Multidimensional gradient hydrogel and its application in sustained release

We prepared two types of multidimensional gradient hydrogels by simple electrophoresis using spherical graphite electrode. To explore their application in controlled drug release, rhodamine B (RB) and sodium salicylate (SS) were used as oppositely charged drug models respectively to in situ loading into the hydrogels by electrostatic interaction with the charged components accordingly. In both cases, the model drugs and the charged components of the hydrogels were gradiently distributed with the drug concentration increased from the gel surface to the gel core. For the crosslinking gradient hydrogel prepared at 2 V, the network size near the gel surface is about 3 times that of the gel core, and the release rate is 0.85 times of that of the non-gradient hydrogel. For the polymer chain gradient hydrogel prepared at 2.5 V, the relative content of polymer chain near the core of the gel is 2.5 times that of the gel surface, and the release rate is 0.71 times of the non-gradient hydrogel.