In the 1950s, a Hungarian physician, Gyola Takatsy, needed a faster way to test patients for influenza, and that spawned microplates. The first ones consisted of 100 wells that were milled one by one. Eventually, microplates became the new test tube—one of the most commonplace things in life science labs.
Still, scientists must consider which microplates to use. The complexity of present-day microplates is exemplified by the fact that the Thermo Fisher Scientific (Waltham, MA) microplate website lists 922 items. If that number makes it difficult to imagine where someone might start trying to decide what product to purchase, take a look at the company’s “Guide to Microplate Formats and Well Designs” to consider the various formats, well shapes, and even colors.
To provide some perspective on microplates, Trevor McFarland, laboratory operations manager at the Oregon Health and Science University Integrated Genomics Laboratory in Portland, made time to answer a few questions.
Most life scientists use some sort of microplate, and probably for more than one application. McFarland, for example, uses microplates for many processes: amplification protocols related to gene expression, genotyping, or methylation microarray projects; Sanger sequencing; fluorescent-based nucleic acid quantification; and qPCR and nucleic acid concentration normalization. That gives McFarland a good perspective on which plates work for which applications. “Plate selection is specific to the application needed,” he says.
Take fluorescent assays, for example. Here, McFarland explains that “the plates must be black to avoid signal bleed over to an adjacent well.” McFarland and his colleagues often run DNA-quantification assays that use a fluorescent dye, PicoGreen®. For this assay, the scientists include an epMotion liquid-handling robot from Eppendorf (Hamburg, Germany) to automate the process. “The robot pipettes samples, controls, and standards from either a dilution plate—a 96-well microplate—or tubes into a black CoStar Plate—96 wells—that can then be read in a fluorescent microplate reader,” McFarland explains. “This allows us to assay up to 88 samples, including standards curve and control samples, in a single run.”
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Other applications need just the opposite. “In the case of a qPCR plate, there is a requirement that the plate be optically clear in order for the signal to be read by the qPCR instrument,” McFarland explains.
In other cases, key features are the volume of the wells in a microplate and the labware’s overall size. For microplates that will be used in PCR amplification, for instance, McFarland says the labware must fit the thermocycler being used and have a format compatible with the volumes required. Sometimes the volume of the wells themselves makes up the key constraint. As an example, McFarland says, “In some cases, we use MIDI deep-well plates to accommodate the high volumes needed for precipitation, etc.”
Luckily, today’s scientists don’t need to go to a milling machine to churn out microplates. Instead, a quick search through online catalogs provides more options than a scientist could create in a career. The bigger challenge is finding the right microplate for the job, but it takes only a little reading to get it right.
For additional resources on microplate technology, including useful articles and a list of manufacturers, visit www.labmanager.com/microplate-technology