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Microplates Knowledge Base

Overview


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.

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Microplate Selection by Detection Method


Absorbance/Colorimetric

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.

Fluorescence

Includes plates used for fluorescence assays such as:

  • Fluorescence intensity assays
  • Fluorescence polarization assays
  • Fluorescence calcium flux assays
  • TRF (time-resolved fluorescence) assays including DELFIA®
  • TR-FRET assays including HTRF® and LANCE® Ultra™

Luminescence

Includes plates used for luminescence assays such as:

  • Alpha assays including AlphaLISA®, AlphaScreen®, AlphaLISA® SureFire® Ultra™
  • Reporter gene assays including britelite™ plus, neolite™, steadylite™, sensilite™, twinlite™
  • Cytotoxicity and cell proliferation assays including ATPlite™, ATPlite™ 1step, ATPlite™ 3D, ATPlite 1step™ 3D
  • Other luciferase-based assays including AequoScreen® and PhotoScreen® assays
  • Luminescent calcium flux assays
  • Chemiluminescent ELISAs

Assays that utilize luminol or luciferin substrates

Next Generation Sequencing

Includes plates and consumables needed to run sample preparation workflows, which has been engineering specifically for NGS applications.

High Content Screening

Includes plates used for microscopic visualization, cellular imaging, live cell imaging, and high content screening.

Radiometric

Includes plates used for radioligand binding assays, radiochemical filtration assays, liquid scintillation counting assays, 3H-thymidine assays, SPA assays, FlashPlate® assays, and Cytostar-T™ assays.

Storage

Includes plates used for compound storage, preparation of working solutions, and solution transfer.


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Plate dimensions, photos, and working volumes


Click here for more information on plate dimensions, photos, and recommended assay volumes.

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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.

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Table of microplates


We offer a variety of microplates for a wide range of applications. View our table of microplates by application.

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Cross-talk


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.

Instrument-related Cross-talk
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.

Microplate-related 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

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The Edge Effect


In microplate-formatted assays, the term “edge effect” refers to the observation that the measurement obtained from wells on the edge of the plate are often 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°C 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°C 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°C 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).

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Plate Seals


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 luminescence, AlphaScreen®, AlphaLISA®, AlphaLISA®SureFire®  Ultra, 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

ProductType of SealPlate FormatNumber of SealsCatalog Number
TopSeal-A Clear adhesive sealAll100

6050185

 

Clear adhensive seal, for 24-well plates24-well100

6005189

 

Black adhesive seal

All

100

6050173

TopSeal-BAdhensive seal for PCR platesAll100

6050174

TopSeal-SHeat seal for polystyrene plates 96-well100 6050192

 

BackSeal White adhesive seal96-, 384-well556005199

 

Black adhesive seal96-, 384-well556005189

 


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Custom Plate Services at PerkinElmer


PerkinElmer offers custom microplates services, including:

  • Bulk ordering
  • Fast and flexible plate barcoding
  • Biological plate coating including – poly-D-lysin, collagen, streptavidin, and antibody coating
  • Custom treatments including – tissue-culture, high protein binding and low protein binding
  • Customer sterilization

PerkinElmer also offers special packing and other microplate coatings and treatments. If you are interested in custom plate services, please contact our custom service teams:OnPointSM Custom Microplates Services

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