Thermo Fisher GeneFrames are adhesive spacers widely used in bacterial cell biology to make small sealed agarose pads on microscope slides for time lapse microscopy. The GeneFrames protocol was developed by Jan-Willem Veening and is available on JoVE. They work well for obligate aerobic bacteria such as Bacillus subtilis because it is straightforward to cut large air spaces either side of a narrow agarose pad within these frames.

Unfortunately, Thermo discontinued these items in 2025. BioRad FrameSeals, which as far as I can tell are the identical product under a different brand name, are also either discontinued or soon to be discontinued.

I have been looking for an alternative to this product and record the results of mine and other’s investigations here. Based on pricing and initial tests, the iSpacers mentioned below are the best replacement for GeneFrames.

  • iSpacers from SUNJinLab appear to be a promising solution. The company said they can make custom sizes. Prices look good: $20 for 50, $80 for 250. Thanks Ivan Volkov and George Churchman for finding these. We have now tested these and the 0.3mm thick iSpacers work well for timelapse microscopy of *Bacillus subtilis. We will use these going forward. If we have any further updates as to their performance I will post them here. We are planning to purchase a custom size that matches GeneFrame laterl dimensions, as the standard iSpacers are too big to fit 22mm coverslips.

  • Grace Biolabs have recently released SecureSeal Frames, a GeneFrame compatible replacement product. My lab have tested the prototype version of these and they work fine for Bacillus subtilis time lapse microsopy. However, at $115 for 25, they are quite pricy at 4x the cost of the old GeneFrames.

  • There is probably a good DIY solution. The key step would be to identify a suitably non-toxic double sided adhesive sheet material. Hobbyist die cutters or makerspace laser cutters could be used to cut the sheet.

Author: Séamus Holden