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An edible and structured emulsion gel was successfully prepared from thermo-gelable polysaccharide curdlan and regenerated cellulose (RC), which was characterized by a set of methods, such as, fluorescence microscopy, rheology analysis, etc. The preparation procedures included formulating an oil-in-water emulsion stabilized by RC and curdlan, followed by heat treatment leading to a structured solid system. The stable O/W type emulsion gel was acquired at the RC concentration above 0.5 wt % and curdlan above 1 wt %. The fluorescence microscopy proved the adsorption of RC on the oil droplets surface. Besides, the effect of temperature and RC/curdlan concentrations on the rheological behavior of emulsion gel was evaluated. G′, G″ and viscosity of the emulsion started to increase at around 50 °C and thermal irreversible gel formed at temperature 80 °C. Due to the reinforcement of entanglements and interactions, increasing RC/curdlan concentration contributed to an improvement of storage (G’) and loss (G”) moduli in emulsion gel, while reduced their creep compliance under microstress according to the creep measurements.

Cured isotropic conductive adhesive (ICA) with different conductive fillers (micro silver flakes) contents were prepared. Based on the loading mode of “rapid loading-holding-rapid unloading” and semi-empirical method from the generalized Kelvin model, micro-indentation tests were carried out to investigate the effect of hygrothermal aging on the mechanical properties of cured ICA. On the whole, the elastic modulus and hardness of cured ICA with high silver content are relatively larger. As the hygrothermal aging time increases, both elastic modulus and hardness decrease at first and then stabilize, and the creep deformation is more evident. Indentation creep displacement–time curves for cured ICA were characterized by the generalized Kelvin model. During the holding stage, creep compliance increases slowly at first and then increases quickly with modulus loss. With the aggravated aging creep compliance increases, and creep compliance of cured ICA with high silver content increases faster at the later stage of hygrothermal aging. The widened retardation peaks with increasing retardation time reflect the different retardation processes during the holding stage. With increasing aging time, the creep rate sensitivity exponent increases and creep resistance reduces accordingly.

Curdlan has wide potential application in the food and biomedical fields due to its unique thermal gel and biological activity. This study investigated the effect of six sugars including glucose, fructose, lactose, maltose, sucrose and xylose as carbon sources on production and properties of curdlan using Agrobacterium sp. DH-2. The maximum production (38.1 g/L and 37.4 g/L, respectively) and yield (0.58 g curdlan/g sucrose and 0.53 g curdlan/g maltose, respectively) of curdlan were achieved by sucrose and maltose, followed by glucose, fructose, lactose and xylose. Scanning electron micrographs showed that the surface of cells was smooth in strain growth phase, while cells were covered by curdlan matrix acted as a net in the curdlan synthesis phase. The highest glucosyltransferase activity (19.9 U/g biomass) corresponded to the maximum curdlan production using the sucrose medium. The molecular weight and gel strength of curdlan were influenced by the carbon sources. The curdlan from xylose medium resulted in a maximum molecular weight of 1.59 × 106 Da and the highest gel strength of 989.2 g/cm2, while the curdlan from sucrose medium resulted in a lowest molecular weight of 1.10 × 106 Da and gel strength of 672.8 g/cm2. The high molecular weight of curdlan had high gel strength.

Curdlan is a bacterial, water-insoluble, linear homopolysaccharide that has been widely used in the food industry. In this study, genome information of strain CGMCC 11546, a UV-induced high-yield mutant of the model curdlan-producing strain Agrobacterium sp. ATCC 31749, was used to investigate the molecular mechanism of curdlan biosynthesis. The maximum curdlan yield of 47.97 ± 0.57 g/L was obtained from strain CGMCC 11546 by using optimal media containing 60 g/L sucrose, 6 g/L yeast, 2 g/L KH2PO4, 0.4 g/L MgSO4·7H2O, 2 g/L CaCO3, 0.1 g/L FeSO4·7H2O, 0.04 g/L MnSO4, and 0.02 g/L ZnCl2 at 30 °C and 280 rpm after 96 h of fermentation. The gel strength of curdlan was improved by 41 % by knocking out the β-1,3-glucanase genes exoK and exsH of strain CGMCC 11546. Furthermore, the application of curdlan from the ΔexoK-exsH strain in noodles significantly improved the eating quality of both raw and cooked noodles.

In this work, different concentrations of Se-incorporated mesoporous silica nanospheres (MSNs) (5Se/MSNs and 10Se/MSNs) were successfully synthesized via an in-situ one-pot method. Their physicochemical properties were characterized by X-ray diffraction (XRD), transmission electron microscopy, and X-ray photoelectron spectroscopy (XPS). The release behaviors of Se and Si were investigated in a phosphate-buffered saline (pH = 5.5, 7.4) solution (PBS). In vitro antibacterial properties of the prepared samples were evaluated with Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The cytocompatibilities of the samples were then assessed using L929 cells. Se nanoparticles were successfully loaded onto the outer and inner surfaces of hierarchical mesoporous silica. The sizes of the Se/MSNs nanoparticles were approximately 120 nm for 5Se/MSNs and 210 nm for 10Se/MSNs. The XRD and XPS results showed that Se mainly existed in the form of Se0 in the samples. The Se/MSNs exhibited stable and sustained release of both Si and Se in PBS solution. In vitro antibactericidal tests indicated that the Se/MSNs could exhibit better antibacterial activity against S. aureus than pure Se nanoparticles after 6 and 24 h of culturing. The minimal inhibitory concentration (MIC) of 10Se/MSN was 100 μg mL-1. However, the Se/MSNs exhibited no inhibitory effect on E. coli bacteria. Furthermore, all the samples exhibited excellent cell viability. These studies demonstrate initial in vitro antibacterial activity and good cytocompatibility of Se/MSNs and their potential application in antibacterial nanomedicine.

A novel ordered TiO2 nanodot array on 316LSS (NTA/316LSS) was first prepared by sol-gel in situ growth method. The surface microstructure, chemical components, antibacterial activity and cytocompatibility of the samples were characterized. The results showed that anatase TiO2 nanogranules (45 ± 5 nm) were embedded into nanopits (50 ± 5 nm) and arrayed in an ordered manner. The in vitro antibacterial test showed that there was a 96.3 ± 2.4% reduction in E. coli on the NTA/316LSS surface and a 98.1 ± 1.3% reduction in S. aureus compared to that on untreated 316LSS controls. Furthermore, NTA/316LSS showed good cytocompatibility in vitro. Our study revealed that such TiO2 nanodot surface can be designed to improve the use of 316LSS for various implant application.

Protein-based hydrogels that possess tunable properties have long been a challenge in tissue engineering. Keratin is a group of natural proteins derived from skin and skin appendant, and features a rich content of cysteine residue which exists in the form of disulfide bonds. Inspired by this, in this work, a simple disulfide shuffling strategy was utilized to develop keratin hydrogels by converting the intramolecular disulfide bonds into the intermolecular disulfide bonds. To achieve this, the intramolecular disulfide bonds were first cleaved by the reductive reagent such as cysteine, to liberate free thiol group, which formed intermolecular disulfide bonds through thiol oxidation. It was demonstrated that control of the cysteine level led to a tunable disulfide crosslinking density, and thus an altered network structure, gel degradation, and drug release rate. Also, this strategy enables good biocompatibility of the material owing to avoiding extra chemical crosslinkers in the preparation procedure. Moreover, this keratin hydrogel had redox-responsive capacity in both gel degradation and drug release due to the disulfide-bond based network structure, providing extensive applicability in tissue engineering and drug release.

Based on the linear rheological constitutive model that is used to describe viscoelastic-plastic behavior of viscoelastic materials, a formula of the Poisson’s ratio was deduced according to the relationship between the shear creep compliance and tensile compliance. Instrumented indentation under various loading conditions and universal creep tests were performed on polyamide 12 samples to obtain the relevant rheological parameters. Results show that the Poisson’s ratio for a step load indentation can obtain a constant but overrated value. However, the Poisson’s ratio approaches an asymptotic value and an accurate value can be gained at a certain loading rate.