Complete growth medium

ComponentCat. No.
Gibco Ham’s F-12 Nutrient Mix11765054
5% Horse Serum
1 mM Gibco Sodium Pyruvate11360070
25 mM Gibco HEPES15630106

Proper culture techniques and procedures are an essential part of ensuring successful transfection. Subculturing, also referred to as passaging, is the removal of medium and transfer of cells from a culture into fresh growth medium, in order to propagate the cells. See our product list for this protocol


  • Maintain cells in T-75 flasks.
  • Use Gibco TrypLE dissociation reagent.
  • Passage cells every 3–4 days to ensure that they do not enter senescence.
  • Transfection of cells should be performed only between passages 5 and 25 post-thaw.
  • If designing an experiment that involves transfection, ensure that setup coincides with a cell passage.
  • Plate cells for transfection only 1 day before the experiment.

Seeding cells for transfection

  • The day before transfection, dissociate cells that are 80–90% confluent in a T-75 flask.
  • Count the cells using standard trypan blue exclusion.
    • ––Important: The cell number and concentration determined can vary significantly depending on what method is used for counting; it is important to be consistent and use a single method throughout an experiment.
  • The cell culture must have >90% viability and be 80% confluent on the day of transfection.
    • ––Important: If cells are not at the right confluence, do not wait until the next day to perform transfection, as this can significantly affect transfection efficiency.
  • Seed 2 x 105 cells in 500 μL growth medium for a single well of a 24-well plate.

Transfection protocol

On the day of transfection, which should be 1 day following cell plating, perform the following steps, which have been optimized for a single well of a 24-well plate using Invitrogen Lipofectamine 3000 Transfection Reagent:

StepTubeComplexation componentsAmount per well
1Tube 1Opti-MEM I medium25 μL
Lipofectamine 3000 reagent1.5 μL
2Tube 2Opti-MEM I medium25 μL
DNA amount (DNA concentration should be 0.5–5 μg/μL)0.5 μL
P3000™ reagent1 μL
3Add tube 2 solution to tube 1 and mix well
4Incubate mixture from step 3 at room temperature for 10–15 min
5Add 50 μL of complex from step 4 to cells;
gently swirl plate to ensure homogeneous distribution of complex to the entire well

Transfection efficiency analysis

At 48 hr following transfection of a GFP reporter construct, cells were evaluated via microscopy and flow cytometry. To assess transfection efficiency, cells were first visualized via fluorescence microscopy for qualitative assessment of protein expression, morphology, and viability (Figure 1). Cells were then prepared for flow cytometry by aspirating the medium and replacing it with 250 μL of a 7:3 mixture of TrypLE reagent:1X DPBS. Cells were incubated at 37°C for 10 min and then pipetted up and down to ensure single cells for flow cytometry analysis.

Post-transfection analysis of cells

Figure 1. Post-transfection analysis of cells. (A) Fluorescence and (B) bright-field images demonstrating 10–20% transfection efficiency.

Tips and tricks

  • Decreasing the serum content of the culture medium (to <10%) at the time of transfection is acceptable, but replace with complete growth medium within 4–24 hr post-transfection.
  • Antibiotics can be used during transfection.
  • Prior to flow cytometry, visualize cells under a bright-field microscope to verify dissociation following incubation with TrypLE reagent.

Scaling up or down Lipofectamine 3000 reagent transfections

Use the following table to scale the volumes for your transfection experiment. The most common sizes are listed below.

Culture vesselMultiplication factor*Shared reagentsDNA transfectionsiRNA transfection
Growth mediumOpti-MEM medium for complexingDNAP3000 reagentLipofectamine 3000 reagent**siRNALipofectamine 3000 reagent**
96-well0.2100 μL2 x 5 μL0.1 µg0.2 µL0.3 µL3 pmol0.3 µL
48-well0.5250 μL2 x 12.5 μL0.25 µg0.5 µL0.75 µL7.5 pmol0.75 µL
24-well1500 μL2 x 25 μL0.5 µg1 µL1.5 µL15 pmol1.5 µL
12-well21 mL2 x 50 μL1 µg2 µL3 µL30 pmol3 µL
6-well52 mL2 x 125 μL2.5 µg5 µL7.5 µL75 pmol7.5 µL
60 mm11.055 mL2 x 250 μL5.5–11 µg11–22 µL17 µL166 pmol17 µL
10 cm28.9510 mL2 x 500 μL14–28 µg28–56 µL43 µL434 pmol43 µL
T-7539.4715 mL2 x 750 μL20–40 µg40–80 µL59 µL592 pmol59 µL
T-17592.1135 mL2 x 1.75 mL46–96 µg92–180 µL138 µL1,382 pmol138 µL

* After determining the optimum reagent amount, use the multiplication factor to determine the reagent amount needed for your new plate format.
** Optimum amount needed is determined from the protocol for Lipofectamine 3000 Transfection Reagent.

For Research Use Only. Not for use in diagnostic procedures.