A Full Plate: UV/Vis Microplate Readers

The Microtiter® plate--often referred to as the microwell plate or just simply the microplate. The origins of this plastic phenomenon go back to the Cold War era with some amazing innovations applied to this device along the way. Designed to take the burden off of the test tube and the petri dish, the microplate has served its purpose well and gone on to more sophisticated applications.Microplates come in a variety of shapes and sizes, although the establishment of some guidelines by the Society of Biomolecular Screening (SBS) has led to some standardization of the 96-well microplate: microplates measure 5.030" lengthwise and 3.365" across. For more information on the standardization of 96-well microplates, visit the following web site (www.miptec.com/standard.htm). From 6 wells to 1,536 wells, square to rounded wells, black plates to opaque plates, there is probably a microplate out there to suit your needs. The next question you might pose then is this: "Is there an instrument out there that can read my microplate?"Readers, washers, dispensers, incubators, shakers, robotic handlers--the list of microplate instrumentation continues to grow. As with microplates, microplate readers come in an array of shapes and specifications. Whether for photometric, luminometric, or fluorometric readings, instrumentation for microplates has followed the microplate down the road of progress. At this point, instrumentation may already be ahead of its time; while instrumentation is currently available for Greiner's 1536 Micro Assay Plate, the new Ultramark Microplate Reader from Bio-Rad Laboratories can handle 3,456-well microplates.Microplate applications are expanding at an alarming rate and are vital to numerous fields. From nucleic acid and protein quantitation to enzyme-linked immunosorbent assays (ELISAs) to kinetics assays, the tasks that microplates are put to are too numerous to list here. Regardless of what applications you use microplates for, there has to be a way to interpret what a microplate is telling you. In this issue, LabConsumer looks at UV/Visible-capable microplate readers, denoting readers capable of measuring down into the UV spectrum (from 190 to 380 nm). We will also provide information on companies that manufacture non-UV-capable instrumentation and automated microplate washers.Why UV? The step down into the ultraviolet range is an important one, as many of today's applications require measurements in this spectrum, including 260/280 nm nucleic acid quantitation, lipoprotein measurements, and so on. The growth of applications in this spectrum has led manufacturers to provide instrumentation capable of detecting in this range. It could be argued that ultraviolet detection is more important to those using spectrophotometers, but LabConsumer opted to discuss microplate luminometers and fluorometers, as well.The instruments listed in this article span a wide range of features and functions (and prices). The final purchasing decision will ultimately be based on a number of considerations. The following is a brief outline of some of the ways microplate readers differ. For any type of instrumentation, one of the most significant considerations should be if you want a stand-alone or a PC-based instrument. Many instruments are now PC-based, while others offer onboard software and different measurement and analysis capabilities, such as endpoint analysis, kinetics, curve fitting, and so on.Wavelength range should be a primary consideration (especially for those using spectrophotometers), along with accuracy and resolution. For those in high-throughput labs, a speedy instrument may save countless hours of waiting. The list of available options for instrumentation is usually extensive: barcode options, robotic options, software options, plate shaking, incubation--the list goes on. Many luminometers offer single or multiple injection capabilities. And lastly, some instruments play multiple roles in laboratories, offering both fluorescence and absorbance measurements, such as Bio-Tek's FL600, Molecular Dynamics' BioLumin 960, Perkin-Elmer's HTS 7000 Plus, Tecan's SpectraFluor, EG&G Wallac's 1420 Victor2 (which combines a time-resolved fluorometer, photometer, and luminometer), and SFRI's alpha 4 LS (which reads optical density and luminescence).Two companies not listed in the table that offer microplate luminometers not extending into the UV range are Bioscan Inc. (800-255-7226 or www.bioscan.com) and Zylux Corporation(888-522-5487 or www.zylux.com). Bioscan (Washington, D.C.) offers the Lumi-96 microplate luminometer, which can read one microplate in 60 seconds. This instrument runs on Windows™ software. New from Zylux (Boca Raton, Fla.) is the Windows™ 95-based Microplate Luminometer. This instrument is useful for all "glow" applications, such as reporter gene assays, immunoassays, and PCR quantification, to name but a few.Lastly, the MicroReader 4 from Hyperion (Miami, Fla.) is a self-contained microplate reader with a wavelength range extending from 405 nm to 650 nm. The MicroReader 4 features a built-in 486 computer, floppy disk drive, and microplate shaker and can read a 96-well microplate bichromatically in less than 20 seconds. For more information contact Hyperion (800-332-2849 or www.hyperionclinical.com).The author can be reached online at sbeck@the-scientist.com.Awareness Technology Stat Fax 2100Rosys Anthos ht3Bio-Tek FL600EG & G Wallac Victor2Instruments S.A. FluoroMax-2Labsystems Multiskan AscentMolecular Devices SpectraMax PlusPackard Instruments FluoroCountRosys Anthos ht2Molecular Dynamics BioLumin 960PerSeptive Biosystems CytoFluorTecan SpectroFluorTropix TR717

A Full Plate: UV/Vis Microplate Readers

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