Alginate/Chitosan Based Microneedles For Potential Transdermal Drug Delivery System

Abstract

Microneedles have shown promising potential in drug delivery and transdermal applications. In this study, biopolymer materials alginate (Alg) and chitosan (CS) were used to fabricate microneedles. Their shapes, mechanical properties, drug release behavior, and ability to be inserted into a skin model were investigated. At various Alg concentrations, microneedles were successfully fabricated, except for Alg 2.5%, where surface breaks and holes were observed. The unstable morphology at this concentration was attributed to an insufficient concentration of biopolymer chains during solidification. At Alg 3% and Alg 3.5%, the presence of more biopolymer chains improved morphology preservation. Chitosan crosslinking of Alg microneedles improved structural integrity by forming a polyelectrolyte complex. Chitosan addition significantly reduced tip diameter and height while maintaining base width, subsequently increased microneedle shrinkage properties. Mechanical testing demonstrated that Alg concentration had no significant effect on force endurance, while chitosan-crosslinked samples decreased compressive force endurance. Microneedle insertion tests confirmed that the microneedles were hard enough to penetrate the stratum corneum sublayer, and length measurements ranged between 500 µm and 600 µm. Alg/CS 2.5% samples exhibited the deepest insertion, while Alg 2.5% samples with cracks had the narrowest insertion. Studies on drug release showed that chitosan-crosslinked samples with higher Alg concentrations had faster cumulative drug release. This was because of more formation of polyelectrolyte complexes, which slowed down the drug release rate. Contrary to what was found in earlier research, the volume shrinkage of microneedles decreased as the Alg concentration in chitosan-crosslinked samples went up. This may be due to the cone shape of the microneedles and the ratios of polyelectrolyte complex formation. Overall, this study shows how Alg and chitosan-based microneedles are made, their shape, their mechanical properties, how they release drugs, and how they can be inserted. Further exploration of CS ratios and Alg concentrations can optimize microneedle characteristics for better microneedle applications.