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According to the mechanisms of antimicrobial peptides presented in current research literatures, four cationic peptides rich in arginine residues were designed and synthesized in this study. Their antimicrobial activity to four microorganisms and cytotoxicity to human dermal fibroblasts (HDFs) were evaluated. Among these peptides, PEP-1, PEP-2 and PEP-4 could inhibit and kill these microorganisms at certain concentrations. While PEP-3 only exhibited low inhibition activity against E. coli. PEP-1 rich in arginine residues was more effective against Gram-negative bacteria. PEP-4 with tryptophan and lysine residues in the sequence exhibited enhancement in the antimicrobial activity compared with PEP-3 and presented lowest minimal bactericidal concentration (MBC) to S. aureus and C. albicans in these four peptides. These results indicate that the amount and position of cationic residues in the sequence affects the bactericidal activity and the complement of proline with arginine, tryptophan with arginine and lysine residues would enhance the antimicrobial activity. Moreover, PEP-1, PEP-2 and PEP-4 showed low toxicity at their 1× MBC with no considerable difference with the negative control group in the HDFs cytotoxicity test. This study provides us with a better understanding on the structure-activity relationship, which will be useful for new antimicrobial peptide designs and optimizations. [ABSTRACT FROM AUTHOR]

Infection caused by bacteria in hernia repair site is a severe complication, and patients have to undergo a second surgery to remove the infected prosthesis. In this study, we developed a composite biological safe mesh with antibacterial activity. The composite mesh is composed of large pore polypropylene (PP) mesh, poly-caprolactone (PCL) and antimicrobial peptide (PEP-1), which we synthesized in our lab. Fourier transformed infrared (FTIR) spectroscopy was utilized to analyze the functional groups. The surface morphology, in vitro release characters, mechanical properties, antibacterial activities, and in vitro cytotoxicity of modified mesh were evaluated. Results showed that PEP-1 was loaded in fibers successfully and could diffuse from nanofibers to inhibit bacteria (E. coli) growth. However, the modified mesh did not show inhibition to S. aureus. The mechanical properties of fabricated mesh showed no difference with two commercial surgical meshes. What is more, modified mesh was proved to be nontoxic to human dermal fibroblasts, indicating that this method to fabricate meshes with antibacterial activity is feasible and provides a new strategy for the development of surgical meshes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The GO membrane with short-range vertical pore channels construction strategy. • γ-ray pore-making technology is used to increase the in-plane porosity of GO sheets. • Water moves through the pores in-plane of GO to arrive at the expanded interlayer space. • More in-plane pores and expanded interlayer space lead to enhanced water permeability. • The optimized membrane has a water permeability of 345.23 L m-2h−1 bar−1. Graphene oxide (GO) has the characteristics of easy membrane formation and adjustable interlayer size, which can achieve molecular/ion separation precisely. However, the stacked GO nanosheets have a large tortuosity factor and long mass transfer channel, which limits the feasibility of GO membranes with high-flux. In this study, we propose the short-range pore channels construction strategy that a γ-ray irradiation pore-making technology is used to increase the in-plane porosity of GO nanosheets, thereby shortening the mass transfer channel and realizing the rapid transmission of water molecules. The in-plane defects and d-spacing of GO, used as the mass transfer channel of the membrane, were finely controlled by the irradiation dose of γ-rays. More in-plane pores and expanded interlayer pathway was introduced into the membrane by adjusting the irradiation dose, which leads to significantly strengthened water permeability. The optimized membrane has a higher pure water permeability (345.23 L m-2h−1 bar−1) and dye rejection (nearly 100 %) as well as excellent dye/salt separation performance (α max : 109.27), which is superior to GO membranes previous reported in the literature. The porous membrane with short-range pore channels obtained by high-energy irradiation provides a new strategy for preparing two-dimensional membranes with efficient wastewater purification and recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] Herein, a facile, green, and universal method to prepare polymer fluorescent films was proposed. Firstly, hollow cellulose-based microspheres were prepared by cross-linking copolymerization and self-assembly strategy. Then, after encapsulating the hydrophobic fluorescent dye fluorescein isothiocyanate (FITC) into the cavity of a hollow cellulose-based microsphere through the ultrasonic/dialysis method, a series of flexible fluorescent microsphere films with tunable fluorescence was obtained. The formation of hollow cellulose-based microspheres was confirmed by SEM. DLS, AFM, and UV–vis analysis provided evidences for the successful encapsulation of FITC in hollow cellulose-based microspheres. Benefiting from the synergistic effects of "anchoring", "diluting" and "isolation" for cellulose polymer chain as well as the hollow structure, the aggregation and self-quenching of FITC were effectively inhibited, which promoted the fluorescent films with different loading amount to emit green fluorescence under 365 nm UV light irradiation, and the fluorescence intensity was tunable. Moreover, the fluorescent films exhibited strong UV absorption, excellent optical stability, foldability, and easy scrollability. Particularly, compared with the luminescent film constructed by whisker-like cellulose-based microgel, the hollow cellulose-based fluorescent microsphere film obtained in this work had higher solvent resistance, water contact angle, and thermal stability. Due to the high stability and easy processability of hollow cellulose-based fluorescent microspheres, they could be processed into coating materials and fibers that were durable and widely used. They have potential application value in the fields of light-emitting devices, safety warnings, smart labels, and anti-counterfeiting materials, etc. • The hollow cellulose-based fluorescent microspheres were prepared. • The tunable photoluminescent, water-resistant and flexible films were obtained. • The inhibition mechanism of aggregation-caused quenching (ACQ) effect in fluorescent microsphere films was studied. [ABSTRACT FROM AUTHOR]

Traditional polyamide nanofiltration membranes often can't obtain ideal ion selectivity due to their wide pore size distribution. In this work, a β-cyclodextrin modified sodium hyaluronate (HA-CD) was introduced to achieve the dragging effect of piperazine by non-specific hydrogen bond interaction between HA-CD and substrate and piperazine, thus realizing the purpose of sustained release of piperazine. The MD simulation results demonstrated that the diffusion rate of piperazine was reduced by approximately two orders of magnitude due to the interaction effect. In addition to making the polyamide layer thinner and smoother, HA-CD also narrows the pore size distribution. The salt filtration test showed that the prepared membrane has excellent anion selectivity (α max :114) and permeability (10.66 L m−2 h−1 bar−1). Long-term filtration and nano-scratch test results demonstrated that the prepared membranes have good operational stability (the permeability only decreased about 30%) and mechanical strength (the interface bonding strength increased about 270%). By exploring the effect of the interaction between HA-CD and substrate and piperazine on the interfacial polymerization process, which proved the feasibility of realizing high permeability selectivity and stability of the membrane by constructing the functional bridge between substrates and aqueous monomers. [Display omitted] • Slowing down the diffusion rate of piperazine by dragging effect. • Narrow pore size distribution achieved by the ordered interfacial polymerization reaction. • Grazing-incidence small-angle X-ray scattering for characterization of membrane pore structure. • Polyamide nanofiltration membranes with ultra-high mono- and divalent ion selectivity. • The improved polyamide nanofiltration membrane with excellent stability. [ABSTRACT FROM AUTHOR]