Characterization of the structural and molecular interactions of Ferulic acid ethyl ester with human serum albumin and Lysozyme through multi-methods.

Ferulic acid ethyl ester (FAEE) is an essential raw material for the formulation of drugs for cardiovascular and cerebrovascular diseases and leukopenia. It is also used as a fixed aroma agent for food production due to its high pharmacological activity. In this study, the interaction of FAEE with Human serum albumin (HSA) and Lysozyme (LZM) was characterized by multi-spectrum and molecular dynamics simulations at four different temperatures. Additionally, the quenching mechanism of FAEE-HSA and FAEE-LZM were explored. Meanwhile, the binding constants, binding sites, thermodynamic parameters, molecular dynamics, molecular docking binding energy, and the influence of metal ions in the system were evaluated. The results of Synchronous fluorescence spectroscopy, UV-vis spectroscopy, CD, three-dimensional fluorescence spectrum, and resonance light scattering showed that the microenvironment of HSA and LZM and the protein conformation changed in the presence of FAEE. Furthermore, the effects of some common metal ions on the binding constants of FAEE-HSA and FAEE-LZM were investigated. Overall, the experimental results provide a theoretical basis for promoting the application of FAEE in the cosmetics, food, and pharmaceutical industries and significant guidance for food safety, drug design, and development.

Fabrication of a modified bacterial cellulose with different alkyl chains and its prevention of abdominal adhesion.

Abdominal hernia mesh is a common product which is used for prevention of abdominal adhesion and repairing abdominal wall defect. Currently, designing and preparing a novel bio-mesh material with prevention of adhesion, promoting repair and good biocompatibility simultaneously remain a great bottleneck. In this study, a novel siloxane-modified bacterial cellulose (BC) was designed and fabricated by chemical vapor deposition silylation, then the effects of different alkyl chains length of siloxane on surface properties and cell behaviors were explored. The effect of preventing of abdominal adhesion and repairing abdominal wall defect in rats with the siloxane-modified BC was evaluated. As the grafted alkyl chains become longer, the surface of the siloxane-modified BC can be transformed from super hydrophilic to hydrophobic. In vivo results showed that BC-C16 had good long-term anti-adhesion effect, good tissue adaptability and histocompatibility, which is expected to be used as a new anti-adhesion hernia repair material in clinic.

Damage evolution law and failure mechanism of rock impacted by high-pressure water jet under in-situ stress condition.

To investigate the real physical mechanism of rock fragmentation subjected to water jet under in-situ stress condition, a numerical model based on the SPH algorithm was established using the rate-dependent constitutive model to simulate the rock-breaking process. First, the damage evolution law of rock impacted by high-pressure water jet under in-situ stress conditions was studied by analyzing the distribution characteristics of the damage field in the dynamic process of water jet impinging. The results showed that the damage field, widths of surface damage, maximum widths of damage and mean depths of damage of rock decreased with the increase of in-situ stress, indicating that the existence of initial in-situ stress had a strong inhibitory effect on rock fragmentation. The attenuation of the maximum widths of damage could be divided into two stages. The mean depths of damage of rock played a leading role in the number of damage elements. Furthermore, on this basis, the real physical mechanism of rock fragmentation subjected to water jet under in-situ stress condition was revealed by analyzing the stress states and damage history variables of the particles in the selected five typical regions. The study showed that the failure type of the upper rock elements in the crushing zone was brittle failure caused by a combination of compressive stress and shear stress with or without in-situ stress. However, the failure mechanisms of rock elements in crack zone were completely different with or without in-situ stress. In the absence of in-situ stress, the failure type of rock impacted by water jet was the coexistence of damage caused by compressive-shear stress and tensile stress, while in the presence of in-situ stress, the failure type of rock impacted by water jet was mainly the damage caused by compressive-shear stress.

Stability analysis of rock slope and calculation of rock lateral pressure in foundation pit with structural plane and cave development.

In this study, numerical simulations were carried out to analyze the influence of caves in different positions and shapes, in combination with structural planes, on the stability of the slope and the failure characteristics of a rock slope in a deep foundation pit with high inclination structural planes and cave development. The schemes for substituting a single karst cave for karst caves were constructed. Based on the penetration failure characteristics of karst caves between parallel structural planes, calculation methods for the safety factor of the rock foundation pits and the upper bound of the lateral pressure of supporting structures under the combined influence of the caves and structural planes have been developed, which can be used to assess the safety factor of a rock mass and to calculate the lateral pressure under complex geological conditions. The example of Xuzhou Metro Line 3 Sanhuan South Road Station is taken as an example to verify. The displacement calculation results show that the proposed rock and soil pressure calculation method is close to the actual measured value.

A novel bioactive polyurethane with controlled degradation and L-Arg release used as strong adhesive tissue patch for hemostasis and promoting wound healing.

Effective strategy of hemostasis and promoting angiogenesis are becoming increasingly urgent in modern medicine due to millions of deaths caused by tissue damage and inflammation. The tissue adhesive has been favored as an optimistic and efficient path to stop bleeding, while, current adhesive presents limitations on wound care or potential degradation safety in clinical practice. Therefore, it is of great clinical significance to construct multifunctional wound adhesive to address the issues. Based on pro-angiogenic property of l-Arginine (L-Arg), in this study, the novel tissue adhesive (G-DLPUs) constructed by L-Arg-based degradable polyurethane (DLPU) and GelMA were prepared for wound care. After systematic characterization, we found that the G-DLPUs were endowed with excellent capability in shape-adaptive adhesion. Moreover, the L-Arg released and the generation of NO during degradation were verified which would enhance wound healing. Following the in vivo biocompatibility was verified, the hemostatic effect of the damaged organ was tested using a rat liver hemorrhage model, from which reveals that the G-DLPUs can reduce liver bleeding by nearly 75% and no obvious inflammatory cells observed around the tissue. Moreover, the wound care effect was confirmed in a mouse full-thickness skin defect model, showing that the hydrogel adhesive significantly improves the thickness of newly formed dermis and enhance vascularization (CD31 staining). In summary, the G-DLPUs are promising candidate to act as multifunctional wound care adhesive for both damaged organ and trauma.

In-situ self-assembly of bacterial cellulose/poly(3,4-ethylenedioxythiophene)-sulfonated nanofibers for peripheral nerve repair.

Biocompatible and electroactive biomaterials have good potential on peripheral nerve repair. Bacterial cellulose (BC) shows excellent biocompatibility and is easy to modified, however it lacks electroactivity. In this study, biocompatible, conductive, and transparent bacterial cellulose/poly(3,4-ethylenedioxythiophene)-sulfonated nanofibers (BC/PEDOT-SNFs, BPS) composite membranes were prepared through the in-situ polymerization of PEDOT and the doping of SNFs. The polymerization of PEDOT endowed BC with conductivity, making the BPS membranes conducive to the adhesion and proliferation of adipose-derived stem cells (ADSCs). The conductivity of BPS was affected by the SNFs doped, and its value was up to 1.8 × 10-2 S/cm while the sulfonation degree of SNFs reached 93%. Furthermore, nerve conduits made of BPS were implanted in-vivo for 12 weeks, and it great improved the peripheral nerve repair effect. In summary, BPS membranes with excellent conductivity and multiple merits for cells loading, hold great application potential for peripheral nerve repair.

Polylysine-decorated macroporous microcarriers laden with adipose-derived stem cells promote nerve regeneration in vivo.

Cell transplantation is an effective strategy to improve the repair effect of nerve guide conduits (NGCs). However, problems such as low loading efficiency and cell anoikis undermine the outcomes. Microcarriers are efficient 3D cell culture scaffolds, which can also prevent cell anoikis by providing substrate for adhesion during transplantation. Here, we demonstrate for the first time microcarrier-based cell transplantation in peripheral nerve repair. We first prepared macroporous chitosan microcarriers (CSMCs) by the emulsion-phase separation method, and then decorated the CSMCs with polylysine (pl-CSMCs) to improve cell affinity. We then loaded the pl-CSMCs with adipose-derived stem cells (ADSCs) and injected them into electrospun polycaprolactone/chitosan NGCs to repair rat sciatic nerve defects. The ADSCs-laden pl-CSMCs effectively improved nerve regeneration as demonstrated by evaluation of histology, motor function recovery, electrophysiology, and gastrocnemius recovery. With efficient cell transplantation, convenient operation, and the multiple merits of ADSCs, the ADSCs-laden pl-CSMCs hold good potential in peripheral nerve repair.

Expressions of CD44, PCNA and MRP1 in lung cancer tissues and their effects on proliferation and invasion abilities of lung cancer cell line 95D.

PURPOSE: To investigate the expressions of CD44 non-small cell lung cancer cells, proliferating cell nuclear antigen (PCNA) and multidrug resistance-associated protein 1 (MRP1) in the lung cancer tissues and their effects on the proliferation and invasion abilities in vitro of lung cancer cell line 95D. METHODS: 138 lung cancer tissues and 127 adjacent normal tissues were collected from lung cancer patients after operation in Shandong Provincial Third Hospital from January 2015 to December 2017. CD44 siRNA (experimental CD44 group), PCNA siRNA (experimental PCNA group) and MRP1 siRNA (experimental MRP1 group) were transfected into human lung cancer 95D cells, and a negative control group (cells transfected with miR-Native Control) and a blank group (untransfected cells) were established. MTT assay was used for detecting the proliferation of cells, and Transwell chamber was used for detecting their invasion ability. RESULTS: The relative expressions of CD44, PCNA and MRP1 in the lung cancer tissues were higher than those in the adjacent tissues (p<0.050). At 24th h, the cell survival rate in the experimental MRP1 group was lower than that in the experimental PCNA group (p<0.050); At 48th the cell survival rate in the experimental MRP1 group was higher than that in the experimental CD44 group (p<0.050). At 72th h, the cell survival rate in the experimental PCNA group was significantly higher than that in the experimental CD44 group and the experimental MRP1 group (p<0.05). The cell invasion number in the experimental CD44 group, the experimental PCNA group and the experimental MRP1 group were significantly lower than cells in the negative control group and blank group (p<0.05). CONCLUSION: CD44, PCNA and MRP1, which may be involved in the regulation of the proliferation and invasion abilities of lung cancer cells, may serve as new molecular targeting markers for the diagnosis and treatment of lung cancer.

Cellulose fibers-reinforced self-expanding porous composite with multiple hemostatic efficacy and shape adaptability for uncontrollable massive hemorrhage treatment.

Uncontrollable hemorrhage leads to high mortality and thus effective bleeding control becomes increasingly important in the military field and civilian trauma arena. However, current hemostats not only present limitation when treating major bleeding, but also have various side effects. Here we report a self-expanding porous composites (CMCP) based on novel carboxymethyl cellulose (CMC) fibers and acetalized polyvinyl alcohol (PVA) for lethal hemorrhage control. The CMC fibers with uniform fibrous structure, high liquid absorption and procoagulant ability, are evenly interspersed inside the composite matrix. The obtained composites possess unique fiber-porous network, excellent absorption capacity, fast liquid-triggered self-expanding ability and robust fatigue resistance, and their physicochemical performance can be fine-tuned through varying the CMC content. In vitro tests show that the porous composite exhibits strong blood clotting ability, high adhesion to blood cells and protein, and the ability to activate platelet and the coagulation system. In vivo hemostatic evaluation further confirms that the CMCP presents high hemostatic efficacy and multiple hemostatic effects in swine femoral artery major hemorrhage model. Additionally, the CMCP will not fall off from the injury site, and is also easy to surgically remove from the wound cavity after the hemostasis. Importantly, results of CT tomography and 3D reconstruction indicate that CMCP can achieve shape adaptation to the surrounding tissues and the wound cavities with different depths and shapes, to accelerate hemostasis while protecting wound tissue and preventing infection.

Plant protein modified natural cellulose with multiple adsorption effects used for bilirubin removal.

In this study, bacterial cellulose (BC)/soy protein isolate (SPI) composite membranes were prepared by in situ cross-linked polymerization, and used as efficient blood compatible adsorbents to remove bilirubin. The obtained composite membranes were successively characterized by FTIR, SEM, AFM, contact angle test and hemolysis assay, which exhibited unique protein coated 3D fibrous network structures, hydrophobic surfaces and outstanding blood compatibility due to the incorporation of SPI. The BC/SPI membranes with high SPI content showed high adsorption efficiency, short adsorption equilibrium time (2 h) and multiple adsorption effects on bilirubin. The adsorption rate for free bilirubin of BC/SPI5 membrane could reach 78.8% when the bilirubin concentration was 100 mg L-1, while it increased to over 96.5% when the initial bilirubin concentration exceeded 400 mg L-1. More importantly, the BC/SPI5 membrane still exhibited high adsorption rate (over 70%) in presence of albumin. Furthermore, the composite membrane could also maintain high dynamic adsorption efficiency in self-made hemoperfusion devices. This novel naturally-derived membrane is an economical and efficient absorbent for the remove of bilirubin, and will provide new ideas for therapy of hemoperfusion without plasma separation process.

Design and characterization of plasticized bacterial cellulose/waterborne polyurethane composite with antibacterial function for nasal stenting.

A nasal stent capable of preventing adhesions and inflammation is of great value in treating nasal diseases. In order to solve the problems of tissue adhesion and inflammation response, we prepared plasticized bacterial cellulose (BCG) and waterborne polyurethane (WPU) composite with antibacterial function used as a novel nasal stent. The gelation behavior of BCG could contribute to protecting the paranasal sinus mucosa; meanwhile, the WPU with improved mechanical property was aimed at supporting the narrow nasal cavity. The thickness, size and the supporting force of the nasal stent could be adjusted according to the specific conditions of the nasal. Thermogravimetric analysis, contact angle and water absorption test were applied to investigate the thermal, hydrophilic and water absorption properties of the composite materials. The composite materials loaded with poly(hexamethylene biguanide) hydrochloride maintained well antibacterial activity over 12 days. Animal experiments further revealed that the mucosal epithelium mucosae damage of BCG-WPU composite was minor compared with that of WPU. This new type of drug-loaded nasal stent can effectively address the postoperative adhesions and infections while ensuring the health of nasal mucosal, and thus has an immense clinical application prospects in treating nasal diseases.

Comparison of the diagnostic value of CEA combined with OPN or DKK1 in non-small cell lung cancer.

Carcinoma embryonic antigen (CEA), osteopontin (OPN), and Dickkopf-1 (DKK1) expressed in serum are associated with hypoxia in tumor progression. However, the role of these proteins in the plasma of patients with non-small cell lung cancer (NSCLC) is poorly understood. The diagnostic values of CEA combined with OPN or DKK1 were compared in non-small cell lung cancer. This study investigated the diagnostic value of CEA combined with OPN and DKK1, respectively, in NSCLC. Eighty patients with NSCLC (NSCLC group) and 60 patients with benign lung diseases (benign lung disease group) admitted to Shandong Provincial Third Hospital from May 2014 to January 2015 were selected as the study subjects. In addition, 60 healthy subjects undergoing normal physical examination were selected as healthy control group. The OPN and DKK1 in serum of the two groups were detected by enzyme linked immunosorbent assay (ELISA), and the CEA expression was measured by Electrochemical Photometric method. The diagnostic value of CEA combined with OPN and DKK1, respectively, in NSCLC was analyzed. The expression of CEA, OPN, and DKK1 in serum of NSCLC group was significantly higher than that of healthy control group and benign lung disease group (P<0.05). The expression of CEA, OPN and DKK1 in serum of NSCLC patients was correlated with tumor diameter, lymph node metastasis, degree of pathological differentiation and clinical stage (P<0.05). ROC curve for diagnosis of NSCLC was drawn by further combination of serum CEA and OPN. The AUC of combined diagnosis of CEA and OPN for NSCLC was 0.920 (95% CI, 0.875-0.964), and the diagnostic sensitivity and specificity were 87.50 and 86.67%, respectively; the AUC of combined diagnosis of CEA and DKK1 for NSCLC was 0.912 (95% CI, 0.866-0.958), and the diagnostic sensitivity and specificity were 92.50 and 76.67%, respectively. CEA, OPN and DKK1 may be involved in the occurrence and progression of NSCLC and have good sensitivity and specificity in the diagnosis of NSCLC and may be new biomarkers for the diagnosis of NSCLC.

Silver nanoparticles stimulate osteogenesis of human mesenchymal stem cells through activation of autophagy.

Aim: Previously, different results have been achieved regarding effects of silver nanoparticles (Ag NPs) on osteogenesis of stem cells and the mechanisms have not been disclosed yet, which are quite important for potential application of Ag NPs in bone reconstruction. Materials & methods: Effects of Ag NPs on osteogenesis of human mesenchymal stem cells (hMSCs) with underlying mechanisms were investigated. Results: Ag NPs at 2.5 and 5 µg/ml increased osteogenic proteins expression and mineralization of hMSCs. Meanwhile, autophagy was activated by Ag NPs and it could be inhibited by 3-methyladenine. Furthermore, osteogenesis induced by Ag NPs could also be reversed by 3-methyladenine. Conclusion: These findings suggest that autophagy is involved in stimulating osteogenesis of hMSCs induced by Ag NPs.

An ultrasound-controllable release system based on waterborne polyurethane/chitosan membrane for implantable enhanced anticancer therapy.

Anti-relapse therapy after surgery plays a critical role in cancer therapy. New strategies maximizing the delivery of drugs to tumor cells while reducing toxic side effects on normal tissues and organs are still urgently required. In order to solve the problems of the poor delivery and inadequate distribution of cytotoxic chemotherapeutic drugs in the clinical application, an ultrasound-controllable and implantable release-system that utilized waterborne polyurethane (WPU) and chitosan (CS) composite membrane as drug carrier with wide flexible loading capacity for doxorubicin (DOX) was described in present work. Benefiting from the hydrophilic segment in WPU and bioactivity of amino groups on side chains of CS, the resulting composite films exhibited fine biodegradability, favorable cytocompatibility and excellent blood compatibility. The in vitro release studies illustrated that the drug-loading membranes displayed a well sustained release effect manifested in slow release, stability and no sudden release, and the DOX was able to release in an ultrasound-controlled manner. Cellular uptake assay and CCK 8 assay showed that the DOX can be released efficiently from the drug-loading matrix and taken up by tumor cells. As a means of adjuvant local treatment, this work provided a facile approach to the design of ultrasound-regulated membrane matrix that is highly beneficial not only due to the higher and long-term therapeutic efficiency, and improvement of utilization efficiency of chemotherapeutic drugs but also the low toxicity to normal cells.

Highly transparent, highly flexible composite membrane with multiple antimicrobial effects used for promoting wound healing.

In recent years, bacterial cellulose (BC)-based dressings or patches for skin or soft tissue repair have become investigative emphasis. However, most of the BC-based products used for biomedical applications present limitations due to their low flexibility, poor gas permeability and no inherent antibacterial activity. Herein, we proposed and designed a novel composite composed of natural bacterial cellulose (BC), polyethylene glycol (PEG) and polyhexamethylene biguanidine (PHMB) through new synthetic approaches. The composite membrane exhibited favorable physicochemical performance, especially transparency, water retention ability, flexibility as well as the characteristic of anti-adhesion. In vitro biochemical experiment results indicated that the composite had excellent biocompatibility and exhibited strong and sustained antibacterial effect. In vivo test further demonstrated that the composite could efficiently promote skin wound healing and regeneration in a rat model. This composite membrane possesses multiple mechanisms of promoting cutaneous wound healing and will provide new ideas for future development of wound dressings.

MiR-216b suppresses cell proliferation, migration, invasion, and epithelial-mesenchymal transition by regulating FOXM1 expression in human non-small cell lung cancer.

Background/aims: MiR-216b and forkhead box M1 (FOXM1) were demonstrated to exert their biological effects on the development and progression of tumors. This study aimed to investigate the expression and role of miR-216b and FOXM1 in tissues and cell lines of non-small cell lung cancer (NSCLC). Methods: The expressions of miR-216b and FOXM1 in NSCLC tissues and cells were detected by qRT-PCR and Western blot analysis. Cell proliferation was measured by CCK-8 assay. Cell migration and invasion were confirmed by Transwell assay. Finally, the bioinformatics and dual-luciferase reporter assay were conducted to validate the relationship of miR-216b and FOXM1. Results: Compared with normal tissues and cells, the expression of miR-216b was obviously decreased in NSCLC tissues and cells. However, the expressions of FOXM1 mRNA and protein were significantly increased, and negatively correlated with the expression of miR-216b. Multivariate Cox's regression analysis suggested that miR-216b or FOXM1 expression was an independent prognostic factor for patients with NSCLC. MiR-216b overexpression remarkably repressed cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of NSCLC cells. The bioinformatics and dual-luciferase reporter assay validated that the 3'-untranslated region (3'-UTR) of FOXM1 mRNA was indeed a direct target of FOXM1. In vitro, overexpression of FOXM1 partially eliminated inhibitory effects of miR-216b on cell proliferation, migration, and invasion, whereas inhibition of FOXM1 contributed to inhibitory effects mediated by miR-216b. Conclusion: MiR-216b inhibits cell proliferation, migration, invasion, and EMT by targeting the expression of FOXM1 in human NSCLC. These findings suggested a potential therapeutic role of miR-216b in patients of NSCLC.

Esculetin enhances the inhibitory effect of 5-Fluorouracil on the proliferation, migration and epithelial-mesenchymal transition of colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is the most common malignant disease worldwide and thus new therapeutic approaches are needed. 5-Fluorouracil (5-FU) remains the most widely used agent to treat colorectal cancer (CRC). However, its clinical efficacy is currently limited by the development of drug resistance. Esculetin (EST), a coumarin, was found to have anti-proliferative and anti-migration activity in cancer. OBJECTIVE: This research aims to evaluated the influence and possible mechanism of EST on the proliferation, migration and epithelial-mesenchymal transition of CRC cell lines. MATERIALS AND METHODS: Human CRC cell lines HT-29, SW480, HCT-116, and Caco-2 were treated with various concentrations of EST (0.2, 2, 20, 200, 2000 µg/ml) or 5-FU (0.1, 1, 10, 100, 1000 µg/ml) for 48 h, and cell viability was determined by the MTT and CCK-8 assay. The motility of HCT-116 cells was detected by scratch assay. Western blot was applied to detect the protein expression. Besides, levels of Wnt3a and VEGF in HCT-116 cell culture medium supernatant were analyzed by ELISA. The anti-tumor effect was detected with HCT-116 subcutaneous tumor bearing tumor model by monitoring the tumor vomume in vivo. Finally, the tumoral expression of VEGF was measured by immunohistochemistry, and the expression of Ki67, PCNA, ß-catenin, c-Myc, Cyclin D1, MMP2 and MMP7 was measured by Western blot analysis. RESULTS: EST inhibited HCT-116 cell proliferation in a dose-dependent manner. Western blot analysis revealed that EST decreased the expression of Ki67, PCNA, N-cadherin, E-cadherin, vimentin, fibronectin, ß-catenin, c-Myc, Cyclin D1, MMP2 and MMP7. Furthermore, EST reduced the release of Wnt3a and VEGF into HCT-116 cells culture medium. After EST treatment, the tumor volume was significant smaller than that of the control group, and the tumoral levels of VEGF were decreased. Moreover, western blot analysis indicated that the expression of Ki67, PCNA, ß-catenin, c-Myc, Cyclin D1, MMP2 and MMP7 were also significantly decreased after treated with EST. In addition, in vitro and in vivo anti-tumor results demonstrated that EST combined with 5-FU could increase the inhibitory effect of 5-FU on HCT-116 cells proliferation, migration and epithelial-mesenchymal transition. CONCLUSIONS: EST enhances the inhibitory effect of 5-FU on the proliferation, migration and epithelial-mesenchymal transition of CRC.

Words Can Shift: Dynamically Adjusting Word Representations Using Nonverbal Behaviors.

Humans convey their intentions through the usage of both verbal and nonverbal behaviors during face-to-face communication. Speaker intentions often vary dynamically depending on different nonverbal contexts, such as vocal patterns and facial expressions. As a result, when modeling human language, it is essential to not only consider the literal meaning of the words but also the nonverbal contexts in which these words appear. To better model human language, we first model expressive nonverbal representations by analyzing the fine-grained visual and acoustic patterns that occur during word segments. In addition, we seek to capture the dynamic nature of nonverbal intents by shifting word representations based on the accompanying nonverbal behaviors. To this end, we propose the Recurrent Attended Variation Embedding Network (RAVEN) that models the fine-grained structure of nonverbal subword sequences and dynamically shifts word representations based on nonverbal cues. Our proposed model achieves competitive performance on two publicly available datasets for multimodal sentiment analysis and emotion recognition. We also visualize the shifted word representations in different nonverbal contexts and summarize common patterns regarding multimodal variations of word representations.

In situ synthesis of bacterial cellulose/copper nanoparticles composite membranes with long-term antibacterial property.

Bacterial cellulose (BC), with unique structure and properties, has attracted much attention in the biomedical field, especially in using as wound dressing. However, pure BC lacks the antimicrobial activity, which limits its application in wound healing. To solve this problem, copper nanoparticles (Cu NPs) loaded BC membranes were fabricated by using in situ chemical reduction method. The morphology and chemical composition of the composite membranes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA). The results showed that Cu NPs evenly distributed and anchored in the three-dimensional (3-D) nanofiber network of BC through physical bonding. Traces of Cu2O were observed on the membranes probably because the Cu2+ was incompletely reduced. The Cu NPs loaded BC membranes showed efficient long-term antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) even after immersion in deionized water for up to 90 days. The composite membranes kept sustained release of copper ion, which may contribute to the long-term antibacterial activity. Furthermore, with controlled Cu concentration, BC/Cu membranes did not show obvious cytotoxicity to normal human dermal fibroblasts (NHDF). In all, the present results reveal that BC/Cu membranes with efficient antibacterial activity are promising to be used as wound dressings.