Fig. 3

Formulation of hydrogel-drug matrix. The most routinely followed strategy for drug delivery from the hydrogel matrix is physical or chemical interactions. In physical interactions, the affinity between the gel and drug is often charge based. If the gel matrix is having more amino functional groups it could be useful for the delayed release of anionic drugs. Simply, the polymers can have significant effect on prolonged release of drugs of opposite charge. As opposed to physical interaction, drug is permanently linked to hydrogel matrix via covalent crosslinks. This kind of binding could be achieved with other methods like UV irradiation and redox-responsive supramolecular assembly