Editorial Article
Friday October 02, 2009
by Caitlin Smith
The performance of a microplate reader will depend in part on what you want to do with it. They can be adapted to fit your needs within limits, but some offer different features than others.
“The combination of speed, sensitivity, multi-detection capability, and robotic integration, certainly are the key challenges in developing a microplate reader,” says E.J. Dell, business and applications development scientist at BMG Labtech. “Big pharma [focuses] on easy-to-use reliable readers with robust performance, while academic laboratories like a great deal of flexibility and lower cost.” A range of features and configurations resulted from this range of demands, and both are still changing.
The development of readers goes hand in hand with that of biochemical assays, too, notes Dell. “A collaborative effort of kit and reader manufacturer is of utmost importance to foster assay development and screening in microplate-based formats,” he says. “Cost and efficiency lead to the development of multiplexed assays, giving the opportunity to screen for more than one biochemical target in a single run.” Here’s a look at some of the features currently available.
Modularity to fit the bill
When a wide range of features is available, it is helpful to be able to choose only the features you need, avoiding the potential complications—and expense—of unnecessary instrumentation. BioTek offers this choice to researchers with their Synergy™ Multi-Mode Reader family, which includes their Synergy 4 with Hybrid Technology. “Synergy 4 is the first, in a new class of multi-mode readers, incorporating both monochromator and filter-based fluorescence detection systems in one compact instrument,” says Peter Banks, scientific director at BioTek. For all Synergy instruments, you can select only the modules you need, with the option to add more later.
Xavier Amouretti, product manager at BioTek, notes the challenge of creating one microplate reader that can accommodate the increasing number of new assays. “When purchasing a plate reader, scientists need an instrument that is both very sensitive and extremely flexible—traits that are often antagonistic when developing a new instrument, and usually result in compromise,” says Amouretti. “This is why BioTek created the Hybrid category of plate readers with the Synergy 4—combining optical systems usually found on separate instruments to increase the application range while retaining high performance normally found only in specialized readers.” BioTek is aiming further, according to Amouretti, who says they will introduce a reader at the end of the year covering “the entire range of microplate-based fluorescent, absorbance and luminescence assays.”
Tecan also offers modularity, as well as a specialized reader plate that enables small volume samples (BioTek’s is the Take3 Multi-Volume Plate). Gerald Probst, marketing product manager at Tecan, sees a “clear trend in low sample volume combined with increased sensitivity and multifunctionality of the detection device.” Tecan’s Infinite M200 NanoQuant reader, “together with the NanoQuant plate, is the ideal microplate reader for a broad range of applications for nucleic acid measurements like DNA- or RNA-quantification, for quality control and labeling efficiency,” says Probst. The Infinite M200 NanoQuant reader uses Tecan's Quad4 Monochromators technology, which optimizes stray light rejection and obviates the need for filters.
Stretching instrument limits
Increasingly, scientists want to use microplate readers for cell-based assays, which Amouretti says is challenging for the instrument. “Fluorescent or luminescent cellular assays usually require very high performance because of their low signal-to-background ratios,” says Amouretti. “They also require specialized features such as tight temperature control, plate shaking or multiplexed detection technologies. This forces manufacturers to get a new perspective on the development of instruments that were originally mostly designed for simple biochemical assays.”
Such developments are occurring in response to demand. BMG Labtech’s new PHERAstar FS is a high-throughput screening microplate reader that, as a spectrometer, detects the entire ultraviolet-visible spectrum. Two features have been added for use with new high-throughput cell-based screening assays, such as Invitrogen’s GeneBLAzer® and LanthaScreen® assays. One is “reagent injectors for precise kinetic measurements that inject at the point of measurement, [allowing you to] obtain 50 readings per second while the injection is occurring in 384-well plates,” says Dell. The other is direct-optic bottom reading with high-resolution cell layer scanning, which gives higher signal-to-noise ratios from GFP and GeneBLAzer® assays, says Dell: “No need to manually change filters or dichroic mirrors as with other systems—the high-performance optic modules of the PHERAstar FS can be used for both top and bottom reading.”
Whether your experiments demand a simple readout of absorbance measurements, or high-throughput cell-based screening assays, careful consideration will surely help you find a microplate reader to suit your lab.