**2. Stimuli-responsive microgels**

Stimuli-responsive properties can be incorporated into gels. Microgels may respond to a number of stimuli like pH, ionic strength, specific ions, external fields, and temperature [14–17]. Such DDSs are designed whether to target tissues, to reach specific intracellular locations, or to promote drug release [18]. Brief overview of the types of stimuli-responsive microgels is given below.
