Microplates Knowledge Base
- Microplate selection by detection method
- Plate dimensions, photos, and working volumes
- Plate treatments and coatings
- Table of all microplate products
- The edge effect
- Plate seals
- Video tutorials
- Custom plate services at PerkinElmer
Assays that can be run in a microplate format generally benefit from the ability to use relatively low volumes of reagents in a single assay, the ability to scale assay volume as desired, and the ability to increase "throughput" (the number of assays that can be run at one time). A variety of microplates are available for a wide range of applications. The correct selection of a microplate can improve assay performance in a number of ways. In addition to the information found on these pages, you can refer to our Online Microplate Selector Tool for help selecting a microplate for your particular assay or application.
Microplate Selection by Detection Method
- Includes plates used for colorimetric ELISAs, ELAST ELISA, assays that use chromogenic substrates such as BCIP, DAB, 4CN, and Fast Red, and other absorbance and colorimetric assays.
- Includes plates used for fluorescence intensity assays, fluorescence polarization assays, fluorescent calcium flux assays, TRF assays (time-resolved fluorescence, including DELFIA®), and TR-FRET assays (time-resolved Förster resonance energy transfer assays, including LANCE®).
- Includes plates used for Alpha assays (AlphaScreen® and AlphaLISA®), ATPlite® assays, britelite™ assays, steadylite® assays, neolite™ assays, other luciferase-based assays, AequoScreen® assays, PhotoScreen™ assays, luminescent calcium flux assays, chemiluminescent ELISAs, assays that utilize luminol or luciferin substrates, and other luminescent technologies.
- Includes plates used for microscopic visualization, cellular imaging, live cell imaging, and high content screening.
- Includes plates used for radioligand binding assays, HPLC Fraction Analysis, radiochemical filtration assays, liquid scintillation counting assays, 3H-thymidine assays, SPA assays, FlashPlate® assays, and Cytostar-T™ assays.
- Includes plates used for compound storage, preparation of working solutions, and solution transfer.
Plate dimensions, photos, and working volumes
Click here for more information on plate dimensions, photos, and recommended assay volumes.
Plate treatments and coatings
Click here for more information on various plate treatments/coatings and their intended purposes, including high-bind and low-bind plates, PDL-coated, collagen-coated, WGA-coated, and other pre-coated or treated plates.
Table of microplates
View our table of microplates by application.
Well-to-well cross-talk occurs when a portion of the signal generated by a sample contained in a well of a microplate is also detected in an adjacent well, and thereby contributes a non-specific amount of signal in the adjacent well. Assays that produce high signal levels are more prone to cross-talk. For example, chemiluminescent assays can generate relatively high signals leading to significant cross-talk. Also, the wavelength of the light emitted is a factor, since the shorter the wavelength of the emission is, the higher the energy level is, and the more cross-talk may be observed.
Cross-talk can be caused by factors related to either the plate reader used to read the plate, or by the microplate itself.
Cross-talk can result from misalignment of components of the optical detection pathway of the plate reader in relation to the microplate, so that a portion of the signal from an adjacent well is collected at the same time as a well being measured. Some instruments use apertures or other physical masking devices to isolate the well being measured from adjacent wells. Misalignment or poor masking using these systems can also lead to cross-talk.
Various factors related to the specific microplate being used can lead to cross-talk. The signal from one well can be transmitted through the sides of the well into adjacent walls. Light piping, which is the lateral transmission of light, can occur through the bottom of the plate, or through clear top seals on the top of the plate.
The important plate design parameters that impact the magnitude of the cross-talk include:
- Transparency of the microplate plastic
- Clear plastic microplates can have the highest cross-talk
- Black plastic microplates give the lowest amount of cross-talk
- White plastic microplates give medium cross-talk; the magnitude of the cross-talk varies with the concentration of titanium dioxide used as whitener
- Light-grey microplates have lower cross-talk than white plates
- Design of the plate
- Wall thickness of adjacent wells
- Thickness of the bottom
- Distance from well-to-well
- Well geometry
The Edge Effect
The term “edge effect” in microplate-formatted assays refers to the observation that the results measured from the wells on the edge of the plate may often at times be statistically different from wells towards the center of the plate. The values obtained from the edge wells may be either high or lower than those towards the center.
Edge effects can occur in both biochemical and cell-based assays. Edge effects can be caused by multiple factors, which may be difficult to identify and correct. Some laboratories routinely leave the edge wells empty, although this avoids the problem rather than solving it. In screening laboratories that need to process a large number of samples, leaving the edge wells empty may not be a practical option.
Although there have not been any systematic studies highlighting the causes of edge effects, some general observations have been reported in the literature:
- Thermal gradients across the plate during incubation times may lead to edge effects if the development of the assay signal is temperature sensitive. This is of particular concern if the plate is subjected to different temperature environments during the assay, such as moving the plate in and out of a 37 oC incubator, since the edges of the plate will heat or cool at a different rate from the center.
- The evaporation rate of liquid in the wells may be different on the edges compared to the rest of the plate. For cell-based assays where the plate is placed in a 37 oC 5% CO2 incubator, the culture medium may evaporate more rapidly from the edge wells than center wells. Also, if the plate is covered with a lid during the incubation, gas exchange across the plate may not be uniform. This can lead to differences in salt concentrations or pH in edge wells, which can affect cell attachment or cell metabolism.
- Edge effects may be more pronounced as the plate well-density increases from 96- to 1536-well, since evaporation may be more of an issue as the well volume deceases.
- Edge effects may be reduced in cell-based assays by allowing the plate to pre-incubate for 1 hour at ambient temperature prior to placing it in a 37 oC incubator, since this leads to a more even distribution of cells on the bottom of the edge wells.1
We recommend several actions that may be taken to reduce or minimize edge effects:
- Carefully assess the assay workflow and laboratory environment to minimize any temperature gradients or other environmental factors that may differentially affect areas the plate.
- Consider covering the plate during incubations to prevent evaporation. Plastic lids that allow gas exchange are recommended for covering plates when performing cell-based assays. For biochemical assays that do not involve live cells, plates can be sealed with our TopSeal™ transparent sealing tape.
- Use incubators with adjustable humidity. At a high Relative Humidity (close to 100% RH) the evaporation will be minimal.
1. Lundholt, B.K., Scudder, K.M., Pagliaro, L. A Simple Technique for Reducing Edge Effect in Cell-Based Assays. J Biomol Screen 8, 566 (2003).
PerkinElmer offers a variety of plate seals. TopSeal™ is a range of plate seals that are applied to the top surface of the plate, and are used to prevent evaporation or radioactive contamination during assay incubation steps and/or plate reading measurements. TopSeal-A can be left on the plate during luminescent, AlphaScreen®, AlphaLISA®, and radiometric measurements. TopSeal plate seals have spectral properties that may interfere with other types of assay measurements (absorbance assays, colorimetric assays, fluorescence assays). For these types of assays, you should compare the plate measurement with and without a TopSeal plate seal to test for interference. BackSeal plate seals are plate seals that are applied to the bottom of the plate. BackSeal plate seals can be used to seal the bottom of a filter plate prior to the addition of scintillation cocktail, preventing leakage. BackSeal plate seals can also be used to change a clear-bottom plate into a white- or black-bottom plate in order to reduce cross-talk during top-reading measurements.
Plate Seal Products
|Product||Type of Seal||Plate Format||Number of Seals||Catalog Number|
|TopSeal-A||Clear adhesive seal||Any||100||6050185|
|TopSeal-P||Heat seal for Barex® plates||(all)||100||6005160|
|TopSeal-S||Heat seal for polystyrene plates||(all)||100||6050192|
|BackSeal||White adhesive seal||(all)||55||6005199|
|Black adhesive seal||(all)||55||6005189|
Custom Plate Services at PerkinElmer
PerkinElmer offers custom microplate services, including bulk ordering, fast and flexible plate barcoding, biological plate coating (including poly-D-lysine, collagen, streptavidin coating, antibody coating, and other coatings on request), custom tissue culture-treatment, custom high protein binding treatment, custom sterilization of microplates, special packaging, and other microplate treatments. If you are interested in custom plate services, please contact our custom service team: