Effect of Resizing (Up Scaling) an Image on the Ability to Detect / Recognize Objects
It is theoretically impossible to add information by increasing the resolution of an existing image.

So from that point of view -- no.

However, I certainly find it conceivable that if you're using some canned algorithms they may be sensitive to pixelation.  Unless they're really lame, I would only expect this to be an issue if your original images are very sharp -- if the un-differenced objects tend to have blurry edges, either because of the limitations of your microscope or the properties of the objects themselves, then I'd think about trying what you suggest.

Otherwise -- you can't get something for nothing!