Dual stimuli-responsive polysulfone membranes with interconnected networks by a vapor-liquid induced phase separation strategy.

Dual pH- and thermo-responsive polysulfone (PSf) membranes with three-dimensionally interconnected networks are fabricated by introducing poly(acrylic acid-co-N-isopropylacrylamide) (P(AA-NIPAm)) into the membrane surfaces and pore walls during membrane formation via a vapor-liquid induced phase separation (V-LIPS) process. After introducing the copolymers of P(AA-NIPAm), the fabricated membranes exhibit impressive open network pores on the surfaces, meanwhile their cross-sectional structure turns from classical asymmetric finger-like structure into bi-continuous nanopores throughout the whole thickness of membrane, due to high solution viscosity and low mass transfer rate of VIPS process. Furthermore, pure water permeation tests show that the pure water permeation (Lp) and the molecular weight cutoff (MWCO) of the fabricated PSf/P(AA-NIPAm) membranes increases sharply as the solution pH decreases from 12.5 to 1.5 and the feed temperature increases from 25 to 50 °C, attributing to the increasing pore size. With the decreasing mass ratio of AA to NIPAm, the pH-responsive coefficient decreases, while the temperature- responsive coefficient increases. In particular, for the fabricated membrane with the mass ratio of AA to NIPAm of 3 to 2, Lp changes from ∼16.0 to ∼821.4 L m-2 h-1 bar-1 and MWCO increases from ∼223.1 to ∼1493.2 kDa, as the filtration experiments are operated with feed pH and temperature of 12.5/25 °C and 1.5/50 °C respectively. The results proposed in this study provide a novel mode for design and development dual responsive porous membranes in situ, which will enable good separation of various materials and expand the scope of membrane applications.

Microstructures and performances of pegylated polysulfone membranes from an in situ synthesized solution via vapor induced phase separation approach.

In situ pegylated (PEGylated) microporous membranes have been extensively reported using poly(ethylene glycol) (PEG)-based polymers as blending additives. Alternatively, free standing PEGylated polysulfone (PSf) membranes with excellent hydrophilicity and antifouling ability were directly fabricated from polysulfone/poly(ethylene glycol) methyl ether methacrylate (PSf/PEGMA) solutions after in situ cross-linking polymerization without any treatment via vapor induced phase separation (VIPS) process for the first time. The microstructures and performances of the resulting membranes shifted regularly by adjusting exposure time of the liquid film in humid air. With increasing exposure time, plenty of worm-like networks formed and distributed on membrane surfaces, meanwhile cross-sectional morphology changed from asymmetric finger-like microporous structure to symmetric cellular-like structure, resulting in better mechanical stability. As the exposure time raised from 0 to 5 min, the surface coverage of carboxyl groups increased from ∼1.1 to 4.0 mol%, leading to the decrease in water contact angle from ∼63 to 27° and the increase in water flux from ∼110 to 512 L m-2 h-1. In addition, at prolonged exposure time, increasing hydrophilic PEG chains migrated to membrane surfaced and repelled the adsorption and deposition of protein, resulting in better antifouling ability. The findings of this study offer a facile and high efficient strategy for flexible design and fabrication of the in situ PEGylated membranes with desirable structures and performances in large scale.

Effect of 2-(3-carboxy-1-oxopropyl) amino-2-deoxy-D-glucose on human esophageal cancer cell line.

AIM: To determine whether 2-(3-carboxy-1-oxopropy1) amino-2-deoxy-D-glucose (COPADG), a derivative of D-amino-glucose, inhibited the growth of human esophageal cancer cell line Eca-109. METHODS: Effects of COPADG on Eca-109 cells cultured in RPMI 1640 medium were examined by a tetrazolium-based colorimetric assay (MTT assay). RESULTS: COPADG inhibited the growth of Eca-109 cells in a dose- and time-dependent manner; the maximum inhibition rate was 83.75%. CONCLUSION: COPADG can directly inhibit the proliferation of Eca-109 cells, which may serve as the experimental evidence for development of new drugs for esophageal cancer therapy.

Biomolecule-assisted synthesis of highly stable dispersions of water-soluble copper nanoparticles.

Water-soluble and highly stable dispersions of copper nanoparticles were obtained using a biomolecule-assisted synthetic method. Dopamine was utilized as both reducing and capping agent in aqueous medium. The successful formation of DA-stabilized copper particles was demonstrated by ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), Zeta potential measurement, and Fourier transform infrared spectroscopy (FT-IR). The mechanism of dopamine on the effective reduction and excellent stability of copper nanoparticles was also discussed. This facile biomolecule-assisted technique may provide a useful tool to synthesize other nanoparticles that have potential application in biotechnology.

Effects of {2-[(3-carboxy-1-oxoprogy1)amino]-2-deoxy-D-glucose} on human hepatocellular carcinoma cell line.

AIM: To study the effects of {2-[(3-carboxy-1-oxoprogy1)amino]-2-deoxy-D-glucose (COPADG) on cultured human hepatocellular carcinoma cells (HepG2). METHODS: HepG2 cells were cultured in RPMI-1640 medium. Cell proliferation was determined by MTT assay. Apoptosis was determined by fluorescence microscopy, transmission electron microscopy, agarose gel electrophoresis of DNA fragmentation, and flow cytometry. RESULTS: At the concentration ranging between 1-30 micromol/L, COPADG potently inhibited the growth and induced apoptosis of HepG2 cells. CONCLUSION: COPADG could effectively induce apoptosis in human hepatocellular carcinoma cells. More investigations are warranted for the potential use of this compound as a new agent for the non-surgical management of human hepatocellular carcinoma.