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3,4-Dihydroxybenzaldehyde, a derivative of catechol and an agent with an extensive pharmacological and biological activities, was used to modify collagen and prepared hydrogels. The aldehyde group of 3,4-dihydroxybenzaldehyde interacted with the ɛ-amino group of collagen, and then the catechol group of 3,4-dihydroxybenzaldehyde was oxidized and self-polymerized. The chemical network formed due to the cross-linking bridges of polymerized catechol groups among collagen molecules, resulting in the transformation from solution to hydrogel. The results of the Fourier-transform infrared measurement indicated that the triple helix structure of collagen was integrated after cross-linking. The appearance of hydrogels changed from golden to dark brown with the increasing 3,4-dihydroxybenzaldehyde dose. When the weight ratio of 3,4-dihydroxybenzaldehyde and collagen increased from 0 to 2:1, the thermal denaturation temperature of collagen increased from 40.2 to 77.6℃ while the elastic modulus of collagen increased from 13.6 to 1061.4 Pa. The addition of 3,4-dihydroxybenzaldehyde also caused more compact morphologies and a dramatic enhancement in the enzymatic resistance of hydrogels. Moreover, the results of cell proliferation assay demonstrated the favorable biocompatibility of collagen hydrogels with 3,4-dihydroxybenzaldehyde. These promising data indicate that the novel hydrogels had significant potential for applications. [ABSTRACT FROM AUTHOR]

Free radicals and inflammation in the skin suffering from trauma cause oxidative damage and delayed healing, leading to adverse wound conditions. To adequately investigate the effects of free radicals and controlled immunogenicity for wound healing, we propose a tofu-based hybrid hydrogel with antioxidant and low immunogenicity properties that can be used for wound healing. Tofu, a food source material, was introduced for the first time into gelatin methacryloyl (GelMA) hydrogels by the photo-crosslinking method. The results demonstrated that the incorporation of tofu influenced the pores, swelling, water vapor transmission and compressive properties of hydrogels greatly. The antioxidant activities of hydrogels had been enhanced with increasing rations of tofu, and the fibroblast culture showed good proliferation on the hybrid hydrogels, as well as slight immunogenicity, thereby inducing the M2 differentiation of macrophages. Further, a full-thickness skin wound model was created to study the healing effect of hybrid hydrogels. In vivo results confirmed that the antioxidant activity and slight immunological stimulation properties of tofu hydrogels could accelerate the wound healing rate and improve the skin tissue regeneration effect. The present study validates that the tofu-based hybrid hydrogels have multiple bioactivities and could be potential antioxidant and immunoregulation hydrogels in wound healing applications.

Designing stimuli responsive, controllable and biocompatible multifunctional nanoparticles is an important progress in the current quest for drug delivery systems. Herein, we devoted to developing a β-cyclodextrin (β-CD) based drug delivery nanoparticles (NPs) that release Bovine serum albumin (BSA) via glucose-responsive gate. The design involves synthesis of sodium alginate with β-CD modified (Alg-β-CD) and methoxypolyethylene glycol (mPEG-Fc) containing ferrocene (Fc) uncharged end-capping. When α-cyclodextrin (α-CD) was added with these two segments, the stable non-covalent supramolecular structure of Alg-β-CD/mPEG-Fc/α-CD can be self-assembled into NPs in aqueous solution. BSA loaded Alg-β-CD/mPEG-Fc/α-CD also has been prepared. Interestingly, these supramolecular Alg-β-CD/mPEG-Fc/α-CD/BSA NPs showed uniform sphere structure and constant BSA loading content. Also, this new kind of NPs can disassemble in the present of hydrogen peroxide (H 2 O 2 ). Since glucose oxidase (GOD) can oxidize glucose and produce H 2 O 2 , so this kind of polymeric NPs can also have glucose responsive behavior in the GOD containing environment. Developed functional Alg-β-CD/mPEG-Fc/α-CD might be a promising drug delivery strategy for diabetes or immunotherapy with more efficiency.