frequently chosen strategy to increase the formulation viscosity, preventing unintended leakage and enhancing drug bioavailability when applied to body surfaces such as the intact skin, injured/infected areas, the mucous vaginal membrane, the bladder wall or the eye. For instance, the local administration of a fibrin hydrogel incorporating resiquimod-loaded phosphatidylserine-enriched liposomes (PSL-R848) was efficient to combat intracellular S. aureus infection in macrophages, which overexpress phosphatidylserine receptors. Once delivered, the resiquimod triggered the macrophage switch from a phenotype conducive to bacterial survival (M2-like) to a more antibacterial one (M1-like). This immunomodulatory treatment, easily administered by spray at the site of infection, may serve as a promising alternative to to systemic antibiotic administration (Figure ). staining. Adapted with permission. Copyright 2023 Elsevier.