Interestingly, this employment of algal cells to deliver drugs is far more in keeping with the original meaning of the word which became "robot" - namely, "robota", which in many languages refers to forced work or slavery. So, in a very real sense, these are robots.
These are robots in the sense that the origin of the word has this meaning, but in contemporary English use "robot" refers to some kind of electromechanical machine, or sometimes a piece of software. But in my mind engineered algal cells don't really fit with contemporary English use of the word.
Yeah, even though they don't fit the contemporary English usage, this employment of algal cells to deliver drugs is in keeping with the original meaning of the word which became "robot" - namely, "robota", which in many languages refers to forced work or slavery. So, in a very real sense, these are robots.
Using 'robot' to denote just any "worker" seems to make no (terminologically) decisional sense, not theoretical nor practical - you could find better options.
It is, in this case, like tying cleaning rags on the paws of a household cat, and saying "There, I have a robot".
This very odd "employment" (well) of the term 'robot' just had me check for the meaning a bit more deeply:
it appears that "robota" is related to work after the subject was forced to work, with limited choice, by a "predicament", a "change of condition", namely chiefly by being orphaned (cpr. related latin 'orbus').
That seems to be the field in which the word should move.
(It also seems that some people in wiktionary.org are doing a very good job.)
* because those words appear in the abstract