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. Author manuscript; available in PMC: 2020 May 18.
Published in final edited form as: Nat Biomed Eng. 2020 Feb 3;4(5):499–506. doi: 10.1038/s41551-019-0508-y

Fig. 1 |. Schematic of the glucose-responsive insulin delivery system using microneedle-array patches with glucose-responsive matrix.

Fig. 1 |

a, Schematic of the fabrication process of a glucose-responsive insulin patch from a silicone mould using an in situ photopolymerization strategy. b, Mechanism of glucose-triggered insulin release from GR-MNs. Upon exposure to a hyperglycaemic state, the increased negative charges resulting from the formation of the glucose-boronate complexes can weaken the electrostatic interaction between negatively charged insulin and polymers and induce the volume variation of polymeric matrix, promoting the quick release of insulin from the microneedles. Glucose levels of diabetic pigs can be effectively regulated by the administration of a glucose-responsive insulin patch. c, Characterization of the GR-MN. (i) Photograph of the GR-MN patch. (ii) Scanning electron microscopy image of the microneedle array. Scale bar, 500 μm. (iii) Microscopy (top) and fluorescence microscopy (bottom) images of the rhodamine B-labelled insulin (red)-loaded microneedle patch. Scale bar, 500μm.