Synergistic effect of Mn-Si-COS on wound immune microenvironment by inhibiting excessive skin fibrosis mediated with ROS/TGF-ß1/Smad7 signal.

Excessive oxidative stress and inflammation often impede wound healing and ultimately lead to excessive skin fibrosis formation. It was known that the structural properties of biomaterials can affect the healing and immune response of surrounding tissues. In this work, a composite structure of Mn-Si-chitooligosaccharides (COS) was designed (COS@Mn-MSN) and the ability of regulating wound microenvironment for inhibiting skin fibrosis was investigated. In order to reduce the negative effects of Mn, the nano-level Mn was doped into MSN to minimize its content. The results show that Mn in COS@Mn-MSN showed significant ability of scavenging excess intracellular ROS within 1 d. The Si released from COS@Mn-MSN can shift M2 macrophage polarization in the later stage (1-3 d), showing anti-inflammatory effect. Macrophage (RAW264.7) were activated alternatively by COS released from COS@Mn-MSN, with upregulated expression of anti-inflammatory factors (IL-10 and CD206) and downregulated expression of pro-inflammatory factors (TNF-α, CD80, and IL-1ß) in the whole time. The expression of fibrosis associated factor TGF-ß1 and CD26 in fibroblast cells (L929) were inhibited by COS and Si. Besides, the inflammatory microenvironment mediated by COS@Mn-MSN downregulated Smad-7 gene expression and upregulated Col-1α gene expression. With the function of reducing oxidative stress (0-1 d), the TGF-ß1 inhibition (1-3 d) and anti-inflammatory effects (0-3 d), COS@Mn-MSN could inhibit excessive skin fibrosis formation mediated with ROS/TGF-ß1/Smad7 signal. Therefore, the prepared COS@Mn-MSN shows great potential to active scarless wound therapy.

High-Efficiency Near-Infrared Light Responsive Antibacterial System for Synergistic Ablation of Bacteria and Biofilm.

Bacterial infection is seriously threatening human health, and the design of high-efficiency and good biocompatibility antibacterial agents is an urgent problem to be solved. However, with the emergence of drug-resistant bacteria, the existing antibacterial agents have low killing efficiency, and the formation of biofilms has further weakened the therapeutic effect. Herein, we constructed an efficient antibacterial system mediated by near-infrared light for synergistic antibacterial and biofilm dissipation. Specifically, the ZnO/Ti3C2Tx with heterojunction was synthesized by hydrothermal growth of ZnO on the surface of lamellar Ti3C2Tx-MXene. The prepared ZnO/Ti3C2Tx had better photothermal ability than ZnO and Ti3C2Tx, respectively. The local thermal effect can not only destroy the integrity of the bacterial membrane but also promote the release of Zn2+ ions and further improve the antibacterial performance. ZnO/Ti3C2Tx achieved a 100% sterilization rate (better than either ZnO or Ti3C2Tx) at 150 µg mL-1. The biofilm dissipation experiment further proved its excellent biofilm ablation effect. More importantly, the results of in vitro cell culture and animal experiments have demonstrated its good biological safety. In summary, this new type of nanomaterial shows strong local chemical photothermal sterilization ability and has great potential to replace traditional antibacterial agents.

Blood compatibility evaluations of two-dimensional Ti3C2Txnanosheets.

Two-dimensional nanomaterial Ti3C2Txis a novel biomaterial used for medical apparatus. For its application, biosafety serves as a prerequisite for their usein vivo. So far, no research has systematically reported how Ti3C2Txinteracts with various components in the blood. In this work, we evaluated the hemocompatibility of Ti3C2Txnanosheets which we prepared by HF etching. Effects of the concentration and size of Ti3C2Txon the morphology and hemolysis rate of human red blood cells (RBCs), the structure and conformation of plasma proteins, the complement activation, as well asin vitroblood coagulation were studied. In general, Ti3C2Txtakes on good blood compatibility, but in the case of high concentration (>30 µg ml-1) and 'small size' (about 100 nm), it led to the rupture of RBCs membrane and a higher rate of hemolysis. Meanwhile, platelets and complement were inclined to be activated with the increased concentration, accompanying the changed configuration of plasma proteins dependent on concentration. Surprisingly, the presence of Ti3C2Txdid not significantly disrupt the coagulation.In vitrocell culture, the results prove that when the Ti3C2Txconcentration is as high as 60 µg ml-1and still has good biological safety. By establishing a fuzzy mathematical model, it was proved that the hemocompatibility of Ti3C2Txis more concentration-dependent than size-dependent, and the hemolysis rate is the most sensitive to the size and concentration of the Ti3C2Tx. These findings provide insight into the potential use of Ti3C2Txas biofriendly nanocontainers for biomaterialsin vivo.

Facile Polyphenol-Europium Assembly Enabled Functional Poly(l-Lactic Acid) Nanofiber Mats with Enhanced Antioxidation and Angiogenesis for Accelerated Wound Healing.

Burns, trauma, surgery and chronic diabetic ulcers are the most common reasons causing skin wounds in clinic. Thus, developing a functional wound dressing has been an imperative issue. Herein, functional wound dressing (poly(l-lactic acid) PLLA-((tanic acid (TA)/europium (Eu))n ) is fabricated through a facile polyphenol-europium ion assembly to ameliorate wound microenvironment via scavenging excessive reactive oxygen species (ROS) and promoting angiogenesis. The physicochemical characterization indicates that the multicycle assembled TA/Eu is uniformly deposited on PLLA-(TA/Eu)n nanofiber mats surface. In vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant tests display good antioxidant ability by scavenging more than 75% ROS, and significantly increasing the antioxidant enzyme levels in vivo. Cytocompatibility experiments illustrate that PLLA-(TA/Eu)n nanofiber mats can promote the adhesion and proliferation of human umbilical vein endothelial cells (HUVECs) and L929 cells. Meanwhile, real-time quantitative polymerase chain reaction (PCR) (RT-qPCR) and western blot assays illustrate that it can stimulate proangiogenesis by elevating the expression of angiogenesis-related genes and proteins. In vivo Sprague-Dawley (SD) rats experiments indicate that PLLA-(TA/Eu)n nanofiber mats can significantly promote wound healing by improving both angiogenesis and antioxidant activity. Taken together, the functional PLLA-(TA/Eu)n nanofiber mats can offer significant promise as wound dressing for accelerated wound healing.

Construction of biological factor-coated stent and its effect on promoting endothelialization.

Recently, just taking endothelialization of stent as an interventional treatment of aneurysms is unsatisfactory. This treatment also has impacts the occlusion rate of the aneurysm. In accordance with that, the authors aims to construct a novel biological factor-coated stent with dual biological effects of anticoagulation and endothelialization for the improvement of the occlusion rate of aneurysms and reduction of the risk for treatment of aneurysm with intravascular interventional therapy. The Ni-Ti alloy sheets loaded with VEGF and anti-CD34 antibody were put into use for stimulating the construction of the biological factor-coated stents, for the Ni-Ti alloy sheets could help improve the proliferation of endothelial cell (EC), recognize effectively and adhere to endothelial progenitor cell (EPC). Blood compatibility characterization methods (water contact angle, platelet activation test, clotting time evaluation and protein adsorption test) were applied for study the influence of the interaction between the Ni-Ti alloy sheets and blood. Cell experiments (HUVEC proliferation experiment, migration experiment and EPC capture experiment) were resorted to investigate the ability of the sheets to promote the proliferation of HUVEC and to capture EPCs. With the mature of the construction technology, the Enterprise stent with the biological factors were optimized accordingly, the biological function of that were verified by cell experiments. Studies showed that Ni-Ti alloy sheets and enterprise stents can successfully load with VEGF and anti-CD34 antibody. The below achievements can be realized including a better blood compatibility and effects of the constructed sheets and enterprise stents on promoting HUVEC proliferation and adhesion of EPC. It was meaningful of conversion to clinical application to improve the cure rate of the aneurysm and the safety of the intravascular treatment.

Surface Modification of Reduced Graphene Oxide Beads: Integrating Efficient Endotoxin Adsorption and Improved Blood Compatibility.

As a pathogenic toxin, endotoxins are the culprit for endotoxemia and can be generally removed from the blood by hemoperfusion. Reduced graphene oxide (rGO) is a promising endotoxin sorbent for hemoperfusion owing to its excellent adsorption capacity, but it has the side effect of nonspecific adsorption and low blood compatibility. Polymyxin B (PMB) acts as an organic affinity ligand that can specifically bind endotoxins. As a natural anticoagulant, heparin (Hep) can reduce the risk of coagulation and improve the blood compatibility of materials. Herein, an rGO bead adsorbent was prepared by coupling with PMB and Hep and used for endotoxin adsorption; in this, polydopamine (pDA) served as an active coating for immobilization of PMB and further coupling with Hep. The physicochemical characteristics indicated that PMB and Hep were successfully immobilized on rGO beads with a hierarchical pore structure. PMB endowed rGO beads with higher adsorption capacity (143.84 ± 3.28 EU/mg) and good adsorption selectivity for endotoxins. Hep significantly improved the blood compatibility of rGO beads. These modified rGO beads also achieved good adsorption capacity and adsorption selectivity for endotoxins in plasma, serum, or blood. Therefore, rGO/pDA/PMB/Hep beads are potential adsorbents for endotoxins in hemoperfusion.

Impacts of chitosan oligosaccharide (COS) on angiogenic activities.

It has been proved that chitosan oligosaccharide (COS) has a more favorable therapeutic applications such as wound healing and anti-tumor treatment, and can affect angiogenesis. For better understanding the effect of COS on angiogenic activities at cellular level, COS with different concentration and degree of polymerization (DP) were used to culture human umbilical vein endothelial cells (HUVECs) in this work. Cell proliferation activity, cell morphology, cell migration and angiogenesis associated factor expression of HUVECs were evaluated. The results indicated that COS at a high concentration of 400 µg/mL (COS(400)) and DP of 6 (Chitinhexaose Hydrochloride, COS6) had inhibitory effect on angiogenic activities of HUVECs. Specifically, COS(400) and COS6 inhibited cell proliferation activity, cell migration, and vascular endothelial cell growth factor (VEGF) expression of HUVECs. While COS at a low concentration (<400 µg/mL) and suitable polymerization degrees (DP < 6) had little significant effect on cell proliferation, migration, and VEGF expression of HUVECs, showing dose-dependent effect. These findings provided insight for the potential use of COS, for broadening its future applications in biomedical fields and functional materials area. It also helped guide the design and synthesis of chitosan-based materials as an angiogenesis inhibitor for anti-angiogenic therapy.

Sulfated chitosan coated polylactide membrane enhanced osteogenic and vascularization differentiation in MC3T3-E1s and HUVECs co-cultures system.

This study aimed to compare the effects of the two type chitosan derivatives, sulfated chitosan (SCS) and phosphorylated chitosan (PCS), coated on poly(d,l-lactide) (PDLLA) membrane via polydopamine, respectively, on vascularization and osteogenesis in vitro. Mouse preosteoblast cells (MC3T3-E1s) and human umbilical vein endothelial cells (HUVECs) were used as co-cultures system. The effects of two type membranes on calcium deposition, alkaline phosphatase (ALP) activity, vascularization related factors nitric oxide (NO) and angiogenic growth factor vascular endothelial growth factor (VEGF) were assessed. The changes of osteogenic and angiogenic related gene, and protein expression were evaluated too. In fact, SCS modified PDLLA membrane had the highest related gene and protein expression than other PDLLA membranes. Our results demonstrated that the SCS maybe a promising matrix for bone regeneration by co-cultures of ECs and OCs than PCS.

Different influence of sulfated chitosan with different sulfonic acid group sites on HUVECs behaviors.

The vascularization within the scaffold is still a significant challenge in tissue engineering applications. Sulfated chitosan (SCS) as an amazing substance have been used in tissue engineering to stimulate angiogenesis. However, it is not clear whether they have difference in the ability to promote vascularization of SCS with different sulfonic acid group sites. The aim of this study was to evaluate human umbilical vein endothelial cells (HUVECs) viability and differentiation in vitro, affected by three types of sulfated chitosan' i.e. 2-N-6-O-sulfated chitosan (2,6-SCS), 3'6-O-sulfated chitosan (3,6-SCS) and 6-O-sulfated chitosan (6-SCS). The results are showed that all the SCS possesses excellent biological properties to promote HUVECs viability and proliferation. Especially, 2,6-SCS promotes desirable intracellular nitric oxide secretion and capillary tube formation. Meanwhile, 2,6-SCS up-regulate the related gene and protein expression compared with other sulfonic acid group sites SCS and heparin. Therefore, 2,6-SCS is a promising substitute material for angiogenesis and as aqueous formulation can be employed to fabrication functionalization scaffold surface with promoted angiogenesis.

Tannic acid/CaII anchored on the surface of chitin nanofiber sponge by layer-by-layer deposition: Integrating effective antibacterial and hemostatic performance.

Massive blood loss and bacterial infection are major challenges for global public health. However, traditional wound dressings cannot fully meet the current clinical needs in controlling bleeding and avoiding infection. In this study, we prepared a chitin nanofiber suspension by green mechanical grinding and homogenizing, which could be used for developing a porous chitin nanofiber sponge by freeze drying. Then tannic acid/CaII was anchored on the surface of chitin nanofiber sponge by layer-by-layer deposition based on the coordination complex of tannic acid and Ca2+. These porous chitin nanofiber sponges with meso-macroporous structure could accelerate platelet aggregation for hemostasis. Hemostasis tests also demonstrated that the Ca2+ and TA in the TA/CaII coating on chitin nanofiber sponge could accelerate platelet activity and shorten the hemostatic time both in vitro and in vivo. Besides, the TA in the TA/CaII coating enhanced the antibacterial properties of the sponge, which depended the content of TA/CaII. Based on these results, it could be inferred that the chitin nanofiber sponges anchored TA/CaII coating had rapid hemostatic and antibacterial properties, which would have great potential for designing hemostatic product in clinical application.

Near-Infrared Light-Steered Graphene Aerogel Micromotor with High Speed and Precise Navigation for Active Transport and Microassembly.

Fuel-free light-driven micromotors have attracted increasing attention since the advantages of reversible, noninvasive, and remote maneuver are on demand with excellent spatial and temporal resolution. However, they suffer from a challenging bottleneck of the rather modest motion speed, which hinders their applications, needing to overcome the water flow movement in environmental water. Herein, we demonstrate a near-infrared (NIR) light-steered, precise navigation-controlled micromotor based on a reduced graphene oxide aerogel microsphere (RGOAM), which possesses an isotropic structure and is easily prepared by a one-step electrospray approach other than conventional light-propelled micromotors with the Janus structure. Benefiting from the ultralight weight of the aerogel and lesser fluid resistance on the water surface, the RGOAM motors show a higher motion speed (up to 17.60 mm/s) than that in the published literature, letting it overcome counterflow. Taking advantage of the photothermal conversion capacity of the RGOAM under an asymmetric light field, it is capable of moving both on the water driven by the Marangoni effect and under the water via light-manipulated density change. The motion direction and speed on water as well as the "start/stop" state can be precisely steered by NIR light even in a complicated maze. Due to its strong adsorption and loading capacity, the RGOAM can be applied for active loading-transport-release of dyes on demand as well as micropart assembling and shaping. Our work provides a strategy to achieve high speed, precise navigation control, and functional extensibility simultaneously for micromotors, which may offer considerable promise for the broad biomedical and environmental applications.

Macrophage Polarization Mediated by Chitooligosaccharide (COS) and Associated Osteogenic and Angiogenic Activities.

The host response to implanted biomaterials can influence the functionality of the materials and modulate the tissue repair and remolding. Macrophages, key cells in the host response to biomaterials, can be polarized into different phenotypes, which are important in regenerative medicine. The objective of this study was to evaluate the effect of chitooligosaccharide (COS) on the modulation of macrophage (RAW 264.7) polarization and the associated osteogenic and angiogenic activities. The results demonstrate that COS can shift the macrophage response to an alternatively activated reparative response, which can then upregulate the expression of anti-inflammatory cytokines. COS can also create an immune-modulated microenvironment, with osteogenesis- and angiogenesis-related proteins and a biological process that further influences the osteogenic/angiogenic differentiation and promotion of bone mesenchymal stem cells (BMSCs) and vascular activation of human umbilical vein endothelial cells (HUVECs). In this work, at a low concentration of 4 µg/mL [COS(4)] and suitable polymerization degree of 5 (chitopentaose hydrochloride, COS5) of COS, the associated effect on an alternatively activated reparative response and upregulation of anti-inflammatory cytokine expression was better than that of COS at other concentrations or polymerization degrees. The supernatant from a culture of RAW 264.7 stimulated by COS(4) and COS5 [conditioned medium S-COS(4) and S-COS5] contained more osteogenesis- and angiogenesis-related proteins like DKK-1, OPN, osteoactivin, vascular endothelial growth factor (VEGF) R1, epidermal growth factor (EGF), and insulin-like growth factor binding protein-5 (IGFBP-5) for regulation of osteogenesis/angiogenesis. Specifically, the alkaline phosphatase (ALP) activity and typical osteogenesis-related proteins of BMSCs were significantly influenced by the conditioned media of COS-stimulated macrophages [S-COS(4) and S-COS5]. Furthermore, the conditioned media affected HUVEC proliferation and migration for vascularization. Our results suggest that COS at a low concentration and suitable polymerization degrees has a beneficial effect on immunity modulation (an alternatively activated reparative response) and can modulate osteogenesis/angiogenesis processes for tissue regeneration without using any inductive agent.

Sulfonated chitosan and phosphorylated chitosan coated polylactide membrane by polydopamine-assisting for the growth and osteogenic differentiation of MC3T3-E1s.

In this study, a poly(d,l-lactide) (PDLLA) membrane was prepared by the solution casting method, then the surface of the membrane was modified by polydopamine (PDOPA) as a substrate, followed by adsorption of different chitosan derivative sulfonated chitosan (SCS) or/and phosphorylated chitosan (PCS) to obtain different functionalized membranes, and two kinds of chitosan derivatives characterized by FTIR, elemental analysis and zeta potential. And different membranes were evaluated through surface potential, hydrophilicity, surface morphology and chemical compositions. In vitro, the cell culture results showed that the membrane functionalized by chitosan derivative could promote the proliferation of MC3T3-E1s and enhance the osteogenic differentiation by up-regulating the expression level of osteogenic genes compared to the PDLLA and P1/PDOPA membranes. Especially, when the outermost layer was SCS, the effect of promoting cell proliferation was better than that of PCS. However, for osteogenic differentiation, PCS had better quantitative experimental results than SCS. Therefore, SCS has superiority in promoting proliferation than PCS, but PCS is opposite in promoting osteogenic differentiation for MC3T3-E1s. The results suggested that PCS and SCS have the potential value to be used as a functional modified materials applied in bone tissue engineering.

Fabrication of regular macro-mesoporous reduced graphene aerogel beads with ultra-high mechanical property for efficient bilirubin adsorption.

Three-dimensional graphene materials have been widely studied in many fields for their role as potential absorbent, especially for bilirubin adsorption. In this study, we developed a simple method to prepare reduced graphene aerogel beads as hemoperfusion materials for fast bilirubin adsorption. The graphene oxide (GO) aerogel beads were produced by self-assembly of GO nanosheet that cross-linked by Ca2+ previously in a coagulation bath, then it was reduced by ascorbic acid and lyophilized to yield the reduced graphene aerogel beads. The beads had a regular macroscopic spherical structure with a diameter of about 1.3-2 mm, where the macroporosity was about 10 µm and the mesoporosity was about 12 nm. The macro-mesoporous structure also gave the reduced graphene aerogel beads ultra-high mechanical strengths and high specific surface area, which were both important for hemoperfusion materials. Moreover, the fixed-bed column adsorption revealed that the reduced graphene aerogel beads manifested excellent bilirubin adsorption (649.512 mg/g) with a rapid adsorption equilibrium time (1.5 h) under the optimized conditions. Even in the bilirubin-enriched blood, the adsorption capacity of the beads could reach 367.14 mg/g. Furthermore, the aerogel beads had a low hemolysis ratio and improved anticoagulant property showing good blood compatibility. Hence, the spherical reduced graphene aerogel beads with millimeter-level size presented a good potential for clinical applications in hemoperfusion therapy.

Fabrication of chitosan/graphene oxide composite aerogel microspheres with high bilirubin removal performance.

Functional chitosan/graphene oxide (CS/GO) composite aerogel microspheres were fabricated via CO2 supercritical drying, which displayed excellent performance for bilirubin removal. The morphology and chemical structure of CS/GO composite aerogel microspheres were characterized, which illustrated a nanoporous structure with a maximum specific surface area of 174.69 m2/g, and a special pore size distribution at 20-40 nm, also a good mechanical property. Importantly, the composite aerogel microspheres (10% GO) revealed a large adsorption capacity (178.25 mg/g) for bilirubin within 2 h. Dynamic adsorption experiment illustrated that the aerogel microspheres adsorbed much more bilirubin with a shorter equilibrium time of about 30 min. Besides, the adsorption mechanism of bilirubin by the CS/GO composite aerogel microspheres was investigated through the relevant model fitting, including adsorption kinetics and adsorption isotherm, which illustrated that the mechanism included both physical and chemical processes, but chemical adsorption was dominated. Adsorption isotherm indicated that bilirubin adsorption by the microspheres was fitted well with Freundlich isotherm, which ascribed to multilayer adsorption. After five adsorption-desorption cycles, the adsorption capacity still maintains large adsorption capacity. In addition, the hemolysis rate and coagulation time tests presented the good blood compatibility for the adsorbents. Therefore, the CS/GO composite aerogel microspheres with rapid, high adsorption capacity and good blood compatibility might be promising for hyperbilirubinemia treatment.

Stress-relaxing double-network hydrogel for chondrogenic differentiation of stem cells.

The mechanical environment of extracellular matrix (ECM) plays an important role in adjusting the behaviors of cells. Natural ECM are highly viscoelastic materials with stress-relaxion behavior. Hydrogel is considered as a promising and attractive material for cell carrier, but they are typically elastic serving as synthetic ECM. Double-network (DN) hydrogel has an interpenetrating network of special structure combining the advantages of both rigid and ductile components, due to which the mechanical properties of the system can be very different from that of the single-network ones, and some special biological properties can be obtained. In this study, GG/PEGDA DN hydrogel was prepared by combining gellan gum (GG) with polyethylene glycol diacrylate (PEGDA), and then the influence of the two individual networks on the viscoelasticity of the system were investigated. Furthermore, the effects of viscoelasticity of GG/PEGDA DN hydrogel on the biological behavior of bone mesenchymal stem cells (BMSCs) were explored in vitro and in vivo. The results indicate that the spreading of BMSCs was closely related to the relaxation behavior of the hydrogels. GG/PEGDA DN hydrogel shows excellent mechanical and relaxation properties which provide a favorable physical environment for cell proliferation and spreading, and induce chondrogenic differentiation. Our study demonstrates that this DN hydrogel has bright prospects in the fields of cell carrier and cartilage tissue engineering.

Construction of blood compatible chitin/graphene oxide composite aerogel beads for the adsorption of bilirubin.

Excess bilirubin in blood can provoke hepatic damage and related malfunctions. Hereby we designed and constructed a novel bilirubin adsorbent, called chitin/graphene oxide (Ch/GO) composite aerogel beads, for efficient, fast and safe removal for bilirubin. The Ch/GO aerogel beads were prepared from chitin and GO in a NaOH/urea aqueous solution, followed dried by supercritical carbon dioxide. The morphology, structure and properties of the Ch/GO composite aerogel beads were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and compressive strength measurement. The results indicated that GO was successfully bound to chitin matrix with enhanced surface area, thermal stability and mechanical strength. The adsorption capacity of Ch/GO composite aerogel beads for bilirubin was examined by UV-vis spectrophotometry. Moreover, batch adsorption results revealed that the Ch/GO composite aerogel beads showed excellent bilirubin adsorption capacity (484.1 ± 16.9 mg/g) and short adsorption equilibrium time (0.5 h) under optimized condition. Furthermore, the Ch/GO aerogel beads exhibited a lower hemolysis property and improved anticoagulant property. Hence, this work provided a new strategy to develop a novel blood compatible bilirubin adsorbent, which presented good application potential for bilirubin adsorption.

Construction and characterization of an antibacterial/anticoagulant dual-functional surface based on poly l-lactic acid electrospun fibrous mats.

In this study, a poly l-lactic acid (PLLA) fibrous mat was prepared by electrospinning, followed by surface modification with polydopamine (PDA), based on its strong adhesion performance and self-polymerization of dopamine. The PDA coating on the fibrous mat surface provided a reaction platform for heparin via a Michael-type addition reaction and a reductive surface for Ag+ in situ formation of silver nanoparticles (AgNPs) in AgNO3 solution. The structure and chemical composition of the fibrous mats were determined by scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. All the results confirmed the successful immobilization of heparin and AgNPs on the PLLA fibrous mats. Thermogravimetric analysis (TGA) and energy dispersive X-ray spectrum (EDS) analysis were used to determine the content of AgNPs and their distribution on the fibrous mat surface. Water contact angle measurements showed the hydrophilic improvement after modification. The antibacterial investigation indicated that the fibrous mats could inhibit the growth of both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Protein adsorption, the hemolysis test, the coagulation test, complement activation, and platelet activation were used to confirm the compatibility with blood and the anticoagulation property of the fibrous mats. Finally, cell proliferation and live/dead assays, conducted with cultured fibroblasts on the fibrous mats, showed that the modified fibrous mat surface had good cell compatibility. This antibacterial/anticoagulant dual-functional surface, based on poly l-lactic acid electrospun fibrous mats, would have potential application in blood contacting materials.

Fabrication of chitin/graphene oxide composite sponges with higher bilirubin adsorption capacity.

Chitin/graphene oxide (Ch/GO) composite sponges had been synthesized in 11 wt% NaOH/4 wt% urea aqueous solution by a simple method. The structure, thermal stability and mechanical properties of the composite sponges were investigated by scanning electron microscopy, Fourier-transform infrared spectroscopy, wide-angle X-ray diffraction, thermogravimetric analysis, and compressive strength measurements. The results revealed that chitin and GO were mixed homogeneously. Interestingly, the composite sponges showed meso-macroporous structure, which played an important role in improving their adsorption properties. Besides, thermal stability and mechanical properties were significantly improved compared with pure chitin sponges. Taking advantages of these fantastic characteristics, the maximum adsorption capacity of composite sponges for bilirubin was up to 422.9 mg/g under the optimized condition, which was not only significantly higher than the adsorption capacities of pure chitin sponges, but also superior to those of many reported adsorbents for removal of bilirubin. Furthermore, blood compatibility evaluations confirmed that this blended sponges had negligible hemolysis and coagulation. Therefore, this work provided a potential possibility to offer Ch/GO composite sponges for removal of bilirubin.

Experimental Study on Effects of Adipose-Derived Stem Cell-Seeded Silk Fibroin Chitosan Film on Wound Healing of a Diabetic Rat Model.

BACKGROUND: Wound healing is a complex process that relies on growth factors and stimulation of angiogenesis. Tissue engineering materials composed of adipose-derived stem cells (ADSCs) and silk fibroin (SF)/chitosan (CS) may be able to solve this problem. The aim of this study was to investigate the wound-healing potential of ADSC-seeded SF/CS in streptozotocin-induced diabetic rats. MATERIALS AND METHODS: Thirty-six male Sprague-Dawley rats were purchased and randomly assigned into 3 groups: a control group (no graft), a group treated with SF/CS film graft, and a group treated with ADSC-seeded SF/CS graft. The number of animals in each group was 12. Diabetes was induced by an intraperitoneal injection of streptozotocin. A cutaneous wound was incised at the dorsal region of all the experimental animals. The ADSCs were labeled with CM-Dil fluorescent staining. Wound healing was assessed for all animal groups by observing the rate of wound closure and hematoxylin and eosin staining. The expression of epidermal growth factor, transforming growth factor-ß, and vascular endothelial growth factor at the wound sites was studied by enzyme-linked immunosorbent assay to evaluate the effect of growth factors secreted by ADSCs. The differentiation of ADSCs was analyzed by immunofluorescence staining. RESULTS: The ADSC-seeded SF/CS film treatment significantly increased the rates of wound closure in treated animals, and hence wound healing was drastically enhanced for ADSC-SF/CS treatment groups compared with control groups and SF/CS film treatment group. Histological observations showed the condition of wound healing. Enzyme-linked immunosorbent assay and immunofluorescence staining observations showed the secretion and differentiation of ADSCs, respectively. CONCLUSIONS: Our analyses clearly suggested that it is feasible and effective to enhance wound healing in a diabetic rat model with ADSC-seeded SF/CS film.