PF4 and infection: Pf4 assumes multiple roles during infection, including biofilm matrix stabilization 9, acting as an immune-decoy 26 and increasing antibiotic tolerance 10, hence nanobodies targeting Pf4 could have multiple use cases against P. aeruginosa. Directed evolution to increase nanobody affinity 47 as well as conjugation to molecules that degrade other matrix components or activate the host immune system could increase nanobody potency in the future 48.