Silanization of slides,
In order to achieve good adhesion between the objectglass and the coupe, it is essential that the glass is clean and, above all, free of grease.
Most manufacturers of slides offer pre-cleaned products, but most of the time this is not clean enough.
It is advisable to clean slides again before use, e.g. in a mixture of ethanol and acetone. Wipe dry with a fat and lint free tissue.
Manufacturers usually give their slides an expiration date. It is important to check whether this date has been exceeded before use. In a histological laboratory, the consumption of slides is so high that this will not be a problem, but for the amateur it can easily happen that this date is exceeded. Fine dots of contaminants are then visible on the slide, which can easily be removed in a mixture of ethanol and acetone.
With poorly cleaned slides, coupes in the various stages of dehydration or staining can partially or completely come loose and the coupe is lost.
In most cases, a clean object glass is therefore sufficient to ensure good contact between the coupe and the object glass. However, there are various types of tissue and staining techniques which, despite careful cleaning, can be easily detached. These include: brain tissue, large complex coupes of various tissue types, staining with alkaline liquids, silver impregnation and so on.
The slides can be treated with special media for a better coupe adhesion. Some examples are: protein glycerine, chromium algae gelatine, poly-L-lysine and silanization[1].
Silanization[1],
In the case of slide silanization, a silane bond covalently [2] binds to the surface of the glass and serves as a bonding agent between the object glass and the tissue section. The solution is called (3-Aminopropyl)triethoxysilane [2] (APTES).
Execution[1],
- Dissolve 1ml APTES in 50ml of acetone (for a Hellendahl glass trough: 1.4ml APTES in 70ml of acetone);
- Pour solution into a glass staining tray;
- immerse object glass in the liquid for 20 seconds;
- rinse briefly in clean acetone twice;
- short rinse in AD 2x;
- dry at room temperature or heat cabinet if necessary.
References:
[1] Prof. Dr. Peter Böck (2010, 18., Auflage), Romeis Mikroskopische Technik, München. Verleger: Spektrum Akademischer verlag. Chapter 3, "Färbemethoden" ; paragraaf 3.5.1.3.4, "Beschichtungsmöglichkeiten der Objektträger", page 191.