The extractive membrane bioreactor (EMBR) system combining a membrane process and a biological process has been developed to extract and biodegrade recalcitrant organic pollutants in wastewater. Removal of the organics such as phenol by EMBR requires an effective membrane to selectively extract the organic compounds while rejecting water and other harsh inorganic components. In this work, novel composite membranes consisting of a highly porous substrate, made by tiered polyvinylidene fluoride (PVDF) nanofibers with ultrafine nanofibers on top (61 ± 12 nm in diameter), and a dense polydimethylsiloxane (PDMS) selective layer have been fabricated. We have investigated (1) the effect of the pore size of PVDF nanofibrous substrates, (2) the effect of PDMS preparation method, and (3) the effect of prewetting agent on the resultant composite membranes’ morphologies, mechanical properties, and phenol removal performance. Compared with the symmetric substrate with a nanofiber diameter of 129 ± 13 nm, the tiered substrate can effectively support a uniform and defect-free PDMS coating. This is attributed to the smaller surface pore size of the tiered substrate as a result of its top ultrafine nanofibers. Besides, the use of partially precross-linked PDMS coating solution with increased viscosity and 50 wt % glycerol aqueous solution as the prewetting agent to fill the substrate pores is preferred in order to mitigate PDMS intrusion. On the basis of the resistance model, the overall membrane resistance decreases with the decrease of the PDMS intrusion level, giving rise to a higher overall mass transfer coefficient, k 0, for phenol removal. With the above-mentioned factors being taken into account, the first PDMS-coated PVDF nanofibrous composite membrane has been developed to remove phenol with a high k 0 (over 4 times higher than the existing commercial PDMS tubular membrane) for EMBR. This study provides insights and guidelines for fabricating highly efficient membranes for organic removal in the EMBR process.

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Corneal transplantation is currently the major solution in the treatment of severe corneal diseases. However, it is restricted due to the limited number of corneal donors. A tissue-engineered cornea is a potential substitute which could help overcome this limitation. This research envisages the development of a novel tissue-engineered corneal stroma consisting of bacterial cellulose (BC)/poly(vinyl alcohol) (PVA) hydrogel composites for reconstructing the cornea. It was found that the properties of BC/PVA were better suited for use as a corneal stroma material than the BC hydrogel. The human corneal stromal cells (hCSCs) were used to evaluate the cytotoxicity of the materials, wherein BC/PVA displayed excellent biocompatibility with these cells. Furthermore, in the in vivo studies, the BC/PVA was transplanted intrastromally in rabbits. After four weeks, the cornea remained almost transparent, and without obvious inflammation, sensitization or neovascularization, as confirmed by the clinical and histological examinations. Our results demonstrate that BC/PVA was well-tolerated in the rabbit cornea, and may be a potential substitute for corneal stroma.

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Corneal endothelial disease is a global sight-threatening disease, and corneal transplantation using donor corneas remains the sole therapeutic option. A previous work demonstrated that N (2)-alanyl-glutamine (Ala-Gln) protected against apoptosis and cellular stress, and maintained intestinal tissue integrity. In this pursuit, the present study aimed to examine the effect of Ala-Gln in the protection of the corneal endothelium and expand its range of potential clinical applications. Mice in the control group were intracamerally irrigated with Ringers lactate injection, whereas those in the experimental group were irrigated with Ringers lactate injection containing Ala-Gln. The mean intraocular pressure increased to 44 ± 3.5 mm Hg during intracameral irrigation (normal range 10.2 ± 0.4 mmHg). In vivo confocal microscopy results showed that the addition of Ala-Gln protected the morphology, structure, and density of the corneal endothelial cells. Optical Coherence Tomography (OCT) measurements showed that corneal thickness was not significantly different between the two groups, because of the immediate corneal edema after irrigation, but the addition of Ala-Gln obviously promoted the recovery of the corneal edema. Scanning electron microscopy indicated that the corneal endothelial cells were severely ruptured and exfoliated in the Ringer's group accompanied with cellular edema, when compared with the Ala-Gln group. The intracameral irrigation using Ala-Gln protected the structure and expression of cytoskeleton and Na-K-ATPase, which exhibited a regular distribution and significantly increased expression in comparison to Ringer's group. Furthermore, Ala-Gln maintained the mitochondrial morphology and increased the activity of mitochondria. Moreover, transmission electron microscopy showed that intracameral irrigation of Ala-Gln reversed the ultrastructural changes induced by the acute ocular hypertension in mice. Our study demonstrates that the intracameral irrigation of Ala-Gln effectively maintained the corneal endothelial pump function and barrier function by protecting the mitochondrial function and preventing the rearrangement of cytoskeleton in acute ocular hypertension in mice.