Conclusion

The development of a more holistic mechanistic model allows the maximization of the FISH’s efficiency helping in the optimization of probe design and probe concentration. It is however apparent from this work that many of the characteristic time values obtained lack strong experimental support. In future works, these parameters could be further assessed experimentally, using fluorescent microscopy techniques such as fluorescence recovery after photobleaching (FRAP). With the current data, it was estimated that for bacterial cells the limiting step for diffusion is likely to be the peptidoglycan layer, whereas for animal cells the limiting step is more likely to be the diffusion of the probe through the bulk medium followed by the diffusion through the lipid membrane. The information provided here may serve as a basis to optimize FISH protocols and as a conceptual background for the interpretation of FISH as a specific case of a diffusion-reaction process.