Fig. 2.

Structural diagrams of PLGA, PEGDA, NIPAM and polysaccharides. AChemical structure of the poly (D,L – lactide-co-glycolide) (PLGA) co-polymer. Reproduced with permission from Ref. [183]. Copyright 2019, Frontiers. B Structural diagram of NIPAM. Reproduced with permission from Ref. [125]. Copyright 2015, Springer. C Repeat unit of PEGDA (n ​= ​43) used in this study. Blue and pink regions represent the PEG segment and the acrylate cross-linker,respectively. Reproduced with permission from Ref. [118]. Copyright 2019, American Chemical Society. D Structural formula diagram of polysaccharides. Reproduced with permission from Ref. [128]. Copyright 2018, Elsevier. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)