There are some variations in plate coating protocols but they typically involve the following steps:
- Add coating solution (e.g. antibody or antigen)
- Overnight incubation, normally at room temperature
- Aspirate (removal of coating solution)
- Wash 3 times with washing buffer (step not mandatory for all coatings)
- Dispense blocking solution
- Incubate, typically 1-3 hrs.
- Aspirate (removal of blocking solution). Residual volume is critical in this step!
At the most basic level a multichannel pipette is enough to coat a single plate. However, ELISA coating is typically applied to many plates at a time and is normally a production process. Therefore, automation is highly desired.
Plate coating is a demanding process and most demands come from the fact that it is a production process involving the preparation of many plates per day. The most important demands are:
- Throughput: Can range from a few dozen plates per day for homebrew ELISA assays to hundreds or even thousands of plates per day for kit manufacturers. To achieve this throughput a very fast is required.
- Reliable handling of troublesome ingredients: the reagents used in plate coating can be troublesome as they may clog the thin needles typically found in microplate washers (for example, buffers containing high salt or sugar concentrations) or produce large amounts of foam (for example, detergent-containing wash buffers or protein solutions).
- Low residual volume: this is of utmost importance when removing the blocking reagent as any residues would interfere with the actual assay and the washing steps in the plates.
- Easy setup: time is gold when processing large quantities of plates. Therefore, it is important to start your daily work as soon as possible.
- Easy maintenance: it is important to keep to perform regular maintenance.
Thesatisfies all plate coating demands:
- High throughput thanks to its integrated stacker with a single-rail design: it can coat or block up to 250 plates/hour and wash (3x) up to 150 plates/hour.
- Clogging is prevented thanks to the large diameter of its dispense and aspirate needles.
- Foaming is prevented thanks to the ability to optimize dispense position and speed by continuously adding an anti-foaming reagent to the liquid waste trap.
- Lowest residual volumes thanks to 3D-positioning of the aspiration needles and its powerful vacuum system with a constant and stable flow rate.
- Daily setup and shutdown normally involves only running the integrated rinse and cleaning routines. The waste management is extremely simplified thanks to its self-emptying waste trap with the automated addition of sterilization reagent, if necessary.