Degradation of polyethylene by Klebsiella pneumoniae Mk-1 isolated from soil.

The massive accumulation of polyethylene (PE) in the natural environment has caused persecution to the ecological environment. At present, the mechanism of microbial degradation of PE remains unclear, and the related enzymes for degrading PE need to be further explored. In this study, a strain of Klebsiella pneumoniae Mk-1 which can effectively degrade PE was obtained from the soil. The degradation performance of the strains was evaluated by weight loss rate, SEM, ATR/FTIR, WCA, and GPC. The key gene of PE degradation in the strain was further searched, which may be the laccase-like multi-copper oxidase gene. Then, the laccase-like multi-copper oxidase gene (KpMco) was successfully expressed in E.coli and its laccase activity was verified, which reached 85.19 U/L. The optimum temperature and pH of the enzyme are 45 °C and 4.0, respectively; it shows good stability at 30-40 °C and pH 4.5-5.5; Mn2+ and Cu2+ can activate the enzyme effect. After the enzyme was applied to the degradation of PE film, it was found that the laccase-like multi-copper oxidase did have a certain degradation effect on PE film. This study provides new strain and enzyme gene resources for the biodegradation of PE, thereby promoting the process of PE biodegradation.

Bacterial Cellulose-Based Bandages with Integrated Antibacteria and Electrical Stimulation for Advanced Wound Management.

Bandages for daily wounds are the most common medical supplies, but there are still ingrained defects in their appearance, comfort, functions, as well as environmental pollution. Here, novel bandages based on bacterial cellulose (BC) membrane for wound monitoring and advanced wound management are developed. The BC membrane is combined with silver nanowires (AgNWs) by using vacuum filtration method to achieve transparent, ultrathin (≈7 µm), breathable (389.98-547.79 g m-2  d-1 ), and sandwich-structured BC/AgNWs bandages with superior mechanical properties (108.45-202.35 MPa), antibacterial activities against Escherichia coli and Staphylococcus aureus, biocompatibility, and conductivity (9.8 × 103 -2.0 × 105  S m-1 ). Significantly, the BC/AgNWs bandage is used in the electrical stimulation (direct current, 600  microamperes for 1 h every other day) treatment of full-thickness skin defect in rats, which obviously promotes wound healing by increasing the secretion of vascular endothelial growth factor (VEGF). The BC bandage is used for monitoring wounds and achieve a high accuracy of 94.7% in classifying wound healing stages of hemostasis, inflammation, proliferation, and remodeling, by using a convolutional neural network. The outcomes of this study not only provide two BC-based bandages as multifunctional wound management, but also demonstrate a new strategy for the development of the next generation of smart bandage.

Holey Ti3C2 nanosheets based membranes for efficient separation and removal of microplastics from water.

The accumulation of non-degradable microplastics (MPs) originated from the mass production and huge consumption of plastics of modern industry in the water environment has resulted in severe pollution problems globally. Herein, we report for the first time the preparation of holey Ti3C2Tx (h-Ti3C2Tx) membranes obtained by etching Co3O4 nanoparticles embedded on Ti3C2Tx nanosheets followed by simple vacuum filtration using polymeric membranes as supporting matrix for efficient removal of MPs from wastewater. The h-Ti3C2Tx nanosheets exhibit a planar porous structure which present nano-holes with an average hole-size of 25 nm in diameter, which facilitated the construction of membranes with better water flux for the separation of MPs. Using fluorescent PS (FP) microspheres of different diameters as microplastic models, the obtained h-Ti3C2Tx membranes exhibited extremely high MPs removal performance (up to 99.3% under our conditions). Moreover, a large water flux of 196.7 L h-1 m-2 k Pa-1 can be obtained, which can compete or be larger than that of most of the membranes composed of untreated two-dimension nanomaterials. Due to the physicochemical stability, tremendous large water reflux, and the high MPs removal efficiency of h-Ti3C2Tx membranes, there may be a great potential for practical applications in the separation and removal of various contaminants such as MPs or suspended solids from water.

Synergic cloud-point extraction using [C4mim][PF6] and Triton X-114 as extractant combined with HPLC for the determination of rutin and narcissoside in Anoectochilus roxburghii (Wall.) Lindl. and its compound oral liquid.

A green, novel and efficacious method for the simultaneous extraction and enrichment of rutin and narcissoside from the compound Anoectochilus roxburghii (Wall.) Lindl. oral liquid (CAROL) and Anoectochilus roxburghii (Wall.) Lindl. was developed. Ionic liquid-surfactant synergic cloud-point extraction (IL-CPE) was used to enrich two analytes, which were determined by high-performance liquid chromatography (HPLC). Some parameters affecting IL-CPE were optimized, such as ratio and volume of 1-butyl-3-methyl-imidazolium hexafluorophosphate and Triton X-114, pH of the sample, NaCl concentration, total extraction volume, incubation temperature and time, centrifuge rate and time. The corresponding linearity range for two analytes exhibited good linearity (r2＞0.9997), with the average added recoveries ranging from 92.1% to 98.9%. The limits of detection of rutin and narcissoside were 0.26 and 0.30 ng/mL, respectively. The method was successfully applied for the determination of two flavonoids in the complex-matrix sample, i.e. CAROL and the water extract of A. roxburghii. The mass spectrum data showed that the sample contained rutin and narcissoside. Compared with conventional extraction methods, IL-CPE exhibited higher extraction efficiency and better extraction selectivity. This method may provide a novel platform for the determination of active ingredients in compound Chinese medicine oral liquid and herb.

A pH-Triggered, Self-Assembled, and Bioprintable Hybrid Hydrogel Scaffold for Mesenchymal Stem Cell Based Bone Tissue Engineering.

Effective bone tissue engineering can restore bone and skeletal functions that are impaired by traumas and/or certain medical conditions. Bone is a complex tissue and functions through orchestrated interactions between cells, biomechanical forces, and biofactors. To identify ideal scaffold materials for effective mesenchymal stem cell (MSC)-based bone tissue regeneration, here we develop and characterize a composite nanoparticle hydrogel by combining carboxymethyl chitosan (CMCh) and amorphous calcium phosphate (ACP) (designated as CMCh-ACP hydrogel). We demonstrate that the CMCh-ACP hydrogel is readily prepared by incorporating glucono δ-lactone (GDL) into an aqueous dispersion or rehydrating the acidic freeze-dried nanoparticles in a pH-triggered controlled-assembly fashion. The CMCh-ACP hydrogel exhibits excellent biocompatibility and effectively supports MSC proliferation and cell adhesion. Moreover, while augmenting BMP9-induced osteogenic differentiation, the CMCh-ACP hydrogel itself is osteoinductive and induces the expression of osteoblastic regulators and bone markers in MSCs in vitro. The CMCh-ACP scaffold markedly enhances the efficiency and maturity of BMP9-induced bone formation in vivo, while suppressing bone resorption occurred in long-term ectopic osteogenesis. Thus, these results suggest that the pH-responsive self-assembled CMCh-ACP injectable and bioprintable hydrogel may be further exploited as a novel scaffold for osteoprogenitor-cell-based bone tissue regeneration.

Preparation of pH-responsive polymer core-shell nanospheres for delivery of hydrophobic antineoplastic drug ellipticine.

Antineoplastic drug ellipticine and its derivatives are used in human cancer therapy. However, their clinical applications have been limited by its great hydrophobicity and severe side effects. An efficient delivery system is therefore very desirable. In this research, an ellipticine-loaded core-shell structured nanosphere namely poly(DEAEMA)-poly(PEGMA) is designed as a drug carrier and prepared via a two-step semibatch emulsion polymerization method where DEAEMA and PEGMA represent 2-(diethylamino)ethyl methacrylate and poly(ethylene glycol) methacrylate, respectively. The in-vitro release profiles of ellipticine towards the different pH liposome vesicles are recorded as a function of time at 37 °C. It is found that release of ellipticine from the core-shell polymer matrix is a pH-responsive and controlled release process. The three pH's of 3, 4, and 5 trigger a significant ellipticine release of 88% after 98 h, 83% after 98 h, and 79% after 122 h, respectively. The release mechanism of ellipticine from the core-shell polymer matrix under acidic conditions is explored. The synthesis and encapsulation process developed herein provides a new perspective for the development of appropriate delivery systems to deliver the ellipticine and its analogues, as well as other types of hydrophobic drugs to a given target cell or tumor tissue.

[Sequential reduction and fixation for zygomatic complex fractures].

OBJECTIVE: To explore the procedure and effectiveness of sequential reduction and fixation for zygomatic complex fractures. METHODS: Between March 2004 and February 2012, 32 patients with zygomatic complex fractures were treated. There were 28 males and 4 females with a median age of 29 years (range, 17-55 years). Fractures were caused by traffic accident in 29 cases and by tumble in 3 cases. The time between injury and admission was 1-12 days (mean, 3 days) in 28 fresh fractures and 22-60 days (mean, 40 days) in 4 old fractures. All patients were diagnosed by clinical symptom and CT scan. Coronal scalp incision, lower eyelid aesthetic incision, and intraoral incision were used to expose the zygomatic bone segments. The sequence of fractures reduction and fixation was horizontal first, and then longitudinal. In horizontal orientation, reduction and simultaneous fixation started from the root of the zygoma, to zygomatic arch, body of the zygoma, and inferior orbital rim in turn. Longitudinally, fracture reduction of zygomatico-frontal suture and orbital posterolateral walls was done first, followed by fracture reduction of zygomaticomaxillary buttress. RESULTS: Primary healing of incision was obtained in all 32 cases, without complications of maxillary sinus fistula and infection. Eighteen patients were followed up 6 months to 6 years with a median time of 32 months. All the patients gained satisfactory results with normal zygomatic contour and symmetric midface. All patients restored normal mouth opening. No eye and vision damage occurred. Frontal disappearance and brow ptosis were observed in 2 cases. Hair loss (2-3 mm) was seen at the site of coronal scalp incision, without scar hyperplasia; there was no obvious scar at lower eyelid. CT and X-ray films showed bony healing at 6 months after operation. CONCLUSION: Sequential reduction and fixation is accord with the mechanical characters of complicated zygomatic fractures. It is very easy to achieve anatomic reduction of the bone segments and facial symmetry.

Sequential treatment of drug-resistant tumors with RGD-modified liposomes containing siRNA or doxorubicin.

Tumor targeting drug delivery systems are being the ideal carriers of systemic administration for tumor therapy. We have reported previously that RGD peptide (arginine-glycine-aspartic acid)-modified liposomes containing drugs could increase targeting to tumor by binding with the integrin receptors overexpressed on tumor cells. RNA interference plays an important role on down-regulation of P-glycoprotein (P-gp), which is a drug efflux transporter overexpressed on multi-drug-resistant (MDR) tumor cells. To improve MDR tumor therapy, sequential treatment strategy with RGD-modified liposomes containing P-gp targeted small interference (siRNA) or doxorubicin (DOX) was reported in this study. When targeted via RGD to tumor-cell-surface and tumor neovasculature endothelial cell receptors, cationic liposomes could specifically deliver siRNAs to tumor cells and thus reverse drug resistance by down-regulation of P-gp, following administration of targeted liposomes containing DOX that inhibit formerly drug-resistant tumors. From the current results, the combination use of DOX and P-gp targeted siRNA showed significantly higher in vitro cytotoxicity in tumor cells than liposomal DOX alone. In vivo studies in a mouse model of drug-resistant MCF7/A tumor demonstrated significantly greater inhibition of tumor growth followed by the sequential treatment of RGD-modified liposomes containing siRNA or DOX when compared to liposomal DOX alone. Also, ex vivo tissue imaging studies have shown the accumulation of siRNA and DOX in tumors at same site-specific manner. These results suggested that the sequential treatment of P-gp gene silencing and cytotoxic drug with RGD-modified liposome drug delivery system could be a promising clinical treatment for drug-resistant tumors.

Efficient intracellular delivery of oligonucleotides formulated in folate receptor-targeted lipid vesicles.

In this study, a novel lipid vector has been developed for targeted delivery of oligodeoxynucleotides (ODN) to tumors that overexpress folate receptor. This is based on a method developed by Semple et al. (1), which utilizes an ionizable aminolipid (1,2-dioleoyl-3-(dimethylammonio)propane, DODAP) and an ethanol-containing buffer system for encapsulating large quantities of polyanionic ODN in lipid vesicles. Folate is incorporated into the lipid vesicles via a distearoylphosphatidylethanolamine-poly(ethylene glycol) (DSPE-PEG) spacer. These vesicles are around 100-200 nm in diameter with an ODN entrapment efficiency of 60-80%. Folate mediated efficient delivery of ODN to KB cells that overexpress folate receptor. Uptake of folate-targeted lipidic ODN by KB cells is about 8-10-fold more efficient than that of lipidic ODN without a ligand or free ODN. This formulation is resistant to serum. Thus, targeted delivery of ODN via this novel lipid vector may have potential in treating tumors that overexpress folate receptors.