How to use self-adhesive film with easy-to-follow steps


It may look simple, but if PCR plates are not properly sealed, your time, expense and hard work could go to waste. It is worth investing a little time to understand all you need to know to get it right every time.

PCR plates accelerate research by allowing analysis of a large number of samples in a quicker time frame. Each microplate can hold a range of different samples within its wells, so it is essential to protect the contents from cross-contamination as well as contamination from the external environment. Correctly used sealing films can achieve this and prevent evaporation.

Which is the best sealing material for PCR plates?

Choosing the right material to seal your microplate requires consideration of the type of plate being used and the sample within its wells as well as the processes it will undergo and equipment specifications. You may also develop a preference based on experience. In preparation, ask yourself: Will you need to access some or all the wells during processing steps? Does the seal need to be transparent e.g. for optical applications? What length of time does the seal need to stay viable? How reactive are the substances within the wells? What temperatures will the seal experience? How tight do the seals need to be?  

Film seals and foil seals, pros and cons

Film seals are a thin plastic layer with an additional coating that is either adhesive or that melts when heat is applied to form a tight seal with the rims of each well. Film seals are a good choice for optical analysis as they are transparent and robust enough to protect samples and prevent evaporation. Film seals are appropriate for PCR and qPCR. Film seals are not recommended for storage below -80℃. If you need long term storage of samples, heat sealing film is a good choice as the heat creates a very robust seal. Foil seals provide the same level of protection, they are a good choice if you don’t need to observe the samples during processing. Foil seals can be punctured individually so are perfect if contents of individual wells need to be accessed. Foil is also best for storage of light-sensitive samples.

How is self-adhesive microplate sealing film applied?

For films and foils that have an adhesive coating, the trick is to apply pressure evenly across the whole plate ensuring a tight seal on each well. This can be achieved manually.

  1. Place your plate on a flat, stable surface
  2. Remove backing from the seal
  3. Place the seal over the plate, ensuring all wells are covered
  4. Starting at one end and using the quick seal roller to apply even pressure across the plate.
  5. Apply the pressure repeatedly along the length and width of the plate
  6. Some adhesive film seals become fully sealed once heated during processes like thermocycling.

Using a heat sealer

Heat sealers can be used with film or foil seals and will create a very tight seal by melting the film to the rim of each well. They are fast, reliable and should work with shallow and deep plates, tube racks and custom mouldings. Fully automated models can be programmed to alter sealing time, pressure, temperature, size and distance to be sealed, all customisable to suit a wide range of applications. Heat sealing is particularly appropriate for long-term storage of samples.   Whatever your choice of material, it needs to be effective and watertight, always source them from a reputable supplier.