What is a microscopic hollow sphere made from a lipid bilayer referred to as?

The correct terminology for a microscopic hollow sphere formed from a lipid bilayer is a vesicle. Vesicles are small membrane-bound structures that transport substances within a cell and can also play a role in cellular processes such as metabolism, communication, and transport of materials. They are typically composed of a phospholipid bilayer that encapsulates an aqueous interior, allowing them to easily fuse with other membranes and deliver their contents.

In contrast, micelles are aggregates of lipid molecules that form in water, where the hydrophobic tails of the lipids face inward, away from the water, while the hydrophilic heads face outward. They do not create a hollow sphere in the same way that vesicles do.

Microspheres generally refer to small, spherical particles that can be composed of various materials, but they do not specifically refer to lipid-bilayer structures.

Liposomal spheres often describe vesicles created for drug delivery purposes, specifically those that contain lipids, but the more precise term for the structure itself remains vesicle. Thus, referring to a lipid bilayer sphere as a vesicle accurately captures its essential characteristics and function.