Using LEDs as a low-cost source to detect GFP and DsRED

Fluorescence detection components are too costly to be installed in every stereoscope. Often, our fluorescent markers are very bright and do not require the full capacity of such equipment. Here we present an LED setup that costs only about $100 and can detect bright fluorescent markers such as myo-2::GFP.

You will need:

• Xacto helping hands or anything that can position the LED (Amazon.com).
• Lamp cord with a switch. Make sure that the wire size is 18AWG (local hardware store).
• 17-watt Xitanium LED driver (LED Supply.com).
• Xitanium driver connector (LED Supply.com).
• Luxeon V Star LED: Royal-Blue (LED Supply.com) for GFP, or Green (LED Supply.com) for dsRED.
• Heatsink (LED Supply.com).
• Spot lens (LED Supply.com).
• Optic holder (LED Supply.com).
• Emission filter: Roscolux #12 Straw for GFP, or #19 Fire for dsRED; Optional excitation filter: Roscolux #4290 CalColor 90 Blue for GFP, or #389 Chroma Green for dsRED. You can buy a 3"x5" booklet from Edmund Optics or buy individual sheets from your local lighting store. I found the latter to be a better deal.
• Non-conductive glue. I use silicone adhesive (Devcon, part No.12045) that you can buy a local hardware store.
• Additional tools: soldering iron, wire cutter, wire stripper.

To assemble:

1. Use a wire cutter to cut the socket off the lamp cord. Use a wire stripper to strip the ends. Apply some solder to the ends. Insert the ends into the sockest on the driver. Make sure that the neutral/line ends on the lamp cord match those on the driver. That is, the cable that is linked to the wider blade (neutral) should be inserted into the white socket on the driver.
   
2. Plug one end of the connector to the driver. Cut off the other end, strip the wire. Follow the + end on the driver and solder the cable to a + end on the LED. Similarly, connect the - end on the driver to an - end on the LED.
   
3. Snap the lens onto the holder. Glue the holder onto the LED, be careful do not put glue on the lens. Cut off the plastic cover on the heatsink to expose the sticky side, and stick the LED onto the heatsink. That's it. You've finished the assembly.
   
4. The emission filter can be simply taped under the microscope objective. I staple it between two cardboards for easier handling. The optional excitation filter can be glued to the lens by applying a small amount of glue on the edge of the optic holder.
   
5. Use the helping hands to position LED to reach max fluorescence.
   

This setup has a long operating life, requires no warm-up or cool-down time, and has no radiation. However, it can only detect strong signals.

We have used the setup to detect the following markers: myo-2::GFP (bottom left, an mIn1 animal), sur-5::GFP, ajm-1::GFP, and myo-2::dsRED (bottom right).

More information can be found at the Chin-Sang lab website.

We published this at the Worm Breeders' Gazette.