Fabrication and evaluation of polymeric microneedles containing a chitosan-coated curcumin nanoemulsion: structural characterization and transdermal performance

Abstract

Curcumin is a natural compound with promising anticancer potential, but its clinical application is limited by its poor aqueous solubility and low skin permeability. To address these challenges, this study investigates the transdermal delivery of curcumin using dissolving microneedles (DMNs) fabricated using three different polymers: poly(vinyl alcohol) (PVA), hyaluronic acid (HA), and carboxymethyl cellulose (CMC). A chitosan-coated curcumin nanoemulsion (NE-Cur-CS) was prepared and characterized for its physicochemical properties, including particle size (26.37 ± 0.42 nm) and zeta potential (−21.90 ± 0.98 mV). NE-Cur-CS was incorporated into 10 × 10 pyramidal microneedle arrays, fabricated using the micromolding method. Structural and mechanical characterization showed that the PVA- and HA-based microneedles (639 × 238 µm and 566 × 299 µm, respectively) maintained their integrity under a 32 N compression force and successfully penetrated the stratum corneum, as confirmed by H&E staining. Permeation studies confirmed their ability to penetrate the stratum corneum layer. Permeation studies at physiological pH (7.4) showed curcumin release rates of 59.74% for HA-based microneedles and 17.71% for those made with PVA after 7 hours. These results indicate that the type of polymer matrix plays a crucial role in controlling the transdermal delivery efficiency of the curcumin nanoemulsion.