Chitosan-based hydrogel dressings for diabetic wound healing via promoting M2 macrophage-polarization.

A long-term inflammatory phase of diabetic wounds is the primary cause to prevent their effective healing. Bacterial infection, excess reactive oxygen species (ROS), especially failure of M2-phenotype macrophage polarization can hinder the transition of diabetic wounds from an inflammation phase to a proliferation one. Herein, a chitosan-based hydrogel dressing with the ability of regulating M2 macrophage polarization was reported. The PAAc/CFCS-Vanillin hydrogel dressing was synthesized by one step thermal polymerization of catechol-functionalized chitosan (CFCS), acrylic acid, catechol functional methacryloyl chitosan­silver nanoparticles (CFMC-Ag NPs) and bioactive vanillin. The PAAc/CFCS-Vanillin hydrogel possessed sufficient mechanical strength and excellent adhesion properties, which helped rapidly block bleeding of wounds. Thanks to CFCS, CFMC-Ag NPs and vanillin in the hydrogel, it displayed excellent antibacterial infection in the wounds. Vanillin helped scavenge excess ROS and regulate the levels of inflammatory factors to facilitate the polarization of macrophages into the M2 phenotype. A full-thickness skin defect diabetic wound model showed that the wounds treated by the PAAc/CFCS-Vanillin hydrogel exhibited the smallest wound area, and superior granulation tissue regeneration, remarkable collagen deposition, and angiogenesis were observed in the wound tissue. Therefore, the PAAc/CFCS-Vanillin hydrogel could hold promising potential as a dressing for the treatment of diabetic chronic wounds.

Unraveling Ros Conversion Through Enhanced Enzyme-Like Activity with Copper-Doped Cerium Oxide for Tumor Nanocatalytic Therapy.

Nanozyme catalytic therapy for cancer treatments has become one of the heated topics, and the therapeutic efficacy is highly correlated with their catalytic efficiency. In this work, three copper-doped CeO2 supports with various structures as well as crystal facets are developed to realize dual enzyme-mimic catalytic activities, that is superoxide dismutase (SOD) to reduce superoxide radicals to H2 O2 and peroxidase (POD) to transform H2 O2 to ∙OH. The wire-shaped CeO2 /Cu-W has the richest surface oxygen vacancies, and a low level of oxygen vacancy (Vo) formation energy, which allows for the elimination of intracellular reactive oxygen spieces (ROS) and continuous transformation to ∙OH with cascade reaction. Moreover, the wire-shaped CeO2 /Cu-W displays the highest toxic ∙OH production capacity in an acidic intracellular environment, inducing breast cancer cell death and pro-apoptotic autophagy. Therefore, wire-shaped CeO2 /Cu nanoparticles as an artificial enzyme system can have great potential in the intervention of intracellular ROS in cancer cells, achieving efficacious nanocatalytic therapy.

In Situ Implantation of Chitosan Oligosaccharide-Doped Lipoic Acid Hydrogel Breaks the "Vicious Cycle" of Inflammation and Residual Tumor Cell for Postoperative Skin Cancer Therapy.

Surgical excision is the main treatment for skin cancer, but the tumor recurrence caused by the "vicious cycle" between residual tumor cells and postoperative inflammation remains a challenge. Herein, a new material, which can break the "vicious cycle", was developed by incorporating chitosan oligosaccharides into lipoic acid hydrogel (COS@LA-hydrogel). When implanted at the resection site, the COS@LA-hydrogel would have a sustained release of LA and COS, which could not only kill residual tumor cells by synergistically reducing AKT phosphorylation but also decrease inflammation by inhibiting the expression of tumor necrosis factor-α (TNF-α) and inhibiting bacterial infection, respectively. As a proof of concept, in the postoperative melanoma resection model, the COS@LA-hydrogel reduced the expression of pro-inflammatory factors TNF-α and interleukin-6 (IL-6) by up to 78 and 80%, respectively, and they showed almost no tumors and the median survival of the mice was 2.5 times longer than that of the control group. The hydrogel with the function of "vicious cycle" breaking holds clinical potential.

Scavenging ROS and inflammation produced during treatment to enhance the wound repair efficacy of photothermal injectable hydrogel.

Injectable hydrogels with near infrared (NIR) photothermal ability show attractive application prospects in the treatment of wound infection and promoting skin defect repair. Nevertheless, excess reactive oxygen species (ROS) and inflammatory responses caused by bacterial infection and photothermal therapy (PTT) would delay tissue regeneration and wound healing. In this study, a novel NIR photothermal injectable hydrogel with anti-oxidation and anti-inflammation by incorporating α-lipoic acid modified palladium nanoparticles into calcium ions crosslinked sodium alginate hydrogel was developed. The resulting hydrogel facilitated to fill perfectly various irregular wounds, and could convert NIR light into local high-heat to kill >80 % of Escherichia coli and Staphylococcus aureus. Remarkably, the hydrogel exhibited excellent anti-oxidant and anti-inflammatory activity, which could scavenge >60 % of ROS in cells and decrease the relative expression level of tumor necrosis factor-alpha and interleukin-1ß genes by 52.9 % and 53.3 % respectively. It was found that the NIR photothermal injectable hydrogel with anti-oxidation and anti-inflammation could effectively reduce ROS and inflammation caused by bacterial infection and PPT. Additionally, it could also enhance wound repair efficiency. The hydrogel is expected to be a potential wound dressing for the treatment of clinical skin defects.

Polypseudorotaxane functionalized magnetic nanoparticles as a dual responsive carrier for roxithromycin delivery.

A magnetic-pH dual responsive drug delivery system was prepared for antibacterial therapy to reduce the side effects on nonpathological cells or tissues. Iron oxide (Fe3O4) core was surface-functionalized with silane coupling agents to link ß­cyclodextrin (ß-CD) (CDMNP), and a polypseudorotaxanes shell where polyethyleneglycol chains threaded much CD molecules was further prepared on the magnetic Fe3O4 core (CDMNP-PEG-CD) to enhance loading capacity of roxithromycin (ROX). CDMNP-PEG-CD with a hydrodynamic diameter of ~168 nm was cytocompatible, superparamagnetic, magnetic-responsive and stable for 180 min of storage. No significant interaction with serum albumin was shown for the nanocomposites. The in vitro release from ROX-loaded CDMNP-PEG-CD nanocomposites was about 76% of total drug within 30 min at pH 1.0, 1.6-fold of that at pH 7.4 and 2-fold of that at pH 8.0, presenting pH-responsive drug release behaviors. The nanocomposites showed positive antibacterial activity against both E. coli and S. aureus based on an agar diffusion method. The antibacterial activity of the nanocomposites was more sensitive against E. coli than S. aureus, and the inhibition halo against E. coli was 85% more than that of Fe3O4. CDMNP-PEG-CD nanocomposites allowed for the localization and fast concentration of hydrophobic drugs, providing a broad potential range of therapeutic applications.

Cell-loaded carboxymethylcellulose microspheres sustain viability and proliferation of ATDC5 cells.

Cell-loaded carboxymethylcellulose (CMC) microspheres were generated via a flow focusing microfluidic device, with a final aim to obtain viable ATDC5 aggregates with sustained proliferation capacity. We synthesized various CMC with phenolic groups (CMC-Ph) and demonstrated that high CMC-Ph molecular weight, high CMC-Ph concentration (>0.8 g/ml) or long culturing period had obvious inhibition effect on ATDC5 proliferation, but low horseradish peroxidase concentration (HRP, <0.4 mg/ml) did not. CMC-Ph gels being obtained through HRP/H2O2 reaction showed an enhancing strength and decreasing break stain as the molecular weight of CMC-Ph increased, along with a decreasing gelation time. The microfluidics-based synthesis of cell-loaded microspheres with great design flexibilities was achieved using CMC-Ph with weight-average molecular weight of 1.0 × 105. ATDC5 cells were viable up to 41 days of culture and proliferated gradually with increasing culture time. High cell density in CMC-Ph solution and high fetal bovine serum concentration in culture medium were prone to forming cell aggregates. Isolated cells from the microspheres showed the typical spherical morphology of undifferentiated ATDC5. Therefore, CMC-Ph microspheres might be used as cell aggregates depots to study cell-cell or cell-biomaterials functions for tissue engineering applications.