Photoelectron microscopy of cell surfaces.

Area of Science:

• Biophysics
• Biochemistry
• Microscopy

Background:

• Photoelectron microscopy offers high-resolution imaging of biological samples.
• Understanding the optical properties of biological molecules is crucial for imaging contrast.

Purpose of the Study:

• To characterize the photoelectron quantum yields of various saccharides.
• To investigate the imaging capabilities of photoelectron microscopy for unstained biological cells.
• To determine the primary source of contrast in photoelectron micrographs of fibroblasts.

Main Methods:

• Acquisition of photoelectron micrographs of fixed, unstained, uncoated chicken embryo fibroblasts.
• Measurement of absolute photoelectron quantum yields for L-fucose, D-galactose, D-glucose, N-acetyl-D-glucosamine, and Ficoll in the 180-230 nm wavelength band.
• Comparison of saccharide quantum yields with a reference dye (phthalocyanine) and previously reported values for amino acids and phospholipids.

Main Results:

• Low photoelectron quantum yields were measured for the studied saccharides, comparable to amino acids and phospholipids.
• Photoelectron micrographs revealed significant surface detail of the unstained and uncoated fibroblasts.
• The quantum yield data and micrographs collectively suggest that surface topography is the main contributor to image contrast.

Conclusions:

• Saccharides exhibit low photoelectron quantum yields, similar to other biomolecules.
• Photoelectron microscopy can visualize surface details of biological cells without staining or coating.
• Surface relief is the dominant factor for contrast generation in photoelectron imaging of these cells.