Chlorhexidine-loaded polysulfobetaine/keratin hydrogels with antioxidant and antibacterial activity for infected wound healing.

Multifunctional hydrogel dressings are promising for wound healing. In the study, chlorhexidine(CHX) loaded double network hydrogels were prepared by free radical polymerization of sulfobetaine and oxidative self-crosslinking of reduced keratin. The introduced keratin and CHX endowed hydrogels with cytocompatibility, antioxidant capability as well as enhanced antibacterial activity due to the antifouling property of polysulfobetaine. These hydrogels exhibited acidity, glutathione(GSH), and trypsin triple-responsive release behaviors, resulting in the accelerated release of CHX under wound microenvironments. Intriguingly, the freeze-drying hydrogels could be ground to powders and sprinkled on the irregular wound bed, followed by absorbing wound fluid to reform hydrogel in situ. These xerogel powders were more convenient for sterilization, formulation, and storage. Further, these xerogel powders could be rejected after being mixed with an appropriate amount of water. In vivo infected wound healing confirmed that the xerogel powder dressing significantly promoted collagen deposition and reduced inflammation, thereby accelerating the closure and regeneration of skin wounds. Taken together, these degradable xerogel powders have great potential applications for wound healing.

Biocompatible and photocrosslinkable poly(ethylene glycol)/keratin biocomposite hydrogels.

A biocompatible hydrogel is ideal for tissue engineering and regeneration. In this study, methacrylated keratin (KerMA) was synthesized for the first time and then blended with poly(ethylene glycol dimethacrylate) (PEGDMA) to form hydrogel through photocrosslinking. The chemical structure, gelation time, swelling behavior, hydrophilicity, cytotoxicity, and 3D printability of PEGDMA/KerMA hydrogels were characterized and exploited. The PEGDMA/KerMA hydrogels performed good cytocompatibility, providing potential applications for tissue engineering and regenerative medicine.

Antioxidant and multi-sensitive PNIPAAm/keratin double network gels for self-stripping wound dressing application.

Hydrogel is a potential wound dressing material due to its ability to maintain a humid environment, the strong absorptive capacity of exuded tissue fluid, and gas exchange function. Herein, poly(N-isopropyl acrylamide)/keratin double network (PNIPAAm/keratin DN) gels were fabricated through covalent and ionic double cross-linking strategy. The effects of PNIPAAm/keratin ratios on the morphology and swelling rate of gels were characterized. The DN gels could swell up from 2600% to 4600% in proportion to the keratin content, demonstrating their great ability to absorb tissue fluid. The gels possessed thermo-sensitiveness, imparting self-stripping property. Moreover, the antibacterial chlorhexidine acetate (CHX) was loaded into gels with a post-fabrication drug-loading strategy. The release behavior showed that CHX-loaded DN gels exhibited multiple responsive characteristics (temperature, pH, and ROS). Furthermore, the drug-loaded gels showed greater antibacterial activity than free CHX due to the sustained drug release effect. Meanwhile, the antioxidant efficiency of PNIPAAm/keratin DN gels was ca. 33.1%, while the PNIPAAm gel was just ca. 18.2%, indicating the strong oxidation resistance of DN gels. In the Sprague Dawley (SD) rat skin defect model, the hydrogel had better tissue regeneration ability than the commercial film. Taken together, the multifunctional PNIPAAm/keratin DN gels are potential candidates for clinical wound treatment.

Fabrication of PCL/keratin composite scaffolds for vascular tissue engineering with catalytic generation of nitric oxide potential.

Tissue-engineered vascular grafts (TEVGs) have been proposed as a promising approach to fulfill the need for small-diameter blood vessel substitutes. However, common failure caused by thrombosis and neointimal proliferation after implantation has restricted their use in the clinic. Herein, a NO-generating scaffold for vascular tissue engineering was developed by coelectrospinning poly(ε-caprolactone) (PCL) with keratin. The morphology and surface chemical composition were characterized via SEM, ATR-FTIR spectroscopy and XPS. The biocomposite scaffold selectively enhanced the adhesion and growth of endothelial cells (ECs) while suppressing the proliferation of smooth muscle cells (SMCs) in the presence of GSH and GSNO due to the catalytic generation of NO. In addition, these mats displayed excellent blood compatibility by prolonging the blood-clotting time. In summary, these NO-generating PCL/keratin scaffolds have potential applications in vascular tissue engineering with rapid endothelialization and reduced SMC proliferation.

Catalytic Generation of Nitric Oxide from Poly(ε-caprolactone)/Phosphobetainized Keratin Mats for a Vascular Tissue Engineering Scaffold.

Tissue-engineered vascular graft (TEVG) is a promising alternative to meet the clinical demand of organ shortages. Herein, human hair keratin was extracted by the reduction method, followed by modification with zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) through thiol-Michael addition to improve blood clotting nature. Then, phosphobetainized keratin (PK) was coelectrospun with poly(ε-caprolactone) (PCL) to afford PCL/PK mats with a ratio of 7:3. The surface morphology, chemical structure, and wettability of these mats were characterized. The biocomposite mats selectively enhanced adhesion, migration, and growth of endothelial cells (ECs) while suppressed proliferation of smooth muscle cells (SMCs) in the presence of glutathione (GSH) and GSNO due to the catalytic generation of NO. In addition, these mats exhibited good blood anticoagulant activity by reducing platelet adhesion, prolonging blood clotting time, and inhibiting hemolysis. Taken together, these NO-generating PCL/PK mats have potential applications as a scaffold for vascular tissue engineering with rapid endothelialization and reduced SMC proliferation.

Keratin-Poly(2-methacryloxyethyl phosphatidylcholine) Conjugate-Based Micelles as a Tumor Micro-Environment-Responsive Drug-Delivery System with Long Blood Circulation.

Drug-loaded micelles with long circulation time in blood and stimuli-responsiveness under the tumor micro-environment can significantly enhance therapeutic efficacy. In this report, human hair keratin was extracted with a reduction method and then conjugated with zwitterionic poly(2-methacryloxyethyl phosphatidylcholine, MPC) via thiol chain transfer polymerization (thiol CTP). Subsequently, keratin-polyMPC conjugates (KPC) were prepared into micelles and loaded with doxorubicin (DOX) by self-assembly. These micelles exhibited pH, glutathione (GSH), and enzyme triple-responsiveness as well as charge reversibility under the tumor micro-environment. In addition, these micelles showed high toxicity against A549 cells while low toxicity to normal cells. In vivo anticancer efficacy results revealed that these micelles showed better therapeutic efficiency than free DOX. Furthermore, these carriers exhibited prolonged circulation time, good stability, and no hemolysis in blood. Based on the results, these drug delivery systems of micelles were proper candidates as drug carriers.

Poly(ε-caprolactone)/keratin/heparin/VEGF biocomposite mats for vascular tissue engineering.

Vascular endothelial growth factor (VEGF) is an effective growth and angiogenic cytokine, which stimulates proliferation and survival of endothelial cells, and promotes angiogenesis and vascular permeability. Binding VEGF with heparin could protect it from rapid degradation, subsequently allowing it to be controlled release. Primarily, poly(ε-caprolactone) (PCL) and keratin were coelectrospun, followed by conjugating with heparin and subsequently binding VEGF. The loaded heparin and VEGF on these mats were quantified, respectively. The surface characteristics of mats were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The VEGF delivery results indicated these mats could sustainably release VEGF for 2 weeks. Cell viability assays suggested these mats were valid to accelerate human umbilical vein endothelial cells (HUVECs) proliferation, while inhibit human umbilical arterial smooth muscle cells (HUASMCs) growth under the combined actions of VEGF and heparin. The results tested by blood clotting times (APTT, PT, and TT), hemolysis, and platelet adhesion indicated the mats were blood compatible. To sum up, these biocomposite mats are ideal scaffolds for vascular tissue engineering.

Electrospun PCL/keratin/AuNPs mats with the catalytic generation of nitric oxide for potential of vascular tissue engineering.

Nitric oxide (NO)-generating materials are beneficial for vascular tissue engineering (VTE) scaffold because the produced NO would enhance endothelial cells viability while inhibit smooth muscle cell (SMC) proliferation and reduce platelet adhesion, resulting in ideal hemocompatibility and endothelialization. Herein, poly(ε-caprolactone) (PCL)/keratin biocomposite mats were first fabricated, followed by in situ gold (Au) nanoparticles loading to afford PCL/keratin/AuNPs mats. These mats were characterized using field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The PCL/keratin/AuNPs mats were demonstrated to be capable of catalyzing NO release in the mimicked blood microenvironments. The generated NO could enhance human umbilical vein endothelial cell growth and inhibit human umbilical arterial SMC viability. In addition, these mats maintained the antibacterial activity of Au nanoparticles with good blood compatibility. Taken together, these keratin-based composite mats have potential usage in the VTE. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3239-3247, 2018.

Heparinized PCL/keratin mats for vascular tissue engineering scaffold with potential of catalytic nitric oxide generation.

Heparins are capable of improving blood compatibility, enhancing HUVEC viability, while inhibiting HUASMC proliferation. Combination of biodegradable poly(ε-caprolactone) (PCL) with keratin and heparins would provide an anticoagulant and endothelialization supporting environment for vascular tissue engineering. Herein, PCL and keratin were first coelectrospun and then covalently conjugated with heparins. The resulting mats were surface-characterized by ATR-FTIR, SEM, WCA, and XPS. Cell viability data showed that the heparinized PCL/keratin mats could motivate the adhesion and growth of HUVEC, while inhibit HUASMC proliferation. In addition, these mats could prolong blood clotting time and reduce platelet adhesion as well as no erythrolysis. Interestingly, these mats could catalyze the NO donor in blood to release NO, which could enhance endothelial cell growth, while decrease smooth muscle cell proliferation and platelet adhesion. In summary, the heparinized mats would be a good candidate as a scaffold for vascular tissue engineering. This study is novel in that we prepared a type of heparinized tissue scaffold that could catalyze the NO donor to release NO to regulate endothelialization without angiogenesis and thrombus formation.