A simple approach to constructing antibacterial and anti-biofouling nanofibrous membranes

<div><p>In this work, antibacterial and anti-adhesive polymeric thin films were constructed on polyacrylonitrile (PAN) nanofibrous membranes in order to extend their applications. Polyhexamethylene guanidine hydrochloride (PHGH) as an antibacterial agent and heparin (HP) as an anti-adhesive agent have been successfully coated onto the membranes <i>via</i> a layer-by-layer (LBL) assembly technique confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), energy-dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The antibacterial properties of LBL-functionalized PAN nanofibrous membranes were evaluated using the Gram-positive bacterium <i>Staphylococcus aureus</i> and the Gram-negative <i>Escherichia coli.</i> Furthermore, the dependence of the antibacterial activity and anti-biofouling performance on the number of layers in the LBL films was investigated quantitatively. It was found that these LBL-modified nanofibrous membranes possessed high antibacterial activities, easy-cleaning properties and stability under physiological conditions, thus qualifying them as candidates for anti-biofouling coatings.</p></div

Key issues in the design and delivery of learning and teaching

<p>Data show the average OD values of each group with standard deviations at 1∶100 serum dilution. The serum samples were collected at 4 weeks after the 3^rd DNA immunization prior to challenge. Statistical differences are indicated by <i>p</i> values.</p

Morphology Design of IRMOF‑3 Crystal by Coordination Modulation

A one-pot synthesis design on shape-controlled growth of Zn-based isoreticular metal–organic framework (i.e., IRMOF-3) was carried out in this work with the controllable crystal morphological evolution from simple cubes to several complex shapes. A new synthetic protocol was devised where poly­(vinylpyrrolidone) (PVP), noble metal source (AgNO₃), mixed solvents (<i>N</i>,<i>N</i>-dimethylformamide (DMF)–ethanol mixture) and tetramethylammonium bromide (TMAB) were mutually introduced to the reaction medium as surfactant, adjuvant, accelerator, and structure-directing agent (SDA), respectively. Meanwhile, the crystallization process was investigated by a series of time-dependent experiments. Indeed, the added modulators and crystallization time were able to regulate the growth and thus the morphology of the final products. The resulting homogeneous IRMOF-3-Ag-<i><b>n</b></i> materials with unique and novel crystal morphologies were characterized via scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermogravimetric and differential thermal analyses (TG-DTA), transmission electron microscopy (TEM), infrared spectrum (IR), and optical microscope characterizations. Various shapes of IRMOF-3-Ag-<i><b>n</b></i> crystals as sorbents for capturing dibenzothiophene (DBT) were evaluated. Among all the morphology-controlled samples, IRMOF-3-Ag-<b>5</b> with hollow sphere morphology was demonstrated to show the highest DBT capture capacity due to its unique morphology

Size of plasmid DNA and PAMAM-Lys complexes.

<p>SEM photograph of plasmid DNA (x50,000) (A) compound PAMAM G4.0/DNA (R_+/− = 2; ×40,000) (B) and compound PAMAM-Lys/DNA (R_+/− = 4; ×80,000) (C).</p

SjC23-specific cytokine responses in splenocytes induced by DNA vaccines,PAMAM-lys, PAMAM-lys/vaccines and empty vector.

<p>Data show IL-2, IFN–γ and TNF responses with SjC23 stimulation or blank control. The splenocytes were collected at 3 weeks after the 3rd DNA immunization.</p

Comparison of recovered adult worms in each group.

<p>Data are presented as mean ±SD, n = 12–13;</p><p>Worm reduction rate of each group is calculated by comparing with control group.</p

Agarose gel electrophoresis retardation assay of plasmid DNA byPAMAM4.0G (A), PAMAM 5.0G(B), and PAMAM-Lys(C).

<p>Plasmid DNA (0.5 µg) only (lane 1); charge ratio of polymer/DNA = 0.5, 1, 2, 4, 8 and 10 (lanes 2, 3, 4, 5, 6, and 7, respectively).</p

efficiency of PAMAM-Lys - 5.0G PAMAM complex determined by flow cytometry in 293T cells.

<p>Each data point represents the mean ± standard deviation (n = 3). At 48 h following transfection, cells were collected and the percentage of transfected cells was determined by measuring EGFP fluorescence (488 nm).</p

Cytotoxicity assay in 293T cells PLL (▪), PAMAM5.0G (•), PAMAM-Lys (▾), PAMAM4.0 (▴).

<p>Each DNA complex was incubated with the cells for 24± standard deviation of the number of live cell every 100 cells. <i>*p<0.05.</i></p

One-Pot Synthesis of Ternary Pt–Ni–Cu Nanocrystals with High Catalytic Performance

Shape-controlled synthesis of multicomponent metal nanocrystals (NCs) bounded by high-index facets (HIFs) is of significant importance in the design and synthesis of highly active catalysts. It is a highly challenging task to design and synthesize ternary alloy NCs with HIFs due to the formidable difficulties in controlling the nucleation/growth kinetics of NCs in the presence of three metal precursors with different reduction potentials. We report herein, for the first time, the preparation of Pt–Ni–Cu alloy NCs by tuning their shape from crossed, dendritic, concave nanocubic (CNC) to rough octahedral (ROH) NCs through a facile one-pot solvothermal synthesis method. Specifically, the crossed and CNC Pt–Ni–Cu alloy NCs are bounded by high-index {<i>hk</i>0} facets and ROH with rich lattice defects. The electrocatalytic activities of these Pt–Ni–Cu alloy NCs toward methanol and formic acid oxidation were tested. It was shown that these Pt–Ni–Cu alloy NCs exhibited enhanced activity and stability compared to commercial Pt black and Pt/C catalysts as well as previous Pt–Ni and Pt CNCs under the same reaction conditions, demonstrating the superior electrocatalytic activity of Pt–Ni–Cu ternary alloys compared to monometal and binary Pt–Ni NCs. Surprisingly, we have found that the Pt–Ni–Cu ROH NCs have exhibited a higher specific catalytic activity than the crossed and CNC Pt–Ni–Cu alloy NCs with HIFs. The electronic and structure effects have been extensively discussed to shed light on the excellent electrocatalytic performance of Pt–Ni–Cu ROH NCs