Mucoadhesive nanosystems for vaginal microbicide development: friend or foe?

Topical microbicides are a promising strategy in the prevention of vaginal and rectal HIV transmission as well as other sexually transmitted pathogens. The perspective of developing nanotechnology-based systems for topical microbicides seems to be useful because important features such as enhanced drug release, targeting, and epithelial penetration can be achieved. However, the interaction of nanoparticles with the mucus fluids that cover the cervicovaginal mucosal epithelium, which can work either as a docking point or as a barrier for diffusion, has been frequently neglected. In this review, we discuss the principles of nanosystems' adhesion to the mucosal tissue and how this relates to the development of optimized microbicide formulations.