• Quantification and molecular weight determination
• Southern blots  
• Northern blots  
• Western blots  
• Gene amplification or protein chip image  
• Agarose gels stained with ethidium bromide or SYBR Green  
• Acrylamide gels stained with Coomassie Blue, SYPRO Red, SYPRO Orange, and silver stain  
• Quantification of dot blots  
• Colony and plaque lift analysis  
• Microplate assays, e.g. reporter gene assay. TOP

Cool Imager^™ Workstation is a sophisticated device with an innovative hardware design. See the description below to learn the details of how the instrument works.

Two-Stage Pelitier Cooling System

In order to detect low light samples (such as chemiluminescence) the detection system needs to be very sensitive. Thermal excitation within the CCD chip, which converts the light into electric charges, adds electrons to the detected signal. These extra electrons reduce the sensitivity. Using a double-stage Peltier cooling system, the CCD chip of the Cool Imager^™ Workstation is cooled to -45^oC to avoid ‘thermal noise’ and achieve maximum sensitivity. In order to achieve such a low temperature, a vacuum is applied to the camera. 

CCD Chip

The central part of the camera system integrated in the Cool Imager^™ is a CCD chip (CCD = Charge-Coupled Device) that converts incoming light into an electrical signal. The CCD chip is a small piece of silicon 20.5 mm wide and 16.4 mm high, divided into 756 rows, each consisting of 581 individual elements, referred to here as pixels. Each of the pixels is an individual light detector that can measure the amount of light hitting the pixel area over a certain period of time.

The number and sensitivity of the pixels define the quality of a CCD camera. The number of pixels determines the spatial resolution of the final image. This allows the exact measurement of very closely spaced bands as well as the use of high density MTPs. TOP

The sensitivity of the pixels and the electronics of the camera determine the lower detection limit and the linearity of the instrument. During the readout process, the electric charges collected by the pixels during exposure are converted into an electrical signal with 16-bit resolution. The dynamic range of the Cool Imager^™ is very wide at 1:10,000. This means that the Cool Imager^™ can measure a 1 pg band on the same blot as a 10 ng band. By comparison, X-ray film has a low dynamic range of 1:100. On a blot a 1 pg band and a 100 pg band could be detected simultaneously, but > 100 pg would not be distinguishable from 100 pg. Higher concentrations are often seen as larger bands, though linearity is lost.

This wide dynamic range greatly enhances the Cool Imager^™’s quantifying ability. In addition, only one exposure is required to capture faint and strong signals whereas with X-ray film multiple exposures are required. When data points are plotted on a graph and the points are in a straight line, the data is linear. Therefore linearity refers to how well data points fall into a straight line. Although linearity is distinct from dynamic range, the dynamic range of the medium affects linearity. For example, X-ray film has a poor dynamic range at 1:100. Even within that dynamic range, the response of the X-ray film to light, i.e. oxidation of silver grains, is nonlinear. Thus, X-ray film is not suitable for quantification. In contrast, the Cool Imager^™ has a dynamic range of 1:10,000 and is linear over this entire range.

In standard chips, very strong signals can cause an electron overflow into neighboring pixels. This can result in highlighting and flaring of bands. The chip of the Cool Imager^™ has a special feature called antiblooming that allows a pixel to uptake a 1000 x higher light intensity than a standard chip without overflowing into neighboring pixels. TOP

If you want to learn more how a CCD chip works and how the Cool Imager^™ Workstation optimizes the imaging process please continue to read the next section.  

The traditional biological imagers for analyzing DNA gels cannot be used for the detection of chemiluminescent signals due to their low sensitivity and high background. In order to detect chemiluminescent signals, the CCD cameras have to be cooled to a very low temperature to reduce so called  "Hot Spots". Cool Imager^™ by Viagene Biotech is integrated with modern techniques including, computer technology, microelectronics and semiconductor technology. Cool Imager^™ is a digital imager which is used for capturing and analyzing biologic images with specific design for picking up chemiluminescent signals. The comparison of it with other devices on the market is shown in  Table 1 and 2.