Real-Time Digital Autoradiography 
Technology Comparison
The Biomolex Microarray Reader technology features real-time digital acquisition and imaging of radionuclide emissions. The detector, a Double-Sided Silicon Strip Detector (DSSD), consists of 560×1260 strips in a Cartesian grid on each side of a silicon core, with a 50 μm pitch and energy detection as low as 20 - 25 keV. The Biomolex Microarray Reader is the first commercial product for biomedical imaging using a silicon strip detector and is the first instrument ever enabling real time detection and subsequent separation, based on registered energy spectra from different β-emitters. Signals from different β-emitters for any chosen region on the sensor can be separated and ratios of the different isotopes can be calculated with advanced statistical algorithms.
Double Sided Silicon Strip Detector
Size: 2.8x6cm
Pitch: 50μm -705,000 pixels
Energy range: 20-800 keV
Event rate > 10K/s
User-Friendly and Intuitive GUI
Standard radioisotope labeling protocols for Protein and DNA labeling can be used. The Biomolex readout format is compatible with standard data analysis software. The Biomolex Reader offers “out of the box” usability, since most protocols would already be known to users.
Ultra Sensitive Imaging
Real-Time Digital Imaging. The exact position and the energy deposition of each emission is displayed on-screen in real time. Image acquisition begins as soon as the sample is loaded into the machine.
Competitor Imager: 72h acquisition
Biomolex 700 Imager: 72h acquisition
Large Number of Radiolabels
Pixel wise registration of events and energies will, in certain cases, also enable separation of signals from different isotopes. The Biomolex Microarray Reader readily detects signals from a wide range of radioactive isotopes used in molecular biology (i.e. 33P, 32P , 35S, 131I, 18F, 99T).Innovation (sfi)² (SFI) Isotope-based labeling and detection can be adopted without having to make major changes to existing labelling protocols/ techniques. The use of radioisotopes offers several advantages over conventional protocols for labeling and detection.
Detection of Low Energy β- Radiation
The core technology in the Biomolex Microarray Reader is based on Ideas ASA’s world leading technology for detection of low energy β- radiation. Ideas is a Norwegian high-tech company developing detection modules (camera heads) enabling high precision detection and imaging of γ- and β- radiation as well as X-rays. Their technological solutions are the leading standards adopted by a large number of global technology players and prestigious scientific communities. Their client list includes names like Siemens, GE, Philips, MIT, Harvard, Oxford and NASA. For further information on Ideas please visit www.ideas.no.
The Biomolex Microarray Reader technology offers real-time digital imaging of radioactive emissions. The detector, a double-sided silicon strip detector (DSSD) consists of 560×1260 strips in a Cartesian array on each side of a silicon core with a strip pitch of 50μm. The DSSD will respond to energy depositions in the silicon core of the sensor. For each radioactive event that hits the detector the energy and the exact position, with a precision down to 50μm is registered. The unique sensitivity of the Ideas-patented read-out electronics assures excellent signal to noise ratios and enables particle detection at energies as low as 20-25 keV. During a recording, the sensor is bombarded with a high number of β-particles. For each of the pixels/strip intersections (50x50μm) the exact energy of all events are registered. Using advanced statistical algorithms, signals from different β-emitters for any chosen region on the sensor are separated and the ratios of the different isotopes used can be calculated.
High Sensitivity
Most researchers rate sensitivity as one of the three most important aspects in their experiments and there is a continuous effort to optimize protocols to increase overall sensitivity.
Isotope based labeling and detection protocols applied in tissue imaging and protein expression analysis are more sensitive than conventional methods based on fluorescence. Sensitivity for detection of rare targets has proven to be a serious drawback for many imaging technologies. In many cases, low abundance rates in combination with limited sample supply (e.g. analysis of individual patient samples) require the use of detectors that are more sensitive than conventional scanners. The Biomolex Reader’s sensitivity meets these stringent requirements.
Dynamic Range
In a typical cell it is not unusual for the concentration range of labeled metabolites (highest and lowest) to exceed 4 - 5 orders of magnitude. The full potential of medical imaging will only be realized when rare targets can be detected simultaneously with more abundant ones in the same assay. A key assumption in imaging analysis is that the quantified signal intensities are linearly related to the intensity of corresponding labeled metabolites. Recent research shows that the linearity of signal intensity for the Biomolex Reader (>5 orders) is superior compared to the 3 - 3.5 orders of magnitude typical of fluorescence scanners and phosphorscreens. (Ramadas et al, Genome Biology, 2001, 2(11))
Protein Labeling
Due to the complex nature of proteins, there are additional and more important reasons why isotope labeling will play a dominant role in the future of protein microarrays. Isotope-based protocols support in vivo labeling and thus enable uncomplicated and more accurate labeling than fluorescence based protocols. Most protein microarrays will depend on the interaction between different proteins and/or between proteins and other biomolecules. It is therefore crucial that the applied label neither interfere with the native structure of the target molecule nor occupy important interaction sights on the target. In this respect isotopic labels offer a great advantage over fluorescence labels since they are incorporated into the target as a natural element, and not as a large bulky molecule attached to the surface of the target.
Kinase Arrays
All kinases transfer ATP terminal phosphates onto specific protein and peptide sequences. There are basically two major types of protocols for labeling and detecting kinases: radioisotope based protocols and fluorescence based protocols. The former measure the direct transfer of phosphates onto the targets, while the latter indirectly detect the phosphorylation through a fluorescent labeled antibody. Direct labeling and detection using radioisotopes offers great advantages over the fluorescence protocols in that they measure the direct transfer of the phosphates onto their target. In contrast, fluorescent protocols depend on specific antibodies for each phosphorylated target. Radioactive assays work independently of the type of kinase/substrate being assayed. Antibody based assays only work on those phosphorylated substrates that are recognized well by antibodies. Commercial antibodies are available only for the most common serine/threonine kinases. Thus one usually needs to generate custom antibodies against the amino acids in the kinase substrate recognition site. Radioisotope labeled ATP’s are commercially available from suppliers like GE-Amersham and PerkinElmer, and although there has been a move away from radioactivity in recent years, there is still an estimated $30 million worldwide market for radioactive assays.
Autoradiography
The Biomolex reader supports autoradiography and molecular imaging applications. It enables “real time” study of in vivo biological processes. Typical pharmacogenetic applications would include monitoring the efficiency of delivering foreign genetic material and elucidating gene therapy delivery principles. With multiple labels it is possible to monitor several biomolecules or processes simultaneously, and the information can be used to monitor distribution patterns and ratios for the differently labeled biomolecules.