Accelerated protein retention expansion microscopy using microwave radiation

Summary

Scientists have developed a faster way to examine brain tissue at extremely small scales using a combination of expansion microscopy and microwave radiation. Instead of waiting days for tissue samples to process, the new method cuts the time down to hours while maintaining the same quality of detailed images. The technique was successfully tested on tadpole and fruit fly brains, showing it could be useful for studying neural structures and potentially applied to studying brain diseases like Alzheimer’s.

Background

Protein retention expansion microscopy (ExM) is a powerful technique that enables nanoscale resolution imaging by isotropically expanding fixed tissue on conventional diffraction-limited confocal microscopes. However, the complete ExM protocol is time-consuming, typically requiring 2-3 days or longer when combined with immunohistochemistry, limiting its practical application in research.

Objective

The study aimed to develop and validate an accelerated ExM protocol using microwave (M/W) radiation to reduce processing time while maintaining superior resolution and signal-to-noise ratio. The researchers adapted the M/W-assisted ExM protocol to different model organisms and tissue types to demonstrate its versatility.

Results

The M/W ExM protocol successfully reduced processing time from multiple days to hours in X. laevis and from 6 days to 2 days in Drosophila whole-brain tissue. The method maintained superior resolution comparable to conventional ExM, preserved tissue integrity and nuclear morphology, and yielded significantly higher linear expansion factors than conventional ExM in both model organisms.

Conclusion

M/W-assisted ExM provides a significant advancement in microscopy efficiency without compromising image quality or resolution. The protocol demonstrates versatility across different organisms and tissue types, and with appropriate parameter optimization, can be readily adapted to other ExM variants and biological systems to accelerate expansion microscopy experiments.
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