Questions.

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?

Answer 1.

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.
NNMC/NMRI/ICBP
Bethesda, MD 20889
(pattersonn[AT]nmripo.nmri.nnmc.navy.mil)

Answer 2.

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.

John Kiernan,
(kiernan[AT]uwo.ca)