PEI 1 mg/mL (linear, 25 kDa) transfection reagent recipe
An inexpensive, efficient transfection reagent widely used in HEK293-type cells for virus and protein production. DNA : PEI = 1 : 3 by weight.
🧮 Volume calculator
| Component | Amount | Final concentration (1X) |
|---|---|---|
| Linear PEI (MW 25,000) | 50 mg | 1 mg/mL |
| Water (distilled) | to final volume |
Steps
- Add PEI to about 80% of the final volume of water and lower the pH to ≈2 with HCl to dissolve (or heat to 60–80 °C).
- Once dissolved, neutralise to pH 7.0 with NaOH and bring to volume.
- Filter-sterilise through 0.22 µm. Aliquot and store at −20 °C (or −80 °C).
Good to know
- Dilute DNA and PEI separately in serum-free medium, combine, wait 15–20 min and add to cells.
- Thawed stock lasts weeks at 4 °C; repeated freeze–thaw lowers efficiency.
FAQ
Is it the same as branched PEI?
No — most protocols are based on linear 25 kDa PEI (or the 40 kDa hydrochloride form).
This is a widely used standard composition. Amounts depend on the hydrate form and purity of your reagents — check the formula weight (FW) on the bottle and follow your institution's safety rules and the manufacturers' instructions.