Development of Transdermal Formulation Integrating Polymer-Based Solid Microneedles and Thermoresponsive Gel Fucoidan for Antiaging: Proof of Concept Study

Skin can be damaged by intense and prolonged exposure to ultraviolet (UV) radiation. Photoaging and acute damage from sun exposure result in collagen degradation and enzymatic activity decline in the skin. Fucoidan (FUC) exhibits potential antiaging properties, including collagen synthesis promotion and enzyme activity inhibition. However, FUC's limited ability to penetrate the skin layers due to its large molecular weight makes it a challenge for topical application. In this study, we successfully developed a new approach by integrating thermoresponsive gel (TRG) containing FUC with solid microneedles (SMNs) as a delivery system. TRG is formulated using a combination of Pluronic F127 (PF127) and Pluronic F68 (PF68) polymers, while SMNs are made from a mixture of poly(vinyl alcohol) (PVA) and poly(vinylpyrrolidone) (PVP) polymers with a variety of cross-linkers. Based on the results of ex vivo testing, it was shown that more than 80% of FUC can be delivered using the optimized formula. Furthermore, the results of the in vitro blood hemolytic test showed that TRG-FUC-SMNs were relatively biocompatible. In vivo antiaging activity tests using a rat model exposed to UV for 14 days showed that histological assessment, skin elasticity measurement, wrinkle evaluation, and skin moisture content had no significant differences (<i>p</i> < 0.05) compared to the positive control group. In contrast, a significant difference (<i>p</i> < 0.05) was observed when comparing the TRG-FUC-SMNs group with the group that received only TRG-FUC without pretreatment and negative controls. These findings suggest that FUC has potential to be delivered using the TRG system in combination with SMNs to harness its antiaging properties.