Scientists from my birth country, the Philippines, are said to have developed band-aids made from the fibers of the edible mushroom volvariella volvacea (incorporated in fibrous materials from agro-industrial wastes, alginate or stabilizer and textile fiber).
The mushroom induces the repair of tissues while inhibiting microbial growth. The band-aid itself is said to be non-toxic, non-allergenic, biodegradable, hydrophilic and permeates oxygen.
This beats the freshly-plucked guava leaves my grandmother used to plaster my scratched and (sometimes wounded) knees during my precocious years.
They say that the chitosan in the mushroom is the active agent. It is good to know that it is non-allergenic.
Also check out KytoStat bandages here . I think this seafood-derived chitosan is costly, but both probably perform the same function.
Interesting point about the guava leaves; coming from India, I have tasted many (:-),for no sane reason), but never used them for bandage.