Postoperative adhesion is a serious complication that can further lead to morbidity and/or mortality. Polymer anti-adhesion barrier material provides an effective precaution to reduce the probability of postoperative adhesion. Clinical application requires these materials to be easily handled, biocompatible, biodegradable, and most importantly tissue adherent to provide target sites with reliable isolation. However, currently there is nearly no polymer barrier material that can fully satisfy these requirements. In this study, based on the photoinduced imine-crosslinking (PIC) reaction, we had developed a photo-crosslinking hydrogel (CNG hydrogel) that composed of o-nitrobenzyl alcohol (NB) modified carboxymethyl cellulose (CMC-NB) and glycol chitosan (GC) as an anti-adhesion barrier material. Under light irradiation, CMC-NB generated aldehyde groups which subsequently reacted with amino groups distributed on GC or tissue surface to form a hydrogel barrier that covalently attached to tissue surface. Rheological analysis demonstrated that CNG hydrogel (30 mg/mL polymer content) could be formed in 30 s upon light irradiation. Tissue adhesive tests showed that the tissue adhesive strength of CNG hydrogel (30 mg/mL) was about 8.32 kPa–24.65 kPa which increased with increasing CMC-NB content in CNG hydrogel. Toxicity evaluation by L929 cells demonstrated that CNG hydrogel was cytocompatible. Furthermore, sidewall defect-cecum abrasion model of rat was employed to evaluate the postoperative anti-adhesion efficacy of CNG hydrogel. And a significantly reduction of tissue adhesion (20% samples with low score adhesion) was found in CNG hydrogel treated group, compared with control group (100% samples with high score adhesion). In addition, CNG hydrogel could be degraded in nearly 14 days and showed no side effect on wound healing. These findings indicated that CNG hydrogel can effectively expanded the clinical treatments of postoperative tissue adhesion.Statement of SignificanceIn this study, a tissue adhesive photo-crosslinking hydrogel (CNG) was developed based on photo-induced imine crosslinking reaction (PIC) for postoperative anti-adhesion. CNG hydrogel showed the features of easy and convenient operation, fast and controllable gelation, suitable gel strength, good biocompatibility, and most importantly strong tissue adhesiveness. Therefore, it shows very high performance to prevent postoperative tissue adhesion. Overall, our study provides a more suitable hydrogel barrier material that can overcome the shortcomings of current barriers for clinical postoperative anti-adhesion.Download high-res image (118KB)Download full-size image

An extrudable hydrogel with a tunable gelation time under physiological pH ranges based on the phase separation of gelatin and oxidized dextran was demonstrated. We envision that the easy handing properties of this hydrogel combined with thermosensitive physical gelation and postponed chemical reinforcing will provide a platform for 3D bioprinting applications.

The regeneration of articular cartilage, which scarcely shows innate self-healing ability, is a great challenge in clinical treatment. Stem cell-derived exosomes (SC-Exos), an important type of extracellular nanovesicle, exhibit great potential for cartilage regeneration to replace stem cell-based therapy. Cartilage regeneration often takes a relatively long time and there is currently no effective administration method to durably retain exosomes at cartilage defect sites to effectively exert their reparative effect. Therefore, in this study, we exploited a photoinduced imine crosslinking hydrogel glue, which presents excellent operation ability, biocompatibility and most importantly, cartilage-integration, as an exosome scaffold to prepare an acellular tissue patch (EHG) for cartilage regeneration. It was found that EHG can retain SC-Exos and positively regulate both chondrocytes and hBMSCs in vitro. Furthermore, EHG can integrate with native cartilage matrix and promote cell deposition at cartilage defect sites, finally resulting in the promotion of cartilage defect repair. The EHG tissue patch therefore provides a novel, cell-free scaffold material for wound repair.

In situ forming redox responsive nanoparticles have been developed based on amphiphilic copolymers-phototriggered disulfide-cross-link macromolecules (PDCM). Upon 405 nm light irradiation, the macrocyclic thiol caged coumarin phototrigger in PDCM can release free thiols, and these free thiols subsequently realize in situ disulfide cross-link via reacting with a pyridyl disulfide group inside the PDCM assembled nanoparticles. The phototriggered disulfide-cross-link strategy can be conducted rapidly, conveniently, and cleanly without adding any cross-linkers or catalysts. Via changing irradiation condition, nanoparticles with different cross-link densities can be formed. These nanoparticles can encapsulate hydrophobic guest molecules with good stability and achieve redox-triggered release under GSH reduction. Intracellular experiments show that these nanoparticles can be used as promising drug carriers.