, should help retain the moisture content of the sample.

Next, the team tested nanosheets' wrapping performance by using alginate hydrogels to simulate biological samples such as tissue. They found that the gel retained 60% of its water content after being wrapped for 24 hours, and after about 10 hours, the gel gel became completely dehydrated. After experimenting with various thicknesses, they found that a 133 nm thick sheet provided sufficient water retention and surface adhesion, which is necessary to fix the sample on the cover glass.

They immediately followed a practical biological sample: brain sections of a 1 mm thick mouse. Without the CYTOP® package, the evaporation of the internal water causes local, non-uniform sample shrinkage, leading to image blurring. However, by wrapping brain slices in CYTOP® nanoplatelets, images with high spatial resolution can be obtained by long-term (about 2 hours) large-area scanning (greater than 750 μm×750 μm). Even though the sample was embedded in an agarose gel, similar results were obtained - common techniques for increased biological tissue may interfere with the transparency of the sample without affecting the clarity.

"Packaging technology is still in its early stages, but it has established and validated the superiority of nanosheet packaging for tissue imaging," said the researchers who published the paper on AdvancedMaterials.