Microplate Reader Madness

Courtesy of Cellomics The ArrayScan VTI HCS Reader Microtiter plates have become standard consumables in both research and clinical laboratories. Also known as microwells and microplates, microtiter plates essentially are flat trays bearing a number of isolated reaction chambers, from six to 1,536, and arranged in a 3n x 2n array (e.g., for a 96-well plate, n=4). All the plates share a common footprint (approximately 128 x 86 mm) regardless of manufacturer and configuration, so that robots, plate readers, and automated liquid handlers can easily accommodate new applications, everything from nucleic acid and protein quantification to ion-uptake analysis. To cull data from these reactions, specialized microplate readers can use photomultiplier tubes, photodiode arrays, or charge-coupled devices (CCDs) to detect metrics such as absorption or emission, fluorescence, and luminescence. In recent years, manufacturers have even combined reading methods to build multimode instruments that increase versatility and throughput. According to a 2002 report by PhorTech International of San Carlos, Calif., the US microplate reader and equipment market grew from $83.1 million (US) in 1999 to an estimated $121 million in 2002. Dedicated absorbance readers account for roughly half the units purchased since 1999, while multimode instruments comprise about one-third. Overall, Molecular Devices of Sunnyvale, Calif., controls approximately 32% of the marketplace, but runner-up PerkinElmer Life and Analytical Sciences of Boston is coming on strong. Bio-Tek Instruments of Winooski, Vt., Bio-Rad Laboratories of Hercules, Calif., and Thermo Labsystems of Vantaa, Finland, round out the top five positions. MULTIMODE MENAGERIE PerkinElmer recently expanded its microplate reader series with the new Victor3™ family of instruments. The basic Victor3 instrument is already a multimode master for fluorometry and luminescence; its fully-loaded cousin, the Victor3 V, can screen a wide range of microplates, from six to 1,536 wells, for ultraviolet absorbance, luminescence, and fluorescence, among others. "In research, you never quite know exactly what application you might need for any given experiment," explains Paul Gillyon, vice president and general manager of biopharmaceutical. "So it's always valuable to have that kind of [multimode] flexibility, especially in labs where work may vary from day to day." All Victor3 readers use two light sources: a continuous tungsten halogen lamp for photometric and fluorometric detection between 340 nm and 800 nm, and an ultraviolet xenon flash lamp for time-resolved fluorescence and ultraviolet absorbance measurements. Victor3 improves on its Victor2™ predecessor with improved optics for luminescence detection and the added UV capability, says Gillyon. The unit also contains software to comply with the US Food and Drug Administration's Rule 21 CFR Part 11 (21 CFR 11) for paperless record-keeping. It can be outfitted with stackers to run either 20 or 40 microplates for higher throughput and walk-away operation. Courtesy of Tecan US The Tecan GENios Pro modular multifunction microplate reader Zurich-based Tecan's new GENios™ Pro and its updated version of Magellan software also comply with 21 CFR 11. Targeted for drug discovery, genomics, and proteomics applications, the GENios Pro can detect absorbance, luminescence, and fluorescence for microplates containing from six to 384 wells. GENios instruments screen a traditional 96-well microplate in about 30 seconds. For fast kinetic studies, such as dual-reporter gene assays, the system can accommodate up to three simultaneous reagent injectors for 96- and 384-well plates. "We measure in the nanosecond range, so we can determine the lifetime of reactions such as fluorescence over four nanoseconds," explains Melissa Foshee, associate product manager for detection and separation systems for Tecan US. Product developers, she adds, have focused on increasing the versatility and modular nature of Tecan readers while keeping size and cost down. GENios Pro can be matched with Tecan's Connect microplate stacker system for automated screening. The stackers come in 30- or 50-plate varieties, and the entire reader-stacker system sits on the robotic deck of Tecan systems such as the Freedom EVO™. "You can automate an entire ELISA assay or a wide range of cell-based assays depending on the research needed," Foshee says. Relative newcomer Carl Zeiss MicroImaging, of Thornwood, NY, has released a pair of instruments aimed at researchers with increasingly high-throughput needs. Both are based on the plate::vision reader developed by Zeiss MicroImaging parent Carl Zeiss, of Jena, Germany. Zeiss product designers focused a xenon light beam into individual wells simultaneously using a "mini-lens array" of 96 tiny, well-sized lenses. "They focus the xenon light into a relatively small spot in the well, increasing the reader's performance," says Peter Baurschmidt, market manager for Carl Zeiss' molecular medicine department. "The trick is that each of these 96 lenses has to be aligned carefully, and that's not something trivial." A plate mover gently slides larger microplates with 384 or 1,536 wells over the mini-lens array to ensure complete area scans. Zeiss MicroImaging's new readers, the multimode plate::screen and the ultrahigh-throughput plate::explorer, are automated versions of plate::vision. The multimode version is optimized for 1,536-well plates but can accommodate 96- and 384-well formats as well, organizing them in stacks of up to 286 standard or 220 lidded plates for cell-based assay studies. Designed to screen more than 50,000 wells per hour in any detection mode, plate::screen can scan a 96-well plate in one second flat. Plate::explorer goes even further by integrating liquid handling, centrifugation, and sample-storing robotics into a cohesive system. Bio-Rad Laboratories has its own multipurpose plate-reading system, the Lumimark, for benchtop research. As its name suggests, the instrument handles all types of luminescence studies as well as standard absorbance assays. Lumimark's single photomultiplier tube setup is ideal for long-glow luminescence scans; its customizable lag time feature is useful in kinetics or low-background studies. One or two injectors can be added to the system for flash-luminescence scans. The system reads only standard 96-well microplates, however, unlike Bio-Rad's Ultramark, a higher throughput absorbance-only detector that accepts up to 1,536-well plates. The new PHERAstar multimode device from BMG Labtechnologies of Offenburg, Germany, can detect fluorescence intensity and polarization, time-resolved fluorescence, and luminescence for plates containing as many as 1,536 wells. A FEW MINOR TWEAKS Some reader manufacturers have boosted the versatility of their instruments by enhancing existing devices or adding applications. Bio-Tek Instruments updated its high-throughput Synergy™ HT microplate reader by incorporating reagent injectors in its newest version. "It's nothing much," says product manager Xavier Amouretti, adding that the upgrade opens Synergy HT up to flash fluorescence, for ion-uptake assays for example, and flash luminescence studies such as ATP determinations. "For those studies, reactions occur within a few seconds, and until now we didn't have the injectors for our readers to track them." Courtesy of Perkin Elmer Perkin Elmer's Victor3 V microplate reader Synergy HT readers scan microplates that have between six and 386 wells, requiring up to 35 seconds to read fluorescence of a 96-well plate or 15 seconds for absorbance. Read times depend on settings, though, with a wavelength range of 200 nm to 999 nm for absorbance and less for fluorescence. Ebersberg, Germany-based MWG Biotech's new multimode reader, the Sirius HT Injector, improves on its predecessors with three reagent injector positions, two on top and one on the bottom, "We ... had limitations on the applications side when it came to slow kinetics and flash-fluorescent measurements," explains Holger Eggert, product manager of microplate instruments. "We were basically just missing the injectors." Other than the new injectors, the new MWG reader differs little from existing Sirius HT instruments. The reader uses a halogen lamp and dual optics for visible and ultraviolet scans of microplates containing six to 384 wells. Software enhancements allowed Pittsburgh, Pa.-based Cellomics to broaden the applications of its two dedicated fluorescence readers for high-content screening, the ArrayScan HCS and KineticScan HCS. The new software modules include: Cell Health Profiling to follow individual events within cell lifetimes; Kinetic Molecular Translocation for studies within a sample cell; and Morphology Explorer that allows researchers to measure the size, shape, and other details of single-cell or multicellular structures. All are completely compatible with existing versions of the ArrayScan and KineticScan systems, according to Cellomics product managers. "The new bioapplications for our two platforms are really based on years of customer input into what types of features were needed," says Sarah Tencza, product manager for bioapplications. The automated morphology feature in particular is a push forward for Cellomics, she adds, since morphology studies are still widely done by hand by researchers snapping images of samples with fluorescence microscopes. In addition to enhancing applications, Cellomics has released the ArrayScan VTI, an automated fluorescence reader for large-scale biology and drug-discovery research. ArrayScan VTI, like other Cellomics microplate readers, uses a high-content screening device for cell-based studies. It employs a mercury-xenon arc lamp for fluorescent dye excitation and a high-resolution digital camera to image the reactions. "There are certain enhancements with ArrayScan VTI over our other reader models," explains instrumentation manager Martin Pietila. "For instance, we now have a very high three-dimensional resolution of cell targets." The ArrayScan VTI is capable of both three-dimensional and two-dimensional cell-assay studies, depending on researcher needs. Instead of screening microplates quickly for one data point per well, ArrayScan VTI picks up 200, although the increase affects the reader's speed. The instrument is capable of screening one 96-well plate every five minutes at its top speed, instead of under a minute like other readers. To bolster throughput, the screening system's stacker can hold up to 80 microplates in either 96- or 384-well formats. Applied Biosystems (ABI) of Foster City, Calif., still offers a pair of fluorescence- dedicated instruments. The CytoFluor 4000 Multi-Well Plate Reader can scan both tops and bottoms of microplates with between six and 384 wells. Optional stacking accessories allow robotic operations of as many as 80 plates at a time. A temperature control model keeps microplate environments stable to within +/- 0.3°C. ABI takes a confocal approach with its 8200 Cellular Detection System, a macroconfocal imaging instrument that detects emissions during binding events of live cells or beads. A 633-nm red laser excites fluorescence in sample material, which is then recorded by a pair of photomultiplier tubes. The 8200 can run 96-, 384-, and 1,536-well plates, with a total throughout of about 30,000 well-reads per 18-hour day. GOING BEYOND MICROPLATES Some manufacturers have added multiple modes to their instruments, with readers that can sift through cuvettes, microarray slides, PCR tube trays, and Terasaki trays. Bio-Tek's new FLx800Ti fluorescence reader, for example, handles low-profile PCR tubes and microplates for nucleic acid hybridization or incubated kinetic assays. Courtesy of Beckman Coulter The LD 400 Luminescence Detector Matt Maloney, product manager of detectors for Beckman Coulter in Fullerton, Calif., says developers there are hard at work on an absorbance microplate reader, dubbed AD 200, for cuvettes as well as microplates. (The company's existing AD 340 absorbance detector reads microplates only.) The monochromatic reader, due out sometime in 2004, should handle standard 384-well plates and offer a flexible range of wavelengths for quick concentration and sample-purity studies, according to Maloney. Thermo Labsystems, part of Waltham, Mass.-based Thermo Electron, released the Multiskan® Spectrum microplate and cuvette reader this summer. The monochromatic spectrophotometer is built to screen microplates containing six to 384 wells for absorbance across visible and ultraviolet wavelengths (200 nm to 1,000 nm). The dual-beam cuvette reader includes sample and reference beams meant to enhance sample stability. Molecular Devices of Sunnyvale, Calif., has added multimode and multiplatform reading in its recently released SpectraMax® M2. "The new instrument has absorbance reading and fluorescence capability for both the microplates and cuvettes," explains Stephen Oldfield, vice president of worldwide marketing. The M2 reader also is capable of time-resolved fluorescence and luminescence measurements; its PathCheck™ sensor automatically measures the depth of samples, normalizing its measurements to cuvette standards. "It's like having 384 cuvette readings in one run," Oldfield says. The SpectraMax M2 passes light from a xenon lamp through a pair of monochromators to measure absorbance or fluorescence and detect emissions with photomultiplier tubes. Scan times are less than 20 seconds for single 96-well plates, and up to 45 seconds for 384-well plates. Washington, DC-based Bioscan has equipped its new Chameleon multimode microplate reader for liquid scintillation counting of radioisotope-tagged samples. The multimode instrument is Bioscan's only microplate reader. It can conduct radiometric measurements of cell proliferation or radioimmunoassays, as well as fluorescence detection of enzyme assays, luminescence monitoring of immunoassays, and nucleic acid and protein quantification. Chameleon's developers say they sacrificed high throughput for versatility. "It's not meant to sit there all day long and run plate after plate," says Victor Tchiprout, sales and marketing manager. "Our goal is to be very flexible for the needs of university research laboratories." The instrument takes about 90 seconds to read 24-, 96-, and 384-well microplates. A xenon flash lamp provides illumination, and a single photomultiplier tube and photodiode detect wavelengths from 230 nm to 670 nm. Researchers hoping to catch the swift reactions of flash luminescence can use available injectors, Tchiprout says. Bioscan product designers are currently looking into stacker solutions to increase Chameleon's robotic potential. Alpha Innotech of San Leandro, Calif., has equipped its AlphaArray™ microarray imager, an instrument primarily used for gene expression, to accept standard microplate sizes as well. The instrument uses a broadband metal halide lamp for illumination and a CCD camera to record data. The system is useful for researchers who want to study in more detail the expression of a few genes isolated during a microarray scan, explains Greg Fisher, senior product manager for array imaging products. AlphaArray's instruments are not robot-friendly and currently read microplates upside down, making them useful for dry or sealed-well experiments only. "A lot of DNA and protein arrays include wet preparation steps, but the sample can be dried before it is imaged," says Fisher. "Our plans for the next-generation reader are to make [the AlphaArray] robotic and capable of wet chemistry." Tariq Malik (tariqjmalik@hotmail.com) is a freelance writer in New York City. function sendData() { document.frm.pathName.value = location.pathname; result = false if (document.frm.score[0].checked) result = true; if (document.frm.score[1].checked) result = true; if (document.frm.score[2].checked) result = true; if (document.frm.score[3].checked) result = true; if (document.frm.score[4].checked) result = true; if (!result) alert("Please select") return result; } .myradio{background-color : #94bee5} Please indicate on a 1 - 5 scale how strongly you would recommend this article to your colleagues? Not recommended 1 2 3 4 5 Highly recommended Please register your vote

Microplate Reader Madness

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