Referring to sliced sprites in Resources by name

I have a folder Resources/ItemIcons. Inside it is a spritesheet "rpgicons" and some number of sliced sprites from that spritesheet. One of them is called "potion" though. I am given the string "potion" by my script and I need to find the sliced sprite by that name.

There are many explanations of how to use LoadAll to get all the sliced sprites and then load one by index. However, I am interested in using Load to get just the one by this name. Only, it doesn't seem to work.

Is there something special that I have to put in the path to reference a sliced sprite that isn't required otherwise? How can I get my potion sprite just with its name, not its index?

[edit] Obviously you can iterate over the array of sprites found with LoadAll, but I'm hoping for something faster, built in. [/edit]