Home › Cell Biology › Plasmid DNA Transfection Protocol
Steps
  1. 1 Prepare workspace and cells 00:06
  2. 2 Gather materials and equipment 00:36
  3. 3 Prepare lipofectamine dilutions 01:22
  4. 4 Prepare plasmid DNA complex 01:47
  5. 5 Combine DNA with lipofectamine 02:12
  6. 6 Transfect cells with complexes 02:30
  7. 7 Incubate and assess transfection 02:57
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Plasmid DNA Transfection Protocol

Protocol
Difficulty
intermediate

Steps

1
Prepare workspace and cells

Clean the cell culture hood and work surface with 70% ethanol. Seed cells 24 hours prior so they reach 70-90% confluency at the time of transfection.

▶ 00:06
2
Gather materials and equipment

Assemble all required materials including lipofectamine LTX and plus reagent, Optimum reduced serum medium, plasmid DNA (1 microgram per microliter), microcentrifuge tubes, pipettes, marker, timer, and 24-well plate with confluent cells.

▶ 00:36
3
Prepare lipofectamine dilutions

Prepare four tubes with 50 microliters of Optimum medium each. Add increasing volumes of lipofectamine LTX (2, 3, 4, and 5 microliters to tubes 1-4 respectively) and vortex each tube well.

▶ 01:22
4
Prepare plasmid DNA complex

Prepare a separate tube with 250 microliters of Optimum medium, add 5 microliters of plasmid DNA (5 micrograms), then add 5 microliters of plus reagent and mix well.

▶ 01:47
5
Combine DNA with lipofectamine

Add 50 microliters of the diluted DNA solution to each of the four lipofectamine LTX tubes (1-4). Incubate the complexes for 5 minutes at room temperature.

▶ 02:12
6
Transfect cells with complexes

Remove the 24-well plate from the incubator and add 50 microliters of each DNA-reagent complex from tubes 1-4 to the corresponding wells 1-4. Return the plate to the incubator.

▶ 02:30
7
Incubate and assess transfection

Grow cells for 1-3 days at 37°C. View GFP fluorescence using a fluorescent microscope or imaging station to assess transfection efficiency in each well and identify the optimal reagent concentration.

▶ 02:57

🚨 Failure Case Library (11) + Submit your own case

critical
Massive cell death after transfection — reagent toxicity is too high
Cells become rounded and detached after transfection; CCK-8 shows a sharp drop in viability vs. mock-transfected control.
💡 4 · ✓ 4
critical
Almost no fluorescence signal — transfection essentially failed
Under the fluorescence microscope, no GFP signal is visible; Western blot also shows essentially no target protein expression.
💡 5 · ✓ 5
severe
Very few cells are fluorescent — transfection efficiency is extremely low
Microscopy shows scattered positive cells; flow cytometry confirms positivity rate is very low (< 5 %).
💡 5 · ✓ 5
severe
Very Low Transfection Efficiency
Transfection efficiency is significantly lower than expected with poor gene expression
💡 7 · ✓ 9
severe
Cytotoxicity After Transfection
Reduced cell viability and cell death observed following transfection procedure
💡 7 · ✓ 7
severe
Low/No Signal from Insufficient Protein Expression
No detectable signal in IP experiment. Input lysate control shows weak or absent target protein band on western blot.
💡 4 · ✓ 4
moderate
Co-transfection ratio imbalance — uneven dual-plasmid expression
Of two co-transfected plasmids, only one expresses strongly; the fraction of double-positive cells is low.
💡 5 · ✓ 4
moderate
Lipid Reagent Accidentally Frozen
Transfection reagent was frozen instead of stored at 4°C, potentially affecting performance
💡 2 · ✓ 3
moderate
Transfections Not Reproducible
Transfection efficiency shows high variability between experiments and among replicates
💡 5 · ✓ 7
minor
Granular Precipitate on Cells
Small granular precipitate visible microscopically on cells after adding transfection complexes
💡 3 · ✓ 4
minor
Orange Background Fluorescence with GFP
Light granular orange background fluorescence observed after GFP transfection with Lipofectamine 2000
💡 3 · ✓ 3
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