PEI Stocks
Materials
Linear PEI (located in “Chemicals” tray in Oaken 4ºC)
Hydrochloric acid (HCl), to balance pH
Elga water
0.22 µm filter (recommended 500 mL size)
Warning
Ensure you use the linear PEI, not the branched version!
Dissolve and Aliquot PEI
Before beginning, rinse all glassware and stir bar with Elga water.
In a beaker on a stir plate, combine 1 mg PEI powder per 1 mL Elga water.
While stirring, slowly add HCl to dissolve the PEI and achieve a final pH of 7.0.
PEI will not dissolve well in a basic solution, so slowly add acid to facilitate this process.
Add acid a few drops at a time to not overshoot. Total acid required is ~1 mL of 2.5M HCl.
After each addition, wait several minutes for the solution to stabilize. After pH 7.0 is reached, wait an extra 10 min to ensure the pH has not drifted.
In a BSC, filter sterilize the PEI solution through a 0.22 µm filter (the 500 mL ones are appropriate).
Make 1 mL aliquots of PEI in sterile 1.7 mL Eppendorf tubes.
Store the aliquots in Elsa (-80ºC, top shelf). Determine the optimal PEI ratio before use.
Test PEI Ratio
Warning
TODO