Chitosan nanoparticles for mucosal and needle-free vaccination.

Chitosan nanoparticles are emerging as versatile vaccine carriers that enhance antigen stability, improve mucosal delivery, and strengthen immune activation. This review synthesizes advances in their biological functions, chemical engineering, fabrication, and performance across inactivated, subunit, and nucleic acid vaccines. It defines structure function principles that guide rational design for thermostable and effective immunization, highlighting the promise of needle free mucosal vaccination for scalable use across diverse settings.