Hydrocolloids are emerging as multifunctional materials for next-generation food, nutrition, and health applications. However, the simultaneous delivery of hydrophilic and lipophilic nutrients within a single hydrocolloid matrix remains a fundamental challenge due to mutual incompatibility, limited mechanical strength and uncontrolled release. In this study, we developed an O/W emulsion-based dissolving microneedle (DMN) system, stabilized by food-grade polyelectrolyte complexes (PEC), for the dual transdermal delivery of ascorbic acid (AA) and lycopene (LY), supporting a novel ‘Patch-Food’ concept.

A dual-network hydrocolloid matrix was designed by combining cationic chitosan (CS) and anionic hyaluronic acid (HA), forming a PEC network acting as physical crosslinking points within the PVA/PVP continuous phase. This system enabled stable co-loading of the AA-loaded aqueous phase (PVA/PVP/HA/CS) and the LY-encapsulated oil phase at a 1:9 (O/W) ratio (pH 5). The effect of CS concentration (0–2%) on the system was investigated in depth through rheological and microstructural analyses. Furthermore, the mechanical properties TA, XRD, dissolution characteristics, in vitro release patterns and DPPH antioxidant activity of the fabricated DMNs were comprehensively analyzed.

Rheological analysis revealed a unique non-linear viscosity behavior (0% > 2% > 1%) dependent on CS concentration. Microscopy visually demonstrated this mechanism: 1% CS induced a 'collapse' of the existing network via PEC formation (a ball-bearing effect), drastically lowering viscosity. In contrast, 2% CS caused 'bridging' between particles, leading to aggregation (intermediate viscosity). This structural optimization led to a significant improvement in mechanical strength, doubling it from ~20 N to ~40 N and ensuring reliable skin insertion. CS-induced bridging also enhanced emulsion stability.

DMN dissolution was tunable by CS concentration: low-CS formulations exhibited rapid dissolution (~15 min), whereas PEC-reinforced DMNs dissolved over 120 minutes, enabling sustained release. In vitrostudies confirmed a synchronized yet distinct profile: rapid AA diffusion and gradual LY release. XRD analysis confirmed both nutrients were stably dispersed in an amorphous state.

This study demonstrates that bioactive polysaccharides (CS/HA) are not mere additives but key functional materials actively controlling the rheological properties and microstructure of the O/W emulsion. Adjusting CS concentration alone allowed stability, mechanical strength and release rate to be programmed from initial burst to sustained. This approach presents high potential as a next-generation personalized nutrition delivery system, realizing the "Patch-Food" concept.

This poster qualifies for consideration for the Elsevier Competition