Reversibly Cross-Linked Isoporous Membranes Fabricated by the Recyclable Block Copolymer with Pendent Dithiolane Groups.

The reversible formation and cleavage of disulfide bonds under physical/chemical stimuli make it a valuable motif in constructing dynamically cross-linked materials. In the present work, the block copolymer bearing pendent dithiolanes was synthesized and fabricated into isoporous membranes by the combination of self-assembly and nonsolvent-induced phase separation strategy. The cross-linking within the membrane was realized by the thiol-initiated ring-opening cascades of cyclic disulfides. Successful formation of disulfide bond networks within the isoporous membranes was proved by the Raman spectra, UV-vis diffuse reflectance spectroscopy, differential scanning calorimetry, and rheological analysis. The cross-linking in membranes was further demonstrated by the notably improved toughness and obviously enhanced swelling resistance to acid/alkaline solution as well as organic solvents. Importantly, the cross-linked isoporous membranes were fully dissolvable in solution containing dithiothreitol, which enabled the complete cleavage of disulfide bonds and successful recovery of the block copolymer that was able to be repeatedly fabricated into isoporous membranes with pore sizes identical to membranes prepared from the freshly synthesized copolymer. Our results indicate that dynamically cross-linked isoporous membranes with improved durability and good recyclability can be custom-made by simply incorporating active dithiolane moieties into self-assembling block copolymers.

Hyper-crosslinked Isoporous Block Copolymer Membranes with Robust Solvent Resistance and Customized Pore Sizes for Precise Separation.

Isoporous block copolymer membranes are viewed as the next-generation separation membranes for their unique structures and urgent application in precise separation. However, an obvious weakness for such membranes is their poor solvent-resistance which limits their applications to aqueous solution, and isoporous membranes with superior solvent-resistance and tunable pore size have been rarely prepared before. Herein, self-supporting isoporous membranes with excellent solvent resistance are prepared by the facile yet robust hyper-crosslinking approach which is able to create a rigid network in whole membranes. The hyper-crosslinking is found to be a novel and non-destructive approach that does not change pore size and isoporous structure during the reaction, and the resulting hyper-crosslinked isoporous membranes display superior structural and separation stability to a broad range of solvents with varied polarities for months to years. More importantly, hyper-crosslinking has proved to be a universal strategy that is applicable to isoporous membranes with varied pore size and pore chemistry, offering an important opportunity to prepare solvent-resistant isoporous membranes with customizable pore size and pore functionality that are important to realize their accurate separations in organic solvents. This concept is demonstrated finally by precise and on-demand separation of nanoparticles with the prepared membranes.

Nanovoid Membranes Embedded with Hollow Zwitterionic Nanocapsules for a Superior Desalination Performance.

In order to lower the capital and operational cost of desalination and wastewater treatment processes, nanofiltration (NF) membranes need to have a high water permeation and ionic rejection, while also maintaining a stable performance through antifouling resistance. Recently, Turing-type reaction conditions [ Science 2018, 360, 518-521] and sacrificed metal organic frame (MOF) nanoparticles [ Nat. Commun. 2018, 9, 2004] have been reported to introduce nanovoids into thin-film composite (TFC) polyamide (PA) NF membranes for an improved performance. Herein, we report a one-step fabrication of thin-film nanocomposite membranes (TFNM) with controllable nanovoids in the polyamide layer by introducing hollow zwitterionic nanocapsules (HZNCs) during interfacial polymerization. It was found that embedding HZNCs increases the membrane internal free volume, external surface area, and hydrophilicity, thus enhancing the water permeation and antifouling resistance without trading off the rejection of multivalent ions. For example, water permeation of the NF membranes embedded with about 19.0 wt % of HZNCs (73 L m-2 h-1) increased by 70% relative to the value of the control TFC NF membrane without HZNCs (43 L m-2 h-1). This increase comes while also maintaining 95% rejection of Na2SO4. Further, we also determined the effect of the mass loading of HZNCs on the top surface of the TFC NF membranes on the membrane performance. This work provided a direct and simple route to fabricate advanced desalination membranes with a superior separation performance.

Chemical constituents from the stems of Machilus philippinensis Merr. and the neuroprotective activity of cinnamophilin.

The Machilus genus (Lauraceae) had been extensively utilized in folk medicine due to its broad range of bioactivities. In the present study, a series of chromatographic separations of the methanol extract of stems of M. philippinensis led to the identification of thirty eight compounds totally. Among these, biscinnamophilin (1), machilupins A-C (2-4), machilutone A (5), and machilusoxide A (6) were new compounds reported for the first time. In addition, 5 was characterized with a unprecedented carbon skeleton. Other known compounds, including the major compounds cinnamophilin (7) and meso-dihydroguaiaretic acid (8), are identified by comparison of their physical and spectroscopic data with reported values. One of the reported compounds, cinnamophilin A (10), should be revised as dehydroguaiaretic acid (9) after careful comparison of all the 1H and 13C NMR data. Moreover, the neuroprotective activity of cinnamophilin (7) was examined in a primary cortical neuron culture and the results indicated that 7 was effective against glutamate induced excitotoxicity.

Ion Exchange and Antibiofouling Properties of Poly(ether sulfone) Membranes Prepared by the Surface Immobilization of Brønsted Acidic Ionic Liquids via Double-Click Reactions.

Brønsted acidic ionic liquids (BAILs) are unique ionic liquids that display chemical structures similar to zwitterions, and they were typically used as solvents and catalysts. In this work, an imidazole-based BAIL monolayer was fabricated onto poly(ether sulfone) (PES) membranes via surface clicking reactions, and the multifunctionality, including ion exchange and biofouling resistance to proteins and bacteria, was demonstrated, which was believed to be one of few works in which BAIL had been considered to be a novel fouling resistance layer for porous membranes. The successful immobilization of the BAILs onto a membrane surface was confirmed by X-ray photoelectron spectroscopy analysis, contact angle measurement, and ζ potential determination. The results from Raman spectroscopy showed that, as a decisive step prior to zwitterion, the BAIL was deprotonated in aqueous solution, and biofouling resistance to proteins and bacteria was found. However, BAIL displayed ion exchange ability at lower pH, and surface hydrophilicity/hydrophobicity of membranes could be tuned on purpose. Our results have demonstrated that the BAIL grafted onto membranes will not only act as an antibiofouling barrier like zwitterions but also provide a platform for surface chemical tailoring by ion exchange, the property of which will become especially important in acidic solutions where the fouling resistance performances of zwitterions are greatly weakened.

Versatile antifouling polyethersulfone filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive.

Here we describe the development of versatile antifouling polyethersulfone (PES) filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive. Amphiphilic polyethersulfone-block-poly(2-hydroxyethyl methacrylate) (PES-b-PHEMA) was beforehand designed and used as the blending additive of PES membranes prepared by phase inversion technique. The surface enriched PHEMA blocks on membrane surface acted as an anchor to immobilize the initiating site. Poly(sulfobetaine methacrylate) (PSBMA) were subsequently grafted onto the PES blend membranes by surface-initiated atom transfer radical polymerization (SI-ATRP). The analysis of surface chemistry confirmed the successful grafting of zwitterionic PSBMA brushes on PES membrane surface. The resulted PES-g-PSBMA membranes were capable of separating proteins from protein solution and oil from oil/water emulsion efficiently. Furthermore, the modified membranes showed high hydrophilicity and strongly antifouling properties due to the incorporation of well-defined PSBMA layer. In addition, the PES-g-PSBMA membranes exhibited excellent blood compatibility and durability during the washing process. The developed antifouling PES membranes are versatile and can find their applications in protein filtration, blood purification and oil/water separation, etc.

Correlation between three-dimensional ultrasound features and pathological prognostic factors in breast cancer.

OBJECTIVES: To investigate the correlation of three-dimensional (3D) ultrasound features with prognostic factors in invasive ductal carcinoma. METHODS: Surgical resection specimens of 85 invasive ductal carcinomas of 85 women who had undergone 3D ultrasound were included. Morphology features and vascularization perfusion on 3D ultrasound were evaluated. Pathologic prognostic factors, including tumour size, histological grade, lymph node status, oestrogen and progesterone receptor status (ER, PR), c-erbB-2 and p53 expression, and microvessel density (MVD) were determined. Correlations of 3D ultrasound features and prognostic factors were analysed. RESULTS: The retraction pattern in the coronal plane had a significant value as an independent predictor of a small tumour size (P = 0.014), a lower histological grade (P = 0.009) and positive ER or PR expression status (P = 0.001, 0.044). The retraction pattern with a hyperechoic ring only existed in low-grade and ER-positive tumours. The presence of the hyperechoic ring strengthened the ability of the retraction pattern to predict a good prognosis of breast cancer. The increased intra-tumour vascularization index (VI, the mean tumour vascularity) reflected a higher histological grade (P = 0.025) and had a positive correlation with MVD (r = 0.530, P = 0.001). CONCLUSIONS: The retraction pattern and histogram indices of VI provided by 3D ultrasound may be useful in predicting prognostic information about breast cancer. KEY POINTS: Three-dimensional ultrasound can potentially provide prognostic evaluation of breast cancer. The retraction pattern and hyperechoic ring in the coronal plane suggest good prognosis. The increased intra-tumour vascularization index reflects a higher histological grade. The intra-tumour vascularization index is positively correlated with microvessel density.

Hemocompatible and antibacterial porous membranes with heparinized copper hydroxide nanofibers as separation layer.

Here we report the fabrication of a novel heparinized copper hydroxide (Cu(OH)2) nanofiberous membrane with satisfying hemocompatibility and antibacterial properties. The positively charged Cu(OH)2 nanofibers were prepared in a weakly alkaline copper nitrate solution in the presence of 2-aminoethanol. A heparin (Hep) solution was then added dropwise into the solution of nanofibers to immobilize negatively charged heparin onto the Cu(OH)2 nanofibers by electrostatic interaction. A composite Hep@Cu(OH)2 nanofiberous membrane was prepared by filtration and deposition of the heparinized nanofibers onto a polysulfone (PSF) porous membrane. Chemical composition analysis of membrane surface using X-ray photoelectron spectroscopy (XPS) confirmed the successful immobilization of heparin on Cu(OH)2 nanofibers. The amount of immobilized heparin on nanofiberous membrane was determined by a colorimetric assay of toluidine blue dye and the results showed that the amount of immobilized heparin was strongly dependent on the heparin dosage in reaction solution. The results of contact angle measurement indicated that the hydrophilicity of Cu(OH)2 nanofiberous membranes was enhanced by the immobilization of heparin. The adhesion, activation and transmutation of platelets on Hep@Cu(OH)2 membrane were suppressed remarkably due to the introduction of heparin, which suggested that the Hep@Cu(OH)2 membranes had good hemocompatibility. In addition, Cu(OH)2 and Hep@Cu(OH)2 nanofiberous membranes exhibited very good antibacterial activities against Escherichia coli and Staphyloccocus aureus.

Clinical evaluation of relationship between dry eye and bubbles in the inferior conjunctiva fornix / 中华实验眼科杂志

Background Instability of tear film,increase of ocular surface temperature and tear evaporation are the associated factors of both bubbles and dry eye.But the relationship between dry eye and ocular surface bubbles is unclear.The bubbles are easily retained and checked in the inferior conjunctiva fornix.Objective This study aimed to study the relationship between dry eye and bubbles in the inferior conjunctiva fornix.Methods Sixty-four eyes of 32 patients with binocular irritative symptoms and bubbles or without bubbles in the inferior conjunctiva fornix were collected in Affiliated Tianyou Hospital of Wuhan University of Science and Technology from January to May,2012.The bubbles in the inferior conjunctiva fornix were examined by slit lamp microscope,and the break-up time (BUT) and Schirmer Ⅰ test (S Ⅰ t) were performed.The differences of BUT and S Ⅰ t between the two groups were compared using independent sample t test,and abnormality rate of examination indexes was statistical analyzed by CHI-Square test using a SPSS 11.5 software.Written informed consent was obtained prior to the clinical survey.Results In the 64 eyes of the bubbles group,incidence of dry eye was 75.00％,and the incidence of both BUT＜5 seconds and S Ⅰ t＜5 mm/5 minutes was 46.88％ ;while the incidence of BUT＜5 seconds or S Ⅰ t＜5 mm/5 minutes was 53.13％ and 57.81％,respectively.In 64 eyes without bubbles,incidence of dry eye was 31.25％,the incidence of both BUT＜5 seconds and S Ⅰ t＜5 mm/5 minutes was 18.75％,that of BUT＜5 seconds or S Ⅰ t＜5 mm/5 minutes was 21.88％ and 20.31％,respectively.The incidences of dry eye,both BUT＜5 seconds and S Ⅰ t＜5 mm/5 minutes,BUT ＜5 seconds,S Ⅰ t＜5 mm/5 minutes were significantly higher in the bubbles group than those of the without bubbles group (all at P=0.00).In the 68 eyes determined as dry eyes,48 eyes (48/68) were in the bubbles group and 20eyes (20/68) were in the without bubbles group,showing a significant difference between the two groups (x2 =24.60,P＜0.01).The incidences of both BUT＜5 seconds,S Ⅰ t＜5 mm/5 minutes were not significantly different between the two groups (x2 =0.01,P=0.95;x2 =1.06,P=0.30).Conclusions The bubbles in the inferior conjunctiva fornix is highly correlated with dry eye.