Jiehua Li

Diabetic wounds are typified by hyperglycemia, hypoxia, chronic inflammation, and elevated oxidative stress, all of which collectively contribute to delayed and dysregulated healing. Inspired by the structural and functional attributes of native skin, we designed a dynamic bond-crosslinked, injectable, and in situ-forming polyurethane/hyaluronic acid-based hybrid hydrogel (PUS-OHABE). In this hydrogel, caffeic acid phenethyl ester (CAPE) was grafted onto aldehyde-modified hyaluronic acid (HA) chains through dynamic borate ester bonds. This CAPE-modified HA was then combined with a side-chain hydrazide (ADH)-modified waterborne polyurethane emulsion via Schiff base reactions to form a stable hydrogel network structure. The PUS-OHABE hydrogel exhibits good self-healing ability, stability, tissue adhesion, and hemostatic capacity. Additionally, it has a unique ability to dissociate borate ester bonds in the hyperglycemic wound microenvironment to responsively release CAPE, thereby conferring antioxidant and anti-inflammatory properties. In diabetic rat models, the PUS-OHABE hydrogel enabled rapid wound healing and re-epithelialization; meanwhile, it also promoted angiogenesis, hair follicle regeneration, and extracellular matrix remodeling, thus offering a promising strategy for the design of biomaterials targeting chronic wound healing.

The elegant hierarchical structures of biomacromolecules have promoted the pursuits of synthetic polymers with ordered monomer sequences and diverse topological architectures, which are in the initial stage. Here, a four-arm star-shaped segmented polyurethane (PU) with a controlled block sequence of amphiphilic seven-segment multifunctional arms containing a disulfide bond was prepared via a grafting-onto strategy, where the sequence-defined arms were synthesized by a diisocyanate-based liquid-phase iterative methodology and then conjugated onto four alkyne-functionalized pentaerythritol cores through click chemistry. The star-shaped PU can self-assemble into micelles in aqueous solution as the linear arm. Moreover, the four-arm star-shaped architecture endows self-assembled micelles with higher stability under various physiological conditions and enhanced redox-responsive performance, making them promising candidates for drug delivery. The experiments show that drug-loaded star-shaped PU micelles possess accelerated stimuli-responsive release profiles, optimized tissue distribution, and improved anticancer efficacy in vitro and in vivo in comparison with linear polymer micelles. This work demonstrates that advanced architectures of precise linear polymers hold tremendous potential for the structural regulation and performance adjustment of aggregation structures, opening the perspectives for the structural and functional design of next-generation materials.

Synthesis biomedical waterborne polyurethane with high strength retention and satisfactory water absorption by a solvent free method.

The physical and chemical properties of tissue engineering scaffolds have considerable effects on the inflammatory response at the implant site in soft tissue repair. The development of inflammation-modulating polymer scaffolds for soft tissue repair is attracting increasing attention. In this study, in order to regulate the inflammatory response at the implant site, a series of waterborne polyurethane (WPU) scaffolds with different properties were synthesized using polyethylene glycol (PEG), polycaprolactone (PCL) and poly (lactic acid)–glycolic acid copolymers (PLGAs) with three lactic acid/glycolic acid (LA/GA) ratios as the soft segments. Then, scaffolds were obtained using freeze-drying. The WPU scaffolds exhibited a porous cellular structure, high porosity, proper mechanical properties for repairing nerve tissue and an adjustable degradation rate. In vitro cellular experiments showed that the degradation solution possessed high biocompatibility. The in vitro inflammatory response of C57BL/6 mouse brain microglia (immortalized) (BV2) cells demonstrated that the LA/GA ratio of the PLGA in WPU scaffolds can regulate the external inflammatory response by altering the secretion of IL-10 and TNF-α. Even the IL-10/TNF-α of PU5050 (3.64) reached 69 times that of the control group (0.053). The results of the PC12 culture on the scaffolds showed that the scaffolds had positive effects on the growth, proliferation and differentiation of nerve cells and could even promote the formation of synapses. Overall, these scaffolds, particularly the PU5050, indeed prevent BV2 cells from differentiating into a pro-inflammatory M1 phenotype, which makes them promising candidates for reducing the inflammatory response and repairing nerve tissue. Furthermore, PU5050 had the best effect on preventing the transformation of BV2 cells into the pro-inflammatory M1 phenotype.

Biofilms are known to be difficult to eradicate and control, complicating human infections and marine biofouling. In this study, self-polishing and anti-fouling waterborne polyurethane coatings synthesized from gemini quaternary ammonium salts (GQAS), polyethylene glycol (PEG), and polycaprolactone diol (PCL) demonstrate excellent antibiofilm efficacy. Their anti-fouling and anti-biofilm performance was confirmed by a culture-based method in broth media, with the biofilm formation factor against Gram-positive (S. aureus) and Gram-negative bacterial strains (E. coli) for 2 days. The results indicate that polyurethane coatings have excellent anti-biofilm activity when the content of GQAS reached 8.5 wt% against S. aureus, and 15.8 wt% against E. coli. The resulting waterborne polyurethane coatings demonstrate both hydrolytic and enzymatic degradation, and the surface erosion enzymatic degradation mechanism enables them with good self-polishing capability. The extracts cyto-toxicity of these polyurethane coatings and degradation liquids was also systematically studied; they could be degraded to non-toxic or low toxic compositions. This study shows the possibility to achieve potent self-polishing and anti-biofilm efficacy by integrating antibacterial GQAS, PEG, and PCL into waterborne polyurethane coatings.