Staining, Histochemistry and Histotechnology
(Frequently Asked Questions)
Dr. John A. Kiernan
Department of Anatomy
and Cell Biology
The University of Western Ontario
For how long can you store a solution of poly-L-lysine used as a section adhesive for slides? For how long can you store the coated slides? Do you get autofluorescence? Do you have to use poly-L-lysine, or will the cheaper poly-DL-lysine work equally well?
I use a 1:10 dilution in PBS of Sigma's stock poly-L-lysine solution (P-8920). Slides sit in the solution for 4 hours (or more if you choose/it is more convenient) and air dry overnight. This has worked for us without ever a section lost. The poly-L-lysine solution (undiluted from Sigma) says it expired in 1996, but it still worked in summer '97. I have never noticed any autofluorescence.
I have switched to Superfrost Plus slides; when counting in time to put slides in racks to dip and the time to rebox them, it is more cost-effective for us to buy the superfrost plus.
Noelle Patterson, M.S.
Bethesda, MD 20889
The type of polylysine does not matter, so get the cheapest, which is usually the mixed (DL) enantiomers rather than the pure L- form. The reagent and the slides should keep for ever if they don't get infected with micro-organisms or contaminated with dust.
For a simple way to prepare polylysine-coated slides, see Thibodeau, T. R., Shah, I. A., Mukherjee, R. & Hosking, M. B. 1997. Economical spray-coating of histologic slides with poly-L-lysine. Journal of Histotechnology 20(4): 369-370.
They stated that it was economical and quick to spray polylysine solution on one side of the slides from a simple plastic spray bottle. Results were no worse than dipping, which was more trouble. They used a 1:10 dilution of PLL solution but did not state the concentration, molecular weight or source.