Responsive drug delivery systems can be classified based on the type of stimulus they respond to:
1. pH-responsive systems: These systems exploit the pH differences between healthy and diseased tissues, such as the acidic environment of tumors or inflamed tissues, to trigger drug release. 2. Enzyme-responsive systems: These systems are designed to respond to specific enzymes that are overexpressed in certain diseases, such as proteases in cancer. 3. Temperature-responsive systems: These systems utilize materials that undergo phase transitions at specific temperatures, enabling drug release in response to localized heating. 4. Light-responsive systems: These systems use light-sensitive materials that release drugs upon exposure to specific wavelengths of light. 5. Magnetic-responsive systems: These systems incorporate magnetic nanoparticles that can be directed and heated using an external magnetic field to release drugs.
