Gel imagers (also called gel docs) are typically used by research labs interested in molecular biology. An individual lab may have access to its own a gel doc, or a department may purchase a system for multiple labs to use collectively. When choosing the right gel doc, the number of parameters considered can feel overwhelming. What specific capabilities must the new imager have to meet your research needs? Camera resolution, application choice, system size, and cost are all factors that go into making the right decision.
A modern gel imaging system can carry out many applications beyond basic documentation of gels using white or UV light. Gel imagers are light tight and if equipped with the right camera, can detect even the faintest signals. These powerful instruments can detect chemiluminescence for chemiluminescent Western blots or fluorescent signals from tissues, culture dishes, and arrays.
As image capture enthusiasts, Azure Biosystems understands better than most what goes into choosing the perfect gel imager for your lab. This article was written to guide you in choosing the best gel imager for you.
5 features to consider when choosing the right gel imager
1. The applications you use most often
Common applications involving a gel doc include imaging DNA gels, protein gels, Western blots, and Southern blots, and colony counting on plates. Basic gel docs support fewer applications (think white-light or UV gel documentation), while more advanced systems open the door to more complex applications (such as chemiluminescence, tissue imaging, multiplex fluorescence, and more).
When choosing a gel imager, take inventory of the different assays you need to image. Gel imagers can carry out a variety of imaging applications to detect and analyze nucleotide or protein gels and blots. Specifications can widely vary from system to system. Each system has specific capabilities depending on how the instrument is outfitted. Do you need to image DNA gels, Western blots, microwell plates, or more? If you need to solely image DNA gels for genotyping purposes, the type of gel imager you need will be different than another lab that needs to be able to image gels, fluorescent membranes, and colony assays.
Additional resource: Azure Imager Comparison
2. Ease of use
Efficiency is key! When you’re busy with a long list of experiments, relying on equipment that is straightforward and easy to use saves both time and energy. Image capture software should be intuitive. When looking for a gel doc, consider how easy it will be to use it. When comparing software from system to system, choose the software that takes you from sample to saved image in the least number of steps.
We understand training users to utilize new lab equipment can be time consuming. With this in mind, the engineering team at Azure has developed an intuitive user interface that’s quick to understand, simple to operate, and effective. The imager’s software allows you total customization over imaging protocols, while still ensuring repeatability from sample to sample.
Azure Imagers also have Auto-Focus; regardless of gel size, all images are in focus without needing manual adjustment. Other ease-of-use features include Auto-Exposer, which chooses your sample’s best imaging time, and Cumulative mode, which helps you choose the best exposure for chemiluminescence samples.
3. Camera resolution and sensitivity
Compared to film, digital imaging offers wider dynamic range and more accurate quantitation. Consider the camera properties when comparing gel docs. The f-stop or aperture is an important value to consider, especially for chemiluminescence.
The quality of the data you get from a gel imager depends on the camera. The higher the megapixels, the better the resolution and clearer the images. Higher resolution images allow better differentiation of bands or spots that migrate close to each other on 1D or 2D gels. Azure Imagers use high-resolution CCD cameras, up to 9.1 MP.
Azure Imagers are designed for high sensitivity imaging, capturing maximum light output from the sample. This is achieved by having the camera directly above the sample as close as possible for best light collection efficiency (figure 1). This direct light capture design is optimal for imaging chemiluminescence and fluorescent low light samples and consistently generates sharp, clear images.
Azure Imagers have a small f-stop and wide aperture. The smaller the f-stop value, the wider the aperture, and the more admitted light. Smaller f-stops drastically reduce exposure times. Lenses are now available on CCD imaging systems at f 0.95.
4. Choose an upgradeable gel imager
A very handy (but often overlooked) feature in a gel imager is the ability to make future upgrades. There are several reasons for needing to upgrade, such as expanding research needs, initially saving budget with a lower-tier model, and more. The Azure 200, 300, 400, and 500 can be easily upgraded to accommodate additional applications. Check out the graphic below to compare Azure Imagers.
Not all imagers offer the option for future upgrades, so be sure to check before purchasing. Most Azure Imagers are upgradeable to include additional light sources and filter combinations.
5. Space constraints
Gel imagers can vary significantly in size. Before purchasing a new gel imager, consider the space you have available in your lab and on your bench for the new instrument.
Systems that are operated with an adjacent external laptop or computer system can be clunky because they take up space on your bench that you might not have to spare. To save space, all Azure Imagers come with integrated touchscreens, but if you prefer to use an external PC, that option is available too.
Azure Imagers are half the size of some competing systems (Figure 2). At 42 x 56 x 33 cm, their small size translates into more bench space for other applications.
6. Bonus: Cost
The cost of gel imagers can vary from as low as $10,000 to as high as $80,000. The costs are dependent on your applications, the features you would like included in your gel doc, and add-ons. It’s always best to compare costs of similar systems across manufacturers to ensure you are getting the best system your budget allows for. If you already have an older system collecting dust, but you’re in need of a new system to better suit your needs, consider trading in your current system to offset the cost of a new Azure Imager.
Once the functionality and parameters of gel imagers are understood, you can use the information provided above to determine which gel doc is right for you. When choosing a gel doc, start by considering your research applications that require an imager. With these applications defined, the parameters needed in the gel imager are determined, and the right gel doc can be easily selected.
Considering these six aspects will allow you to select the right gel imager for you and your research needs. Once you’ve narrowed down your needs, contact an Azure rep to receive pricing on a new gel doc.