Staining, Histochemistry and Histotechnology
(Frequently Asked Questions)
Dr. John A. Kiernan
Department of Anatomy
and Cell Biology
The University of Western Ontario
or TES or positively charged) slides
How do I prepare charged or silanized slides in the lab, and is it OK to use metal slide racks?
Silanized slides have a permanent positive charge associated with the glass surface. This attracts negative ions in the section (things like sulfate of cartilage and carboxylate of protein). You can buy silanized slides; they have a variety of trade names and are more expensive than ordinary slides.
It is easy to make your own positively charged slides using APES (also abbreviated to TES). You can buy 3-aminopropyltriethoxysilane from Sigma (St Louis, MO) or from Strem Chemicals (Newburyport, MA) or from Gelest (Tullytown, PA). Keep it in the fridge; let it warm to room temperature before opening the bottle. The solution in acetone deteriorates after one day.
1. Wash slides in detergent for 30 minutes.
2. Wash slides in running tap water for 30 minutes.
3. Wash slides in distilled water, 2 X 5 minutes.
4. Wash slides in 95% alcohol 2 X 5 minutes.
5. Air dry for 10 minutes.
6. Immerse slides in a freshly prepared 2% solution of
3-aminopropyltriethoxysilane in acetone for 5 seconds.
7. Shake off excess liquid and wash briefly in distilled
8. Dry overnight at 42C and store at room temperature.
300 ml of silane solution is sufficient to do 200 slides.
Treated slides can be kept indefinitely.
University of Nottingham
(With additions and minor editing by J. A. Kiernan, London, Canada).
As far as I know, the notion that you must do TES treatment in glass slide trays is another urban myth! We coat thousands of slides annually in metal racks with nary a problem.
Bryan Hewlett (CMH)