Selection of Preparation Techniques Based on Material Problems and TEM Analyses - Sample Preparation Topic for Transmission Electron Microscopy - page 194

Table 7.8 Selection of the preparation technique for bulk biological materials

Biological Material
Bulk Soft, Bulk Hard Tissue

Type of Analysis
Morphology, Labeling, Chemical Analysis

Immunolabeling

Fixation Method
Chemical Physical

Immunolabeling

Specific treatment of Hard
Sample

Dehydration Method
Substitution Freeze Substitution
at 293K Freeze-Drying

Infiltration
Epoxy or acrylic Lowicryl

Cryo-Ultramicrotomy

Ultramicrotomy

Immunolabeling

Selection of a
Positive contrast

Freeze-Fracture

Observation at 293K Cold Observation

Room Temperature Low Temperature

Surface investigations will involve replica techniques.
Investigations of interfaces and volume will involve all of the direct preparation
techniques for materials science (electrochemical, chemical, mechanical, or ionic
thinning). Tables 7.2, 7.3, 7.4, 7.6, 7.7, 7.8, and 7.9 summarize the different options
available. Tables 7.2, 7.3, and 7.4 summarize all of the preparation techniques possi-
ble based on the physical state of the material. Table 7.7 presents the most common
options for materials in materials science. Tables 7.8 and 7.9 summarize the main
techniques possible for fine particles or bulk biological materials.
In biology, the preparation techniques are the result of a complex set of steps.
There are two major preparation pathways: using chemical reactions that occur at
room temperature and through physical procedures to freeze water that are car-
ried out at low temperatures. Most morphological investigations are undertaken
using chemical procedures; physical procedures are more difficult to carry out and,
therefore, are reserved for investigations of molecules (isolated particles) and their