Toxins are what make bacterial infections deadly. Nanosponges target the toxins instead of the bacteria, mopping it up and taking it to the liver to be filtered out of the body. The more we develop this the better. In conjunction with antibiotics this could save a lot of lives. Even alone, in cases where antibiotics don't work this could save a lot of lives by preventing damage long enough for the body's natural defenses to fight off infection.
This could even be good for people who are just at risk of bacterial infections. Since it mops up the toxins and toxins are just chemicals, they don't have DNA, the toxins aren't going to mutate and become resistant. This gives nanosponges far more therapeutic potential than antibiotics.