2001 Volume 18 Issue 1 Pages 1-7
Variable Pressure Scanning Electron Microscopy (VP-SEM) with a cooling stage allows the observation of water-containing wet samples with minimum shrinkage or deformation without conventional sample preparations such as fixation, dehydration, drying, and metal-coating. The VP-SEM with a cooling stage also reduces water vaporization and electron beam damage, so it will enable us to make an observation for a long time.
We studied white radish sprouts using the VP-SEM with the cooling stage and a Yttrium Aluminum Garnet (YAG) backscattered electron detector for better image quality at various accelerating voltages. In addition to non-cleaned samples, the following three cleaning techniques for the samples were examined: 1) Cleaning by running tap water; 2) Dipping in strongly acidic electrolyzed water and cleaning by running tap water; 3) Dipping in formula consisting mainly of fumaric acid and cleaning by running tap water.
A low accelerating voltage of 5 kV made it easy to recognize bacteria on the samples. The fairly large tissue surfaces of non-cleaned samples were covered by bacteria and the bacteria were lined up along the grooves of cell boundaries. Running tap water did not markedly remove bacteria from the surface of the samples. On the other hand, strongly acidic electrolyzed water or formula consisting mainly of fumaric acid showed a marked cleaning effect. Moreover, the bacteria along the grooves of cell boundaries of those stuck to the surface of cells remained in spite of cleaning.
