2.4. Effect of Matrix Solution Concentration on Drug Diffusion

To observe the diffusion intuitively of drugs in MNs in matrix solution with different concentrations, rhodamine B with a distinct color was selected as the model drug [28]. The casting material was obtained by mixing 3% (wt) SA solution with rhodamine B (2 mg/mL). SA-MNs containing rhodamine B were prepared based on the methods described in Section 2.3. The patches containing rhodamine B were placed in the EP tube of the matrix solution containing Ca²⁺, and the dye diffusion state was observed visually after 0 h and 10 h. To make the diffusion phenomenon more practical, the TS-MNs encapsulating rhodamine B were applied, which was attained based on the preparation method in Section 2.2.