What is Western Blotting (also known as immunoblotting)? A biochemical process, used by scientists and researchers, to specify proteins within complex samples. Western blot imaging can be used to identify the atomic weight, the number of proteins in a sample and post-translational alteration of proteins. This information has many applications from simple research tasks to analysis and diagnosis of infectious diseases. A western blot imager is an effective device to monitor changes in proteins, focusing on expression and modifications.
A Western Blot
Discerning and qualifying proteins amongst multiple cell lines is central to the study of cellular proteins. Conventional western blot techniques can provide this data, however multiple takes and numerous time-consuming calibrations may be necessary to achieve this. Additionally, traditional western blot imaging systems capture strong signals from nearby bands along with the target protein. Existing Western Blot imaging systems can be bulky, expensive and have poor sensitivity, because they use either scanning line sensors or lens-coupled CCDs.
Traditional Western Blot Techniques
X-ray Film
The image of the protein sample is captured on X-ray film in a dark room. The procedure has a high sensitivity, and the finished image has no optical signal loss because the method is a form of 1:1 imaging. The use of X-ray film in western blotting has negative points:
· High maintenance and overhead costs, as the procedure requires a dark room, reagents, and other chemicals.
· The chemicals required for processing the X-ray film are harmful to the environment and require safe disposal.
· Preparing and processing the X-ray film is very time consuming.
· Poor signal acquisition and limited dynamic range can result in low-accuracy images that could require multiple takes.
· The method is not digital and therefore requires the developed film to be scanned.
Cooled Lens Coupled CCD
An alternative method is cooled CCD western blot which uses a scientific grade cooled CDD-based camera coupled to a lens. Unlike X-ray film, the cooled CCD method provides accurate quantitative imaging, a wider dynamic range and digital documentation.
Despite its advantages, cooled CCD western blot imaging systems have their own setbacks, which include:
Low sensitivity and a high optical signal loss resulting in long acquisition times.
A narrow quantitative range.
blurred images due to imperfect focusing.
Using large area CMOS Sensors in Western Blotting for faster, more accurate results
Conventional western blot technique v Spectrum Logic 1:1 Imager
Like X-ray film, CMOS Image Sensors can be used for direct, one-to-one contact imaging without a lens. This maximises sensitivity by avoiding the optical light loss that is inevitable in a lens-based system. Because there is no lens in the system, it cannot be out of focus and therefore provides very sharp images. Unlike X-ray film, using state-of-the-art CMOS image sensors, means the output is a digital image or document. Also, it has effectively unlimited dynamic range by virtue of its ability to digitally combine multiple images. In this way, CMOS Image Sensors combines the advantages of X-ray film with the advantages of lens coupled, cooled CCD cameras.
Spectrum Logic CL1510 1:1 Imager
Spectrum Logic has developed sensors and a prototype western blot imager to enable accurate scanning in a laboratory setting. The Spectrum Logic CL1510 1:1 imager uses a unique, large-area CMOS image sensor coupled to fiber optic faceplate for 1:1 imaging without a lens or scanning. This allows the Spectrum Logic CL1510 1:1 imager to capture much more of the light emitted during the assay, making it more sensitive. 1:1 imaging with a fiber optic plate also provides very sharp images and is not prone to inaccurate focusing of a lens. With an onboard computer and light-tight, waterproof bench-top enclosure, the CL1510 1:1 imager can simply be plugged into a laptop and turned on, achieving results in minutes.
1510HS-20-WB-SA Sensor Assembly
IS1510 Sensor