The BMG FLUOstar Galaxy, now sold as the FLUORstar OPTIMA, is a microplate reader with extreme flexibility. The lab I work in has three of these plate readers, a consequence of being extremely happy with the first one we purchased as well as compatibility issues. The plate readers use xenon flash lamps for excitation and liquid filled fiber optics for light transmission and PMT detection. Although we predominantly use our plate readers for fluorescence, they can also be used for absorbance or luminescence based assays. These different modes are accessed essentially by changing fiber optics for a particular readout, along with changes in software settings. In addition to the different modes of data acquisition, up to two solutions can be added during assays, multiple wavelengths (selected by filters) can be considered in a single assay, plates can be shaken to aid mixing and temperature can be controlled.
The plate reader is controlled by easy to use software that needs to be installed on a PC (running at least Windows 95 with 64 Mbytes RAM and one serial port). The software provides a simple interface to the plate reader with clearly labeled icons accessing different features. Icons for assay design and configuration of the reader are included in an initial control window, as well as those to start assays, such as the ‘plate in’ and ‘go’ icons. All of these initial interfaces are easy to navigate and obvious. The reading mode (absorbance, fluorescence) is also controlled in this top level as well as assignment of filter positions in the filter wheels.
Assays can easily be designed in ‘layers’. For instance, an initial set up is created that defines parameters such as plate type, whether the test completes a full assay at one well (well mode), or whether all the wells are read one after the other (plate mode), what filters are used and the time course of the assay (time-course or single point). Then, using different icon buttons within this window, other information is added such as what wells in the plate are actually read (the same assay can be used for 1-well or 96-wells in the same plate), what additions are made and so on. The degree of precision within the controls is amazing, for instance the rate of solution addition can be controlled and the magnitude of shaking can be varied. Such features are particularly important for cell-based assays. Assays can be designed for 6-well to 384-well plates and the dimensions of many commonly used plates (e.g. Costar, Greiner) are pre-programmed, although other plate designs can also be added. Finally, assays can be observed in real-time to assess progress, and macros for some data processing are included. Conveniently, data is stored in Excel format.
The reader itself is approximately 19 inches wide, 17 inches deep and 11 inches high. Provision needs to be made for the plate carrier to open at the front (~5 inches) and also for access to the top of the reader where solutions for additions in assays are stored. The design of the reader is very tidy - there are no tubes, cables or bundles of electrical wire visible. Indeed, only when the top of the reader is open are the fiber optics and solution delivery tubes visible. The hardware is also sturdy and easy to work with, filters can be changed in under 5 minutes.
Other important performance features worth consideration, in addition to ease of use, are sensitivity, wavelength range and speed. In terms of sensitivity, the specifications indicate that 2 fmol of fluorescein per well can be detected. In real ‘cell’ terms for instance, this means that reasonably well GFP-transfected cells can easily be detected above background fluorescence and relative transfection levels determined. The spectral range is 240-740 nm, and so just about all commonly used fluorophores can be used. Filters can be obtained from BMG Labtechnologies or Chroma, so there is a wide choice of excellent quality filters available. Finally, a 96-well plate can be read in only15 seconds in the plate mode.
Although I have no experience with other plate reader, after extensive use of BMG’s FLUOstar I am struggling to find anything bad to say. In all performance aspects the reader seems to be excellent. Importantly, the interface to the reader is concise, simple and intuitive and assays can be developed in a very short time.
Peter Haggie, Ph.D.
University of California, San Francisco