pH and glucose dual-responsive injectable hydrogels were prepared through the cross-linking of Schiff's base and phenylboronate ester using phenylboronic-modified chitosan, poly(vinyl alcohol) and benzaldehyde-capped poly(ethylene glycol). Protein drugs and live cells could be incorporated into the hydrogels during the in situ cross-linking, displaying sustained and pH/glucose-triggered drug release from the hydrogels and cell viability and proliferation in the three-dimensional hydrogel matrix as well. Hence, the hydrogels with insulin and fibroblasts were considered as bioactive dressings for diabetic wound healing. A streptozotocin-induced diabetic rat model was used to evaluate the efficacy of hydrogel dressings in wound repair. The results revealed that the incorporation of insulin and L929 in the hydrogels could promote neovascularization and collagen deposition and enhance the wound-healing process of diabetic wounds. Thus, the drug- and cell-loaded hydrogels have promising potential in wound healing as a medicated system for various therapeutic proteins and live cells.

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Scaffolds are an important aspect of the tissue engineering approach to tissue regeneration. This study shows that it is possible to manufacture scaffolds from type I collagen with or without hydroxyapatite (HA) by critical point drying. The mean pore sizes of the scaffolds can be altered from 44 to 135 microm depending on the precise processing conditions. Such pore sizes span the range that is likely to be required for specific cells. The mechanical properties of the scaffolds have been measured and behave as expected of foam structures. The degradation rate of the scaffolds by collagenase is independent of pore size. Dehydrothermal treatment (DHT), a common method of physically crosslinking collagen, was found to denature the collagen at a temperature of 120 degrees C resulting in a decrease in the scaffold's resistance to collagenase. Hybrid scaffold structures have also been manufactured, which have the potential to be used in the generation of multi-tissue interfaces. Microchannels are neatly incorporated via an indirect solid freeform fabrication (SFF) process, which could aid in reducing the different constraints commonly observed with other scaffolds.

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