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. Author manuscript; available in PMC: 2018 Apr 13.
Published in final edited form as: Nat Rev Mater. 2016 Oct 18;1(12):16071. doi: 10.1038/natrevmats.2016.71

Figure 2. Macroscopic design determines the delivery route.

Figure 2

a| Macroscopic hydrogels are used for transepithelial delivery and placement inside the body. Injectable macroscopic hydrogels that can be delivered via syringe-needle injection include (b) in situ-gelling hydrogels such as a hydrogel formed with tetrazine-norbornene chemistry, (c) shear-thinning hydrogels such as alginate hydrogels cross-linked with multivalent ions and (d) macroporous hydrogels that can undergo reversible dramatic volumetric change. In addition to transepithelial and local injection, microgels (e) are suitable for oral, pulmonary and intrabony delivery and nanogels (f) are suitable for systemic administration of drugs.