Laboratory UV crosslinkers: how can DNA or RNA be permanently fixed to a membrane?

UV crosslinkers are benchtop instruments that deliver a precisely controlled ultraviolet dose in mJ/cm². Essential in molecular biology, they permanently immobilise DNA or RNA onto nylon or nitrocellulose membranes for blotting workflows. They are also used for photopolymerisation, targeted surface decontamination and photoactivation. Modern models control energy via an internal radiometer, ensuring reproducible exposure despite lamp ageing. Wavelengths 254, 312 or 365 nm, stainless-steel chamber, door interlock and presets complete the package.

What are the different types of UV crosslinkers, and how do you choose the right one?

First, there are UV crosslinkers at 254 nm, dedicated to nucleic acid fixation with UVC, ideal for Southern, Northern and dot blots. Other versions favour 312 or 365 nm for photopolymerisation, photoactivation and certain materials testing. Multiband models combine several wavelengths and pre-set programmes.

On the control side, two approaches: a simple timer or energy control. This relies on an internal sensor measuring irradiance and stops exactly at the programmed dose, ensuring consistent results despite lamp ageing or sample distance. It’s the go-to choice for reproducibility.

Chamber design drives uniformity: highly reflective stainless-steel walls, an adjustable shelf, ventilation, and a door interlock that shuts off emission as soon as you open it. Also check usable capacity, dose range, calibration, blotting presets and CE compliance.

Recent trend: UV-LED sources at 365 nm, mercury-free with improved stability, and ozone-free tubes to limit emissions. Whatever the system, replace lamps at the recommended interval and dispose of them via dedicated waste streams.

Type	Principle	Applications
254 nm with energy control	UV-C measured by dosimeter, stop at target dose	DNA/RNA crosslinking, blots, DNA decontamination
365/312 nm	UV-A/UV-B for photopolymerisation	UV bonding, photoactivation, materials testing
Programmable multiband	? selection and dose/time programmes	Multi-protocol R&D platforms

In which applications is a crosslinker used?

• Life sciences : DNA/RNA immobilisation onto nylon/nitrocellulose membranes for Southern, Northern and dot blots; hybridisation optimisation.
• Quality control : targeted decontamination of residual DNA on small non-critical tools and PCR workstation surfaces, as a complement to chemical procedures.
• Chemistry and materials : crosslinking of resins and UV adhesives, varnish and ink testing, adhesion and cure-kinetics control.
• Pharma / cosmetics : rapid photostability assays, curing of UV coatings and packaging-compatibility studies.
• Environment : photodegradation studies and simulated irradiation on model matrices.
• Teaching / core facilities : protocol reproducibility and training in blotting techniques.

The different types of crosslinkers available

Frequently asked questions about laboratory crosslinkers

Which wavelength should I choose for my nucleic acid blots?
To fix DNA/RNA onto a membrane, favour 254 nm (UVC). 312/365 nm are more suited to photopolymerisation and photoactivation.

Do I need a timer model or energy-controlled?
Energy-controlled operation cuts off at the set dose (mJ/cm²) and compensates for lamp ageing, delivering better reproducibility than timers alone.

How do I check irradiation uniformity?
Map the dose with dosimetry paper or a radiometer, adjust the tray height, and inspect the condition of lamps and reflectors.

What are the key safety precautions?
Interlocked door, UV shield, appropriate PPE. Never open while emitting; ventilate the area and use ozone-free tubes where available.

What day-to-day maintenance is required?
Clean the stainless-steel chamber, verify calibration, replace lamps periodically (up to ~8,000 h depending on model) and test the internal sensor.

Can a crosslinker be used to sterilise equipment?
It degrades residual DNA effectively at 254 nm. It is not a medical steriliser; combine with validated methods for sterility.

Do UV-LED versions offer a real benefit?
At 365 nm, LEDs provide stability, instant start-up and no mercury. Check the useful dose and compatibility with your protocols.