Chitosan-Enhanced Polymeric Microneedles: Innovations and Prospects in Drug Delivery — A Review

Transdermal drug delivery has emerged as a promising alternative to conventional administration routes, offering painless, minimally invasive, and efficient therapeutic options. However, the skin’s natural barrier, particularly the stratum corneum, limits the delivery of many macromolecules such as proteins, peptides, and vaccines. Microneedle (MN) technology has revolutionized this field by enabling the creation of micron-scale channels that bypass the skin barrier without causing pain or significant tissue damage. Among the various materials used for microneedle fabrication, chitosan—a natural, biocompatible, biodegradable, and bioactive polymer, stands out as particularly advantageous. This review highlights recent advances in the design, fabrication, and application of chitosan-based microneedles for transdermal drug delivery. Various fabrication techniques, including casting, micromolding, and electrospinning, have been explored to optimize mechanical strength, drug loading, and controlled release properties. Chitosan’s intrinsic antimicrobial properties, permeability-enhancing ability, and capacity for sustained drug release make it ideal for diverse biomedical applications ranging from protein delivery and pain management to antifungal therapy and wound healing. Special emphasis is placed on chitosan-based microneedle platforms for insulin and vaccine delivery, which demonstrate improved bioavailability, patient compliance, and therapeutic efficacy. The review also discusses current challenges in large-scale fabrication, drug stability, and clinical translation, alongside future research directions focusing on stimuli-responsive systems, combinatorial drug delivery, and patient-centric designs. Overall, chitosan-based microneedles represent a versatile and transformative platform poised to expand the scope and impact of transdermal therapeutics globally.