Table 1.
Common used gatekeepers are summarized in the below form.
| Gatekeeper | Stimuli | Trigger | Modal drug | Ref. |
|---|---|---|---|---|
| Carbon dots | Redox | GSH | DOX | (Zhang et al., 2016b) |
| ZnO quantum dots | pH | Acid | Mitoxantrone | (Huang et al., 2016) |
| Polyaramide precursors | pH | Acid | Ibuprofen | (Sánchez-Sánchez et al., 2015) |
| Carbon dots | pH | Acid | DOX | (Wang et al., 2015a) |
| Poly(N-isopropyl acrylamide) | Temperature | Temperature | Ibuprofen | (Zhu et al., 2011) |
| Manganese oxide | pH/HIFU | Acid/Ultrasound | DOX | (Zhang et al., 2015b) |
| Polyacrylic acid | pH/Redox | Acid/GSH | DOX | (Zhang et al., 2016a) |
| Hyaluronic acid | Redox/Enzyme | Reducing agent /Hyaluronidase | DOX | (Zhou et al., 2015) |
| Hyaluronic acid | pH/ Enzyme | Acid/Hyaluronidase | DOX/Verapamil | (Wan et al., 2016) |
| Copper sulfide (CuS) | pH/Temperature/NIR | Acid/Temperature/NIR light | DOX | (Zhang et al., 2015a) |