Template-Assisted Fabrication of Thin-Film Composite Forward-Osmosis Membrane with Controllable Internal Concentration Polarization

The internal concentration polarization (ICP) of solutes in the porous substrate layer may reduce the water flux of a forward-osmosis (FO) membrane. Here we present an efficient design by using a novel silica template strategy to address this ICP issue. In particular, a thin-film composite (TFC) FO membrane was prepared by incorporating silica nanoparticles (SiNPs) into the poly­(ether sulfone) (PES) support layer, followed by the removal of the as-encapsulated SiNPs by hydrofluoric acid (HF) etching, leading to the formation of a highly porous and interconnected-pore structure of the support layer. Such porous structure favors the salt back diffusion in the substrate layer, leading to an improved net osmotic pressure across the selective layer. In addition, the HF treatment also contributes to a more hydrophilic top polyamide layer, further improving the performance of the membrane. The effects of the silica template on the morphology and properties of the as-designed TFC FO membrane are systematically investigated, and two major contributors for the enhanced water flux of the membrane have also been identified. The materials and strategy developed in this study will be of potential for the fabrication of high-quality FO membranes

Synergistic Effects of Electrical Stimulation and Aligned Nanofibrous Microenvironment on Growth Behavior of Mesenchymal Stem Cells

Incontrollable cellular growth behavior is a significant issue, which severely affects the functional tissue formation and cellular protein expression. Development of natural extracellular matrix (ECM) like biomaterials to present microenvironment cues for regulation of cell responses can effectively overcome this problem. The external simulation and topological characteristics as typical guiding cues are capable of providing diverse influences on cellular growth. Herein, we fabricated two-dimensional aligned conductive nanofibers (2D-ACNFs) by an electrospinning process and surface polymerization, and the obtained 2D-ACNFs provided the effects of both alignment and electrical stimulation (ES) on cellular response of human mesenchymal cells (hMSCs). The results of cellular responses implied that the obtained 2D-ACNFs could offer a synergistic effect of both ES and aligned nanopattern on hMSC growth behavior. The effects could not only promote hMSCs to contact each other and maintain cellular activity but also provide positive promotion to regulate cellular proliferation. Thus, we believe that the obtained 2D-ACNFs will have a broad application in the biomedical field, such as cell culture with ES, directional induction for cell growth, and damaged tissue repair, etc

Surface Reaction Route To Increase the Loading of Antimicrobial Ag Nanoparticles in Forward Osmosis Membranes

Biofilm formation from bacterial growth and colonization is a known cause for membrane performance deterioration in water treatment. A broad-spectrum biocide such as silver nanoparticles (Ag NPs) is generally added to the membrane to impart biofilm resistance. Because biofilm formation begins with the membrane surface in contact with the feedwater, a high loading of uniformly dispersed Ag nanoparticles (Ag NPs) on the membrane exterior surface is desirable for a good antimicrobial performance. This was accomplished in this work by a short alkaline treatment of a hydrolyzable membrane (polyacrylonitrile, PAN) to introduce negative charge to the surface. A subsequent exposure to a Ag precursor solution followed by reduction under mild reducing condition (CO) limited the Ag NP deposition to within a narrow region of the membrane surface. The Ag content on the resultant membrane exterior surface in this study was also the highest in the literature. Different from previously reported methods, this method of Ag NP incorporation can be applied to thin film composite (TFC) membranes without any adverse effect on the water flux. The TFC membranes modified as such have shown good antibacterial resistance for 14 days under laboratory conditions optimized for the growth of Escherichia coli

Celastrol-based nanomedicine hydrogels eliminate posterior capsule opacification - Supplementary table

Aim: To formulate an injectable thermosensitive micelle–hydrogel hybrid system loaded with celastrol (celastrol-loaded micelle hydrogel: CMG) to prevent posterior capsule opacification (PCO). Materials & methods: Celastrol-loaded micelles were embedded in a thermosensitive hydrogel matrix to enable controlled on-demand celastrol delivery into the residual capsule. The efficacy and mechanisms of the system for eliminating PCO were evaluated in rabbits. Results: Celastrol-loaded micelles inhibited the migration and proliferation of lens epithelial cells induced by TGF-β1. Celastrol prevents epithelial– mesenchymal transition in lens epithelial cells induced by TGF-β1 through the TGF-β1/Smad2/3/TEAD1 signaling pathway. In vivo efficiency evaluations showed that CMG demonstrated an excellent inhibitory effect on PCO in rabbits and had no obvious tissue toxicity. Conclusion: Injectable CMG may represent a promising ophthalmic platform for preventing PCO. This versatile injectable micelle–hydrogel hybrid represents a clinically relevant platform to achieve localized therapy and controlled release of drugs in other disease therapies.</p

An Effective Design of Electrically Conducting Thin-Film Composite (TFC) Membranes for Bio and Organic Fouling Control in Forward Osmosis (FO)

The organic foulants and bacteria in secondary wastewater treatment can seriously impair the membrane performance in a water treatment plant. The embedded electrode approach using an externally applied potential to repel organic foulants and inhibit bacterial adhesion can effectively reduce the frequency of membrane replacement. Electrode embedment in membranes is often carried out by dispensing a conductor (e.g., carbon nanotubes, or CNTs) in the membrane substrate, which gives rise to two problems: the leaching-out of the conductor and a percolation-limited membrane conductivity that results in an added energy cost. This study presents a facile method for the embedment of a continuous electrode in thin-film composite (TFC) forward osmosis (FO) membranes. Specifically, a conducting porous carbon paper is used as the understructure for the formation of a membrane substrate by the classical phase inversion process. The carbon paper and the membrane substrate polymer form an interpenetrating structure with good stability and low electrical resistance (only about 1Ω/□). The membrane-electrode assembly was deployed as the cathode of an electrochemical cell, and showed good resistance to organic and microbial fouling with the imposition of a 2.0 V DC voltage. The carbon paper-based FO TFC membranes also possess good mechanical stability for practical use

M2 macrophages promote subconjunctival fibrosis through YAP/TAZ signalling

To evaluate the role of M2 macrophages in subconjunctival fibrosis after silicone implantation (SI) and investigate the underlying mechanisms. A model of subconjunctival fibrosis was established by SI surgery in rabbit eyes. M2 distribution and collagen deposition were evaluated by histopathology. The effects of M2 cells on the migration (using wound-scratch assay) and activation (by immunofluorescence and western blotting) of human Tenon’s fibroblasts (HTFs) were investigated. There were more M2 macrophages (CD68+/CD206+ cells) occurring in tissue samples around silicone implant at 2 weeks postoperatively. Dense collagen deposition was observed at 8 weeks after SI. In vitro experiment showed M2 expressed high level of CD206 and transforming growth factor-β1 (TGF-β1). The M2-conditioned medium promoted HTFs migration and the synthesis of collagen I and fibronectin. Meanwhile, M2-conditioned medium increased the protein levels of TGF-β1, TGF-βR II, p-Smad2/3, yes-associated protein (YAP), and transcriptional coactivator with PDZ-binding motif (TAZ). Verteporfin, a YAP inhibitor, suppressedTGF-β1/Smad2/3-YAP/TAZ pathway and attenuated M2-induced extracellular matrix deposition by HTFs. TGF-β1/Smad2/3-YAP/TAZ signalling may be involved in M2-induced fibrotic activities in HTFs. M2 plays a key role in promoting subconjunctival fibrosis and can serve as an attractive target for anti-fibrotic therapeutics.</p

Antibiotic-free Self-assembled Polypeptide Nanomicelles for Bacterial Keratitis

Drug resistance of bacteria limits the effectiveness of traditional antibiotics for bacterial keratitis. Antimicrobial peptides with a broad-spectrum antibacterial activity and bactericidal mechanism of membrane disruption provide an alternative for the treatment of bacterial keratitis. In the present study, an antimicrobial peptide polymer was developed and self-assembled into polypeptide nanomicelles (PPNMs) for treatment of bacterial keratitis. The self-assembly process led to spherical shapes with a diameter of around 45 nm and a relatively narrow size distribution. The nanomicelles also exhibited a positive charge and excellent biocompatibility. Antimicrobial tests have shown that PPNMs possessed a mechanism of action to destroy bacterial membranes and were superior to tobramycin in the treatment of bacterial keratitis. Therefore, we expect PPNMs to have good potential as an antimicrobial drug

Intracellular drug delivery and release efficiency measurements.

<p>Quantitative analysis of FDA-positive LoVo cells by flow cytometry after incubation with FDA-SPIO-PEALCa (A). Confocal laser scanning microscopy (CLSM) images (1000 ×) of LoVo cells after treated with FDA-SPIO-PEALCa (B). The lysosomes and nuclei were stained by red and blue fluorescent probe, respectively. <i>In vitro</i> FDA released from PEALCa micelle at 37 °C in HCl (pH 5.0) and PBS (pH 7.4) (C).</p

Tumor targeting evaluation <i>in vivo</i>.

<p>Group 1: mice with LoVo tumors prior and after injection of blank PEALCa; Group 2: mice with LoVo tumors prior and after injection of SPIO-PEALCa (A). The relative T2 value of both groups prior and after injection(B). Prussian blue staining images of the tumor histological sections treated with PTX-PEALCa and PTX-SPIO-PEALCa (200 ×) (C).</p

Cytotoxicity and cell apoptosis evaluation.

<p><i>In vitro</i> cytotoxicity of various concentrations of PEALCa and SPIO-PEALCa in LoVo cells detected by MTT assay (A). MTT assay of the cytotoxicity of PTX-SPIO-PEALCa and free Taxol with different PTX concentrations (B). LoVo cell apoptosis detected by <i>TUNEL</i> assay after PTX-SPIO-PEALCa incubation with different PTX concentrations (50×) (C). Magnified image of the red rectangular represents the representative normal or apoptotic cell.</p