Do biologists use the word "solubilize" to mean "dissolve"?
I think I found an answer at Science Direct where multiple definitions are provided, among one from Thomson (2012):

Solubilization is the action of certain chemical reagents on organic materials (such as animal or plant tissue) that effects a structural breakdown (or digestion) into a liquid form that can then be directly dissolved [...]

and from Lau (2011):

Solubilization is the increase in solubility of a poorly water–soluble substance with surface-active agents. The mechanism involves entrapment (adsorbed or dissolved) of molecules in micelles and the tendency of surfactants to form colloidal aggregations at critical micelle concentration levels.

From these definitions I understand that solubilization is a process to make something dissolvable. The process of dissolving thus happens after the solubilization (definition #1) or during the process of solubilization process (definition #2). Thus, solubilization and dissolving are separate processes (definition #1) or dissolving is considered a part of the process of solubilization (definition #2).
So admittedly, at this stage I am unsure to what exactly the two terms mean exactly, but they are certainly not interchangeable terms.
And regarding your comment

...that it's not unusual for experienced biologists themselves to be unsure which is the proper term here. Even native English speakers

I totally second Bryan's response

Language is messy, scientific terminology included...

This is because terminology tends to stick after having been adopted widely, even if it proves to be incorrect. Consider for instance the fact that current always flows from + to - in schematics, but that electrons definiely choose to go the other way around. Scientific terminology is messy indeed.
References
- Lau, Preformulation Studies. In: Handbook of Modern Pharmaceutical Analysis: 173-233
- Thomson, Handbook of Radioactivity Analysis (3rd ed.) 2012: 575-623