Transformation of Fibrous Membranes from Opaque to Transparent under Mechanical Pressing

There is a great demand for transparent films,membranes,or substrates in the fields of intelligent wearables,electronic skins,air filtration,and tissue engineering.Traditional materials such as glass and plastics cannot satisfy these requirements because of the lack of interconnected pores,undesirable porosity,and flexibility.Electrospun fibrous membranes offset these shortcomings because they contain small pores and have high porosity as well as outstanding flexibility.Thus,the development of transparent electrospun fibrous membranes is of great value.This work reports a simple and effective way to develop flexible and porous transparent fibrous membranes(TFMs)directly from electrospun fibrous membranes via mechanical pressing,without employing any other additives.In addition,the relationship between the transparency performance and the molecular structure of the polymers after pressing was summarized for the first time.After mechanical pressing,the membranes maintained fibrous morphology,micron-sized pores,and desired porosity.Polystyrene fibrous membranes,which exhibited excellent optical and mechanical properties,were used as a reference.The TFMs possessed high transparency(~89%visible light transmittance at 550 nm),high porosity(10%–30%),and strong mechanical tensile strength(~148 MPa),nearly 78 times that of the pristine electrospun fibrous membranes.Moreover,this study demonstrated that transparent and conductive membranes can be fabricated based on TFMs using vacuum-assisted filtration of silver nanowires followed by mechanical pressing.Compared with indium tin oxide films,conductive TFMs exhibited good electrical conductivities(9Ωper square(Ω·sq^(−1)),78%transmittance at 550 nm)and notable mechanical performance(to bear abundant bending stresses).

ELECTROSPINNING OF ZEIN/CHITOSAN COMPOSITE FIBROUS MEMBRANES

Zein/chitosan composite fibrous membranes were fabricated from aqueous ethanol solutions by electrospinning. Poly（vinyl pyrrolidone） （PVP） was introduced to facilitate the electrospinning process of zein/chitosan composites. The asspun zein/chitosan/PVP composite fibrous membranes were characterized by scanning electron microscopy （SEM） and tensile tests. SEM images indicated that increasing zein and PVP concentrations led to an increase in average diameters of the composite fibers. In order to improve stability in wet stage and mechanical properties, the composite fibrous membranes were crosslinked by hexamethylene diisocyanate （HDI）. The crosslinked composite fibrous membranes showed slight morphological change after immersion in water for 24 h. Mechanical tests revealed that tensile strength and elongation at break of the composite fibrous membranes were increased after crosslinking, whereas Young＇s modulus was decreased.

Molecular Imprinting Fibrous Membranes of Poly(acrylonitrile-co-acrylic acid) Prepared by Electrospinning

IntroductionOver the past few decades, molecular imprinting has been described as a technology for preparing ＂molecular doors＂ which can be matched to ＂template keys＂. It has been found to be a simple and effective approach to introduce specific recognition sites into synthetic polymers, namely, to create molecular imprinting polymers Remarkable features such as stability, ease of preparation and low cost, have made molecular imprinting polymers particularly attractive in chemical sensors, catalysis, drug delivery, and dedicated separations. Practical applications of molecular imprinting polymers require accessible sites, fast mass transfer, and quick binding. However, present techniques used to prepare molecular imprinting polymers most often result in materials exhibiting a high affinity and selectivity but a low capacity and poor site accessibility for the target molecules. It is also very difficult to remove the imprinted molecules located in these molecular imprinting polymers because the highly cross-linked structures do not allow the templates to move freely. To some extent, combining molecular imprinting technology with membrane separation and surface imprinting can overcome the shortcomings, such as mass transfer limitations and non-quantitative recovery of the template molecules seen for imprinted materials fabricated by conventional bulk methods. In that ease, it appears to us that molecular imprinting polymers with high surface area to volume ratios are particularly desirable for largescale applications. Eleetrospun nano and ultrafine fibrous membranes are the most suitable materials due to advantages such as： （1） large specific surfaces, providing relatively high imprinting sites per unit mass; （2） fine porous structures, resulting in the accessibility of imprinting sites and low diffusion resistance necessary for high efficiency; and （3） easy recoverability from practical operation or applicability for continuous usages. Therefore, in this work, we prepared a unique kind of imprinted material--molecularly imprinted fibrous membranes of poly （ acrylonitrile-co-acrylic acid） fabricated by means of an electrospinning process.

Cerium oxide nanoparticles loaded nanofibrous membranes promote bone regeneration for periodontal tissue engineering

Bone regeneration is a crucial part in the treatment of periodontal tissue regeneration,in which new attempts come out along with the development of nanomaterials.Herein,the effect of cerium oxide nanoparticles(CeO_(2)NPs)on the cell behavior and function of human periodontal ligament stem cells(hPDLSCs)was investigated.Results of CCK-8 and cell cycle tests demonstrated that CeO_(2)NPs not only had good biocompatibility,but also promoted cell proliferation.Furthermore,the levels of alkaline phosphatase activity,mineralized nodule formation and expressions of osteogenic genes and proteins demonstrated CeO_(2)NPs could promote osteogenesis differentiation of hPDLSCs.Then we chose electrospinning to fabricate fibrous membranes containing CeO_(2)NPs.We showed that the composite membranes improved mechanical properties as well as realized release of CeO_(2)NPs.We then applied the composite membranes to in vivo study in rat cranial defect models.Micro-CT and histopathological evaluations revealed that nanofibrous membranes with CeO_(2)NPs further accelerated new bone formation.Those exciting results demonstrated that CeO_(2)NPs and porous membrane contributed to osteogenic ability,and CeO_(2)NPs contained electrospun membrane may be a promising candidate material for periodontal bone regeneration.

Sorption of triclosan on electrospun fibrous membranes: Effects of pH and dissolved organic matter

Three hydrophobic and polyporous electrospun fibrous membranes(EFMs)were prepared by electrospinning methoxy polyethylene glycol-poly(lactide-co-glycolide)(MPEG-PLGA),poly(D,L-lactide-co-glycolide)(PLGA)and poly(D,L-lactide)(PDLLA).The effects of pH and dissolved organic matter(DOM)on triclosan(TCS)sorption by EFMs in aqueous solution were investigated.The results indicated that hydrogen bonding,hydrophobic and π-π bonding interactions led to fast adsorption,which governed the adsorption rates of TCS onto EFMs.The maximum sorption capacities of MPEG-PLGA,PLGA and PDLLA reached 130,93 and 99 mg g^-1,respectively,which were in positive correlation with their pore volumes and influenced by pore filling processes.The solution pH could significantly influence the TCS sorption by EFMs.In acid condition,protonated TCS facilitated their sorption onto EFMs.No obvious sorption was observed in alkaline condition due to repulsive forces between negatively charged EFMs and deprotonated TCS(pKa=7.9).The presence of DOM inhibited TCS sorption onto EFMs due to competitive adsorption.The results could be due to the occupation of the adsorption sites and the blockage of the pore entrance by DOM.

SEPARATION OF THORIUM FROM YTTERBIUM WITH CYANEX272 BY USING A HOLLOW FIBER MEMBRANE EXTRACTOR

The based membrane extraction of Th(IV) and Yb(III) was studied with HBTMPP in heptane. The separation process of Th(IV) and Yb(III) was considered to be a kinetics competition one. The separation for the mixture of Th(IV) and Yb(III) was carried out by successive membrane extraction and stripping simultaneously. The concentration ratio of Th(IV) and Yb(III) is 16.74 in the stripping solution. The recovery of Th(IV) is 71.6%. The purity of Th(IV) is 95.74%. The separation factor of Th(IV) and Yb(III) is 2.52×106, which was obtained by interfacial kinetics.

Bilateral malignant glaucoma with bullous keratopathy:A case report

BACKGROUND Malignant glaucoma,caused by aqueous misdirection,is a challenging postsurgical complication presented with normal/high intraocular pressure and shallowing of the central and peripheral anterior chambers.Its incidence is about 0.6%-4.0%.It can be secondary to filtering surgeries,laser iridotomy,and cataract surgery.Short axial length and a history of angle closure glaucoma are its main risk factors.Here,we report a bilateral malignant glaucoma with bullous keratopathy in the patient’s left eye.CASE SUMMARY We present a case of bilateral malignant glaucoma.The cause of malignant glaucoma for each eye of this patient was different.Hence,the management strategy and selection of surgical methods were also different.However,the normal anterior chamber was ultimately maintained,and maximum visual function was preserved.Even though the left eye received multiple surgeries and corneal endothelial decompensation occurred,the formation of a retroendothelial fibrous membrane partially compensated for the function of the corneal endothelium.CONCLUSION The formation of a retroendothelial fibrous membrane partially compensated for the function of the corneal endothelium.

Microbiome-friendly PS/PVP electrospun fibrous membrane with antibiofilm properties for dental engineering

Dental caries is one of the most prevalent and biofilm-associated oral diseases in humans.Streptococcus mutans,with a high ability to form biofilms by adhering to hard surfaces,has been established as an important etiological agent for dental caries.Therefore,it is crucial to find a way to prevent the formation of cariogenic biofilm.Here,we report an electrospun fibrous membrane that could inhibit the adhesion and biofilm formation of S.mutans.Also,the polystyrene(PS)/polyvinyl pyrrolidone(PVP)electrospun fibrous membrane altered the 3D biofilm architecture and decreased water-insoluble extracellular polysaccharide production.Notably,the anti-adhesion mechanism which laid in Coulomb repulsion between the negatively charged PS/PVP electrospun fibrous membrane and S.mutans was detected by zeta potential.Furthermore,metagenomics sequencing analysis and CCK-8 assay indicated that PS/PVP electrospun fibrous membrane was microbiome-friendly and displayed no influence on the cell viability of human gingival epithelial cells and human oral keratinocytes.Moreover,an in vitro simulation experiment demonstrated that PS/PVP electrospun fibrous membrane could decrease colony-forming unit counts of S.mutans effectively,and PS/PVP electrospun fibrous membrane carrying calcium fluoride displayed better anti-adhesion ability than that of PS/PVP electrospun fibrous membrane alone.Collectively,this research showed that the PS/PVP electrospun fibrous membrane has potential applications in controlling and preventing dental caries.

Surface structure change properties:Auto-soft bionic fibrous membrane in reducing postoperative adhesion

Peritoneal adhesion is the most common adverse effect following abdominal surgery or inflammation.The occurrence in clinical trials has been successfully reduced using barriers.However,the shortcomings of frequently used adhesion barriers,such as rapid degradation rate of gel barrier and inadequate operation ability of solid barrier,cannot be ignored.In this study,a fibrous membrane with an ECM-like structure was prepared.The adhesion properties were reduced significantly by changing the surface structure.The fibrous membrane caused less inflammatory response and much less peripheral adhesion and intestinal obstruction compared to the casting film and the commercial film with smooth surface,though with the same components.Because of the auto-soft bionic structure and similarity in the mechanical modulus of the tissues,the fibrous membrane was more flexible when it adhered to the tissues,showed excellent effectiveness and biocompatibility.In addition to the rat and miniature pig models,a randomized,placebo-controlled,and multicenter clinical pilot study with 150 patients confirmed that because of its flexibility,biodegradability,and similarity to mechanical modulus and structure with tissues involved,the fibrous membrane served as a favorable implant for preventing post-operation adhesion.

Practical operating flexibility of a bifunctional freestanding membrane for efficient anion exchange membrane water electrolysis across all current ranges

This study explores a symmetric configuration approach in anion exchange membrane(AEM)water electrolysis,focusing on overcoming adaptability challenges in dynamic conditions.Here,a rapid and mild synthesis technique for fabricating fibrous membrane-type catalyst electrodes is developed.Our method leverages the contrasting oxidation states between the sulfur-doped NiFe(OH)_(2) shell and the metallic Ni core,as revealed by electron energy loss spectroscopy.Theoretical evaluations confirm that the S–NiFe(OH)_(2) active sites optimize free energy for alkaline water electrolysis intermediates.This technique bypasses traditional energy-intensive processes,achieving superior bifunctional activity beyond current benchmarks.The symmetric AEM water electrolyzer demonstrates a current density of 2 A cm^(-2) at 1.78 V at 60℃ in 1 M KOH electrolyte and also sustains ampere-scale water electrolysis below 2.0 V for 140 h even in ambient conditions.These results highlight the system's operational flexibility and structural stability,marking a significant advance-ment in AEM water electrolysis technology.

Mechanically durable biomimetic fibrous membrane with superhydrophobicity and superoleophilicity for aqueous oil separation

Developing an effective and mechanically durable biomimetic membrane for the separation of highly emulsified aqueous oil is significant but challenging owing to its low water flux and serious membrane fouling.In this work,a biomimetic membrane with superhydrophobicity and superoleophilicity was rationally developed via co-electrospinning of polysulfonamide/polyacrylonitrile(PSA/PAN)emulsion solution,followed by decorating of a-Fe2 O_(3) nanowire onto the membrane surface to create membrane roughness,and grafting of 1 H,1 H,2 H,2 H-perfluorododecyltrichlorosilane(FTCS)to lower membrane surface free energy.Benefiting from the nanowire-wrapped rough membrane structure and the low surface free energy FTCS,the resultant membrane showed superhydrophobicity with a high water contact angle(WCA)of 156°,superoleophilicity with a low oil contact angle(OCA)of 0°,which can separate the highly emulsified aqueous oil with an ultrahigh permeation flux over 7000 L m2 h-1 and high separation efficiency of about 99%.Significantly,the biomimetic membrane also displayed robust stability for long-te rm separation owing to its adva ntage of antifouling property,showing great potential applications in large-scale aqueous oil treatment.

Polymer Electrolytes Based on Electrospun PEO-P(VdF-HFP) Blends for Lithium-Polymer Batteries

1 Results Electrospinning has attracted immense attention recently as a versatile and easy method to prepare polymer membranes that are made up of thin fibers of micron and sub-micron diameters.Such membranes are particularly suitable as host matrices for polymer electrolytes (PEs) since the interlaying of fibers generate large porosity with fully interconnected pore structure facilitating the easy transport of ions.Characterization of PEs based on electrospun membranes of poly(vinylidene fluoride) (PVd...

A flexible and superhydrophobic upconversionluminescence membrane as an ultrasensitive fluorescence sensor for single droplet detection

A Ln^(3+)-doped(Yb^(3+),Tm^(3+)or Yb^(3+),Er^(3+)co-doped)NaYF4 nanoparticle/polystyrene hybrid fibrous membrane(HFM)was fabricated using an electrospinning technique.The HFM shows upconversion luminescence(UCL),flexibility,superhydrophobicity and processability.The UCL membrane can be used as a fluorescence sensor to detect bioinformation from a single water droplet(~10μl).Based on the fluorescence resonance energy transfer,the detection limits of this sensor can reach 1 and 10 ppb for the biomolecule,avidin,and the dye molecule,Rhodamine B,respectively,which are superior to most of the fluorescence sensors reported in previous works.After the fluorescence detection,the target droplet was easily removed without residues on the UCL membrane surface due to its superhydrophobic property,which exhibits an excellent recyclability that cannot be achieved by traditional liquid-based detection systems.

Surface-functionalized design of blood-contacting biomaterials for preventing coagulation and promoting hemostasis

The anticoagulation and hemostatic properties of blood-contacting materials are opposite lines of research, but their realization mechanisms are inspired by each other. Contact between blood and implantable biomaterials is a classic problem in tribological research, as both antithrombotic and hemostatic materials are closely associated with this problem. Thrombus formation on the surfaces of blood-contacting biomedical devices can detrimentally affect their performance and patient life, so specific surface functionalization is required. Currently, intensive research has focused on the development of super-lubricated or super-hydrophobic coatings, as well as coatings that deliver antithrombotic drugs. In addition, hemostatic biomaterials with porous structures, biochemical substances, and strongly adhesive hydrogels can be used to achieve rapid and effective hemostasis via physical or biochemical mechanisms. This article reviews methods of preparing anticoagulant coatings on material surfaces and the current status of rapid hemostatic materials. It also summarizes fundamental concepts for the design and synthesis of anticoagulant and hemostatic materials by discussing thrombosis and hemostasis mechanisms in biomedical devices and normal organisms. Because there are relatively few reports reviewing the progress in surface-functionalized design for anticoagulation and hemostasis, it is anticipated that this review can provide a useful summary of the applications of both bio-adhesion and bio-lubrication techniques in the field of biomedical engineering.

Fabrication of intra porous PVDF fibers and their applications for heavy metal removal,oil absorption and piezoelectric sensors

Intra porous fibrous membranes have enhanced metal ionic adsorption and oil separation abilities than those of intra nonporous fibrous membrane.In this paper,we prepared highly intra porous fibrous poly(vinylidene fluoride)(PVDF)membranes using an innovated water-mediated electrospinning approach.FTIR-ATR and XRD techniques confirmed the conversion of non-polarα-phase to polarβ-phase in electrospun membranes.The porous fibrous membrane M–16 had adsorbed oil almost 120%and metal adsorption around 15%,12%,5%,13%respectively for Pb^(2+),Cd^(2+),Cu^(2+)and Zn^(2+),which are larger than the counterpart of nonporous M–18.The nonporous fibrous membranes have better peak to peak output voltage(Vp-Vp)2 to 3 times than the porous fibrous membranes(M–16).The results show apparent potential applications in wastewater/oil spill treatment as well as piezoelectric sensors.