Poly (lactic-co-glycolic acid)-based microneedles for drug delivery across different biological barriers

Microneedles (MNs) are micro-sized needles that were originally designed as minimally invasive and painless devices capable of piercing the main skin barrier, the stratum corneum, without stimulating nerve fibers, showing promising prospects as an alternative to other drug administration routes. Poly (lactic-co-glycolic acid) (PLGA) is a biodegradable and biocompatible copolymer with favorable mechanical properties, making it particularly suitable for fabrication of MNs for controlled-release drug delivery. This review provides a comprehensive overview of the design, fabrication, and therapeutic potential of PLGA-based MN systems across a broad range of applications, including transdermal systemic delivery, vaccine delivery and topical skin applications. Due to their exceptional virtues, PLGA MNs are further utilized in nontransdermal applications such as ocular, oral cavity, nasal, and other emerging uses that are presented. Eventually, toxicity and safety profile are discussed, and a concluding section on future perspectives is provided.