What recommendations do you have for preparing PEI for Axion Maestro MEA use with iCell Neurons and iCell DopaNeurons?

Follow our Application Protocol instructions to prepare the 0.05 - 0.1% polyethyleneimine (PEI) extracellular matrix (ECM) solution in a borate buffer and the 48-well MEA Plate. Note that preparation of the PEI solution is extensive. To dissolve the borate buffer components (boric acid/sodium tetraborate), you may need to heat the solution at 60°C to 70°C for 3 to 4 hours or longer. After adjusting the borate buffer to pH to 8.4, pass the borate buffer through a 0.22 µm filter to ensure that there is no precipitant. Use the borate buffer to dilute the 50% PEI solution to a final concentration of 0.05 - 0.1% PEI and pass the PEI coating solution through a 0.22 µm filter. The final 0.05 - 0.1% PEI solution can be stored at 4°C for up to 1 month (do NOT store at –20°C).

Preparing the 48-well MEA Plate

  1. Add 125 µl/well of 0.05 - 0.1% PEI solution to the 48-well MEA plate and incubate at room temperature for 1 hour. Note that PEI coated plates can be wrapped in Parafilm sealant and stored (where/what temp?) for up to 5 days before use.
  2. Aspirate the PEI solution from the 48-well MEA plate. Do not allow the wells to dry.
  3. Rinse wells of the 48-well MEA plate 4 times with at least 300 µl/well of sterile water.  Note that PEI is VERY toxic and must be rinsed thoroughly.
  4. Air-dry the 48-well MEA plate with the lid off in a sterile biological safety cabinet overnight. Note that it is essential to allow the 48-well MEA plate to air-dry overnight to achieve optimal cell attachment and maximal performance and to ensure that NO UV light will be turned on during the drying period.


  1. Application Protocol: Measuring Neuronal Activity: Extracellular Single-unit Recordings on the Maestro  Multielectrode Array