The Stratalinker UV Crosslinker from Stratagene is a very compact device for irradiating samples with defined amounts of UV energy. Our laboratory uses the instrument primarily for the cross-linking of nucleic acids to membranes for blots of various types, and also for crosslinking nucleic acids to glass slides. However, the Stratalinker can be used for any purpose where a precisely controlled amount of UV exposure is required.
We have found the unit to be very easy to use, with a simple cabinet design and control interface that is similar to a microwave oven. The majority of the front of the Stratalinker is an opaque door that allows access to the internal chamber where irradiation takes place. Inside is a set of UV tubes, starters and a sensor to measure the amount of energy delivered to the sample. The remainder of the front of the unit is a control panel displaying the time or energy required, and a simple keypad for entering the required numbers, along with a ‘start’ and ‘stop’ button. Although a comprehensive manual is provided, we have found that the Stratalinker is easy and intuitive enough that it is really not required. The Stratalinker can be programmed to operate in time or energy mode, in which case either a specific amount of time is measured during which the sample is irradiated or a specific amount of energy is delivered and the time is automatically varied. The unit also has ‘auto crosslink’ mode, in which a specific amount of energy is delivered that has been identified as the optimal cross-linking time for Stratagene’s own membranes. We have found that this mode works well for all membrane types.
A typical cross-linking procedure will typically take from 20 seconds to a minute or so, which is a great time saving compared to using an oven for crosslinking membranes. The crosslinker also avoids the problem of ignition of nitrocellulose membranes, and the brittleness that is also often caused by baking membranes. Although a conventional UV light box can be used for cross-linking, it is difficult to take measure the actual amount of energy supplied to your sample, as the intensity of irradiation changes with the age of the UV bulbs. The Stratalinker overcomes this problem by measuring the actual amount of energy falling on a defined area using a photocell detector.
Another benefit of the Stratalinker is its size. The external dimensions of the crosslinker are 46 cm × 22 cm × 26 cm. This allows us to keep the unit on the bench in our laboratory, without the need for a darkroom or other shielding that is typically required for a UV light box. It is also much smaller than a hot air oven. There is no safety cut-off built in to the Stratalinker, however, so if the door is opened whilst the unit is operating, it will not automatically switch off the UV. This seems like an oversight on behalf of Stratagene, but it does not pose a problem as long as the users are aware of it.
Scott Coutts
Department of Microbiology
Monash University, Melbourne, Australia