Design of an apoptotic cell-mimetic wound dressing using phosphoserine-chitosan hydrogels.

Inflammatory M1 macrophages create a hostile environment that impedes wound healing. Phosphoserine (PS) is a naturally occurring immunosuppressive molecule capable of polarizing macrophages from an inflammatory phenotype (M1) to an anti-inflammatory phenotype (M2). In this study, we designed, fabricated, and characterized PS-immobilized chitosan hydrogels as potential wound dressing materials.

Green tea catechin-grafted silk fibroin hydrogels with reactive oxygen species scavenging activity for wound healing applications.

Background: Overproduction of reactive oxygen species (ROS) is known to delay wound healing by causing oxidative tissue damage and inflammation. The green tea catechin, (-)-Epigallocatechin-3-O-gallate (EGCG), has drawn a great deal of interest due to its strong ROS scavenging and anti-inflammatory activities. In this study, we developed EGCG-grafted silk fibroin hydrogels as a potential wound dressing material.

Bioabsorbable Carboxymethyl Starch-Calcium Ionic Assembly Powder as a Hemostatic Agent.

In contrast to hemostatic fabrics, foams, and gels, hemostatic spray powders may be conveniently applied on narrow and complex bleeding sites. However, powdered hemostatic agents are easily desorbed from the bleeding surface because of blood flow, which seriously decreases their hemostatic function. In this study, the hemostatic performance of a bioabsorbable powder with decreased desorption was investigated.

Photodynamic Activity of Protoporphyrin IX-Immobilized Cellulose Monolith for Nerve Tissue Regeneration.

The development of nerve conduits with a three-dimensional porous structure has attracted great attention as they closely mimic the major features of the natural extracellular matrix of the nerve tissue. As low levels of reactive oxygen species (ROS) function as signaling molecules to promote cell proliferation and growth, this study aimed to fabricate protoporphyrin IX (PpIX)-immobilized cellulose (CEPP) monoliths as a means to both guide and stimulate nerve regeneration. CEPP monoliths can be fabricated via a simple thermally induced phase separation method and surface modification.

Guided Regeneration of Rabbit Calvarial Defects Using Silk Fibroin Nanofiber-Poly(glycolic acid) Hybrid Scaffolds.

Bone tissue engineering aims to regenerate defected bones by combining cells, scaffolds, and growth factors. In general, defected bone tissues are treated with barrier membranes or guiding scaffolds to achieve bone restoration. However, the growth rate of bone tissue is slower than that of adjacent soft tissue.

Shape-dependent antimicrobial activities of silver nanoparticles.

An important application of silver nanoparticles (Ag NPs) is their use as an antimicrobial and wound dressing material. The aim of this study is to investigate the morphological dependence on the antimicrobial activity and cellular response of Ag NPs. Ag NPs of various shapes were synthesized in an aqueous solution using a simple method.

Polypeptide Thermogel-Filled Silk Tube as a Bioactive Nerve Conduit.

To repair nerve damages, nerve conduits are clinically used. However, when the gap distance is greater than 3 cm, nerve damages remain difficult to repair using current empty nerve conduits. To improve the nerve conduit, a silk nerve conduit (diameter = 5 mm and length = 3 cm) filled with a hydrogel matrix was prepared by injecting a thermogelling aqueous poly(ethylene glycol)-poly(l-alanine) (PEG-PA) solution containing stem cells and neurotropic factors into a silk tube at 37 °C.

Surface modification of PHBV nanofiber mats for rapid cell cultivation and harvesting.

To maintain the original function of a specific tissue for therapeutic tissue engineering, an advanced cell culture surface for repeat cell proliferation is necessary. We designed a novel cell proliferation and rapid harvesting surface by combining nonwoven nanofiber mat and a thermo-responsive polymer. Nanofibrous poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) mats were fabricated by the electrospinning technique.

Preventing postoperative tissue adhesion using injectable carboxymethyl cellulose-pullulan hydrogels.

An injectable adhesive hydrogel composed of carboxymethyl cellulose (CMC) and pullulan is developed and evaluated as a postoperative anti-adhesion barrier. CMC was modified with tyramine to introduce crosslinking site via an EDC-NHS reaction. The in situ hydrogel was prepared by an enzyme-mediated reaction of tyramine-immobilized CMC with horseradish peroxidase (HRP) and hydrogen peroxide (HO).

Modification and optimization of electrospun gelatin sheets by electron beam irradiation for soft tissue engineering.

Background: Crosslinked gelatin nanofibers are one of the widely used scaffolds for soft tissue engineering. However, modifying the biodegradation rate of chemically crosslinked gelatin is necessary to facilitate cell migration and tissue regeneration. Here, we investigated the optimal electron beam (e-beam) irradiation doses with biodegradation behavior on changes in the molecular weight, morphology, pore structure, and cell proliferation profiles of electrospun nanofibrous gelatin sheets.

Silk fibroin/hydroxyapatite composite hydrogel induced by gamma-ray irradiation for bone tissue engineering.

Background: In this study, silk fibroin (SF) composite hydrogels containing hydroxyapatite (HAP) nanoparticles (NPs) for bone tissue engineering were fabricated using gamma-ray (γ-ray) irradiation treatment. During the irradiation, the HAP dispersed SF solution was changed to the chemically crosslinked SF hydrogel.

Methods: Distribution of HAP NPs in the SF hydrogel was examined by SEM imagery and energy dispersive X-ray spectrophotometry, and the crystalline structure of SF composite hydrogels was also confirmed by X-ray diffractometry.

Growth behavior of endothelial cells according to electrospun poly(D,L-lactic-co-glycolic acid) fiber diameter as a tissue engineering scaffold.

Investigating the effect of electrospun fiber diameter on endothelial cell proliferation provides an important guidance for the design of a fabric scaffold. In this study, we prepared biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) fibrous nonwoven mats with different fiber diameters ranged from 200 nm to 5 µm using the electrospinning technique. To control the fiber diameters of PLGA mats, 4 mixture solvents [hexafluoro-2-propanol, 2,2,2,-trifluoroethanol:dimethylformamide (9:1), 2,2,2,-trifluoroethanol:hexafluoro-2-propanol (9:1), chloroform] were used.

Nanofiber mats composed of a chitosan-poly(d,l-lactic-co-glycolic acid)-poly(ethylene oxide) blend as a postoperative anti-adhesion agent.

Postoperative tissue adhesion causes serious complications and suffering in 90% of patients after peritoneum surgery, while commercial anti-adhesion agents cannot completely prevent postoperative peritoneal adhesions. This study demonstrates electrospining of a blended solution of chitosan, poly(d,l-lactic-co-glycolic acid) (PLGA), and poly(ethylene oxide) (PEO) to fabricate a chitosan-based nanofibrous mat as a postoperative anti-adhesion agent. Rheological studies combined with scanning electron microscopy reveal that the spinnability of the chitosan-PLGA solution could be controlled by adjusting the blend ratio and concentration with average fiber diameter from 634 to 913 nm.

Antimicrobial Silver Chloride Nanoparticles Stabilized with Chitosan Oligomer for the Healing of Burns.

Recently, numerous compounds have been studied in order to develop antibacterial agents, which can prevent colonized wounds from infection, and assist the wound healing. For this purpose, novel silver chloride nanoparticles stabilized with chitosan oligomer (CHI-AgCl NPs) were synthesized to investigate the influence of antibacterial chitosan oligomer (CHI) exerted by the silver chloride nanoparticles (AgCl NPs) on burn wound healing in a rat model. The CHI-AgCl NPs had a spherical morphology with a mean diameter of 42 ± 15 nm.

Injectable pullulan hydrogel for the prevention of postoperative tissue adhesion.

Methods for reducing and preventing postoperative abdominal adhesions have been researched for decades; however, despite these efforts, the formation of postoperative peritoneal adhesions is continuously reported. Adhesions cause serious complications such as postoperative pain, intestinal obstruction, and infertility. Tissue adhesion barriers have been developed as films, membranes, knits, sprays, and hydrogels.

Fabrication and characterization of thermoresponsive polystyrene nanofibrous mats for cultured cell recovery.

Rapid cell growth and rapid recovery of intact cultured cells are an invaluable technique to maintain the biological functions and viability of cells. To achieve this goal, thermoresponsive polystyrene (PS) nanofibrous mat was fabricated by electrospinning of PS solution, followed by the graft polymerization of thermoresponsive poly(N-isopropylacrylamide)(PIPAAm) on PS nanofibrous mats. Image analysis of the PS nanofiber revealed a unimodal distribution pattern with 400 nm average fiber diameter.

Effect of methylcellulose on the formation and drug release behavior of silk fibroin hydrogel.

In this study, methylcellulose (MC) was used to control the gelation time of silk fibroin (SF) aqueous solution. The gelation time was measured using a Vibro Viscometer at 50 °C. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and a texture meter were used to investigate the effect of MC on the hydrogelation of SF solution.

Efficient formation of cell spheroids using polymer nanofibers.

Spheroid culture has been used for suspension cultures of anchorage-dependent cells. In this study, we developed a new method for the suspension cultures of anchorage-dependent animal cells using polymer nanofibers. Poly(lactic-co-glycolic acid) nanofibers (785 nm in average fiber-diameter, 88 μm in average fiber-length) fabricated by the electrospinning method were added to each suspension culture of human embryonic kidney 293 cells and human dermal fibroblasts.

Resorbable scaffolds from three different techniques: electrospun fabrics, salt-leaching porous films, and smooth flat surfaces.

Nanofibrous scaffolds of poly[(L-lactide)-co-(1,5-dioxepan-2-one)] generated by electrospinning have been compared with porous films obtained by solvent cast/salt leaching and homogeneous films. A comparison between the fibrous materials and the homogeneous solvent-cast films revealed that the surface of the nanofibers was more hydrophobic and that the nanofibers were degraded more rapidly in the presence of proteinase. It was obvious that the strain-to-break was reduced by the nanofiber formation, it decreased from 370% to 130% independent of fiber diameter.

Electrospinning of microbial polyester for cell culture.

Biodegradable and biocompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a copolymer of microbial polyester, was fabricated as a nanofibrous mat by electrospinning. The specific surface area and the porosity of electrospun PHBV nanofibrous mat were determined. When the mechanical properties of flat film and electrospun PHBV nanofibrous mats were investigated, both the tensile modulus and strength of electrospun PHBV were less than those of cast PHBV film.

Electrospun PHBV/collagen composite nanofibrous scaffolds for tissue engineering.

Electrospinning has recently emerged as a leading technique for the formation of nanofibrous structures made of synthetic and natural extracellular matrix components. In this study, nanofibrous scaffolds were obtained by electrospinning a combination of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and type-I collagen in 1,1,1,3,3,3-hexafluoro-2-isopropanol (HIFP). The resulting fibers ranged from 300 to 600 nm in diameter.

A composite of hydroxyapatite with electrospun biodegradable nanofibers as a tissue engineering material.

Biodegradable and biocompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a copolymer of microbial polyester, was fabricated as a nanofibrous film by electrospinning and composited with hydroxyapatite (HAp) by soaking in simulated body fluid. Compared with a PHBV cast (flat) film, the electrospun PHBV nanofibrous film was hydrophobic. However, after HAp deposition, both of the surfaces were extremely hydrophilic.