Assay Plates

Porvair Sciences have a range of clear polystyrene bottom, glass bottom and solid bottom assay plates that are specifically designed for absorbance, fluorescence, luminescence and scintillation applications. Porvair Krystal series clear bottom plates are now recognised as industry-leading tools for Pharma drug discovery and screening. Our standard clear polystyrene bottom plates have bases just 0.4mm thick and are moulded from highly polished tools to reduce flow lines, artefacts and scratches, guaranteeing good results with all types of bottom-reading instruments. For the more modern demanding confocal readers, Porvair Glass Bottom plates have been shown by leading research institutes to be unsurpassed for flatness, linearity and optical clarity. Our sparkling pure borosilicate glass is just 175µm thick with a flatness tolerance across the plate of +/- 15µm ensuring superb crisp images every time.

What are assay plates?

Assay plates are flat cell culture plates consisting of multiple ‘wells’ which can be used as small test tubes. This type of sterile microplate is considered a standard tool in both scientific research facilities and laboratories for clinical diagnostic tests. Commonly assay microplates are used to inspect enzyme-linked immunosorbent, which is at the core of most human and animal diagnostic testing currently performed.

What do you mean by assay?

The term assay is used to describe the process of testing a substance or an object to determine its components. It could also be used as a verb in reference to conducting said test or analysing the results. Fields such as chemistry and biology are where you’d most often encounter it.

Usually, an assay is performed to determine if a substance is present, and in what amounts. Running blood tests to determine the levels of a specific hormone, for instance, can be classified as an assay. Determining the potency of a drug is another type of testing that is considered an assay.

Plate-Based Assays

Plate-based assays are also commonly used in experimental biology when examining the state of a cell after it’s been subjected to manipulation or experimental treatment. Such crucial assays are performed in assay plates designed specifically to aid the physical, biological and chemical analysis of cell samples.

Employed in a variety of applications ranging from drug discovery and research to bioassay validation, manufacturing and quality control, plate-based assays are a popular tool in academic and research organisations as well as the fields of biotechnology and pharmaceuticals. The majority of plate-based assays are conducted using sterile cell culture microplates, including the popular 96 well assay plate and the versatile glass bottom assay plate.

What is ELISA (enzyme-linked immunosorbent assay)?

ELISA, also known as enzyme immunoassay (EIA), is a popular technique for plate-based assay used to detect substances such as hormones, proteins, antibodies, and peptides. This technique focuses on immobilising the antigen on a solid surface before it’s complexed with an enzyme-linked antibody.

Using a specialist ELISA plate, the conjugated enzyme activity is assessed via incubation with a substrate, producing a substance which can be used for detection. It’s incredibly important to use a sterile microplate during this detection to ensure that the highly specific antibody-antigen interaction goes off without interference.

96 well assay plates are the preferred cell culture plate used for ELISA thanks to their ability to passively bind proteins and antibodies, making this assay much easier to plan and perform. Over the course of the assay, researches can immobilise the reactants to the surface of the specialist ELISA plate and easily separate the bound material for the unbound substances.

How to get the most from your plate-based assays

For optimal research outcome, we advise you make sure you’ve selected the right assay and the best tools (e.g. assay plates) for the analysis. In fact, choosing assay microplates optimised for the reagents you will be using is key for obtaining quality data.

When it comes to selecting assay plates, you usually have a choice of clear, opaque and transparent. The most important thing to consider before choosing between the different glass bottom assay plate options is their reflective property. Do you need opaque assay plate walls to prevent well-to-well cross talk? We recommend opting for solid opaque plates if your assay involves scintillation, fluorescence and luminescence.


Black cell culture plates, on the other hand, are great for fluorescence assays. With less opaque surface to reflect the light, clear-bottom assay plates have lower luminescent signal intensity, but they are the go-to 96 well assay plate choice for absorbance assays.

Clear bottom plates are also useful if you wish to view the cells before the assay; however, we wouldn’t recommend these cell culture microplates if you are using a bottom-reading instrument, as the clear bottom may lead to increased levels of well-to-well cross talk. 

To avoid this issue when conducting an assay with clear glass bottom assay plates, we advise researchers to use top reading instruments whose detector can minimise the amount of light which leaks from the well by interfacing more closely with it.

If your assay involves UV wavelength measurement (e.g. nucleic acid quantitation), you can also get special UV-transparent microplates.

What is an assay in microbiology?

In microbiology, an assay can be performed exclusively on B vitamins. For instance, scientists can measure the growth rate of microorganisms which require vitamins by exposing them to an environment containing different foodstuff preparation quantities and unknown quantities of said vitamin.

What is an assay in biochemistry?

Meanwhile, an assay in biochemistry involves the in vitro analysis performed to detect, measure and examine the binding of a biological molecule (e.g. an enzyme) and the way it behaves. This type of analysis is exclusively performed in sterile microplates to ensure that no contaminants affect the readings.

What is the purpose of a protein assay? Why are protein assays important?

Another key application of assay plates in biological research and diagnostic testing is the analysis of proteins. The main purpose of a protein assay is to examine the protein content of a sample, determining its quantity and concentration. 

A protein assay can be done either as the first step of a larger research or as the final step of clinical testing conducted to detect and diagnose a disease. In some cases, a protein assay is performed to capture the compound in a sterile cell culture plate before it undergoes structural analysis.

Whatever the context of the protein assay, it’s an important step of any research. Knowing the concentration of proteins helps scientists to accurately label them prior to modification, and using the right assay microplates for the purpose helps ensure all the results are untampered with.

Microplate assays for high-throughput screening

Modern day high-throughput applications commonly use 96 well assay plates (8 x 12) as their preferred compound library screening format. Capable of measuring cell proliferation, binding interactions, enzyme activity and more, these assay plates are a favourite for a range of heterogeneous and homogeneous assays.

The assays which can be performed in our assay microplates vary from scintillation and immunoassays to highly sensitive luminescence and fluorescence-based assay which have been adapted to the microplate format more recently.

In addition to the technology currently available for conducting and analysing assays in 96 well assay plates, potential future developments include full screening automation and miniaturising assays in high density cell culture microplates.

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