Preparation of poly(?-caprolactone)-based polyurethane nanofibers containing silver nanoparticles

In this study, poly(?-caprolactone)-based polyurethane (PCL-PU) nanofibers containing Ag nanoparticles for use in antimicrobial nanofilter applications were prepared by electrospinning 8 wt% PCL-PU solutions containing different amounts of AgNO₃ in a mixed solvent consisting of DMF/THF (7/3 w/w). The average diameter of the pure PCL-PU nanofibers was 560 nm and decreased with increasing concentration of AgNO₃. The PCL-PU nanofiber mats electrospun with AgNO₃ exhibited higher tensile strength, tensile modulus, and lower elongation than the pure PCL-PU nanofiber mats. Small Ag nanoparticles were produced by the reduction of Ag⁺ ions in the PCL-PU solutions. The average size and number of the Ag nanoparticles in the PCL-PU nanofibers were considerably increased after being annealed at 100 °C for 24 h. They were all sphere-shaped and evenly distributed in the PCL-PU nanofibers, indicating that the PCL-PU chains stabilized the Ag nanoparticles well.     

Piezoelectric Nanogenerator Based on Electrospun Cellulose Acetate/Nanocellulose Crystal Composite Membranes for Energy Harvesting Application

Nanogenerators, as the typical conversion of mechanical energy to electrical energy devices, have great potential in the application of providing sustainable energy sources for powering miniature devices. In this work, cellulose acetate/cellulose nanocrystal(CA/CNC) composite nanofiber membranes were prepared by electrospinning method and then utilized to manufacture a flexible pressure-driven nanogenerator. The addition of CNC not only increased the content of piezoelectric cellulose I crystallization but also strengthened the mechanical deformation of the nanofiber membranes, which could greatly enhance the piezoelectric performance of CA/CNC composite membranes. The CA/CNC composite nanofiber membrane with 20%(mass fraction) of CNC(CA/CNC-20%) showed optimal piezoelectric conversion performance with the output voltage of 1.2 V under the force of 5 N(frequency of 2 Hz). Furthermore, the output voltage of the CA/CNC-20% nanogenerator device exhibited a linear relationship with applied impact force, indicating the great potential in pressure sensors.     

Electrospinnability study of pea (Pisum sativum) and common bean (Phaseolus vulgaris L.) using the conformational and rheological behavior of their protein isolates

Pea protein isolate (PPI) and bean protein concentrate (BPC) were evaluated as fiber-forming vegetal source materials through electrospinning using various solvents. The effects of hexafluoroisopropanol (HFIP), trifluoroethanol (TFE), trifluoroacetic acid (TFA), formic acid (FA) and water on rheological and conformational properties of the protein solutions were determined. The morphology and molecular organization of the electrospun structures were studied. All PPI and BPC solutions displayed pseudoplastic behavior. Circular dichroism spectroscopy revealed that β-type turns and β-sheets were the dominant protein conformations in water, HFIP, and TFE. After electrospinning, most of the solutions afforded beads. Fiber-like morphologies were only obtained when BPC was dissolved in HFIP. BPC demonstrated better performance in the electrospinning process than PPI. Denaturation of the protein isolates was not sufficient to form fibers, the viscosity of the solution as well as the vapor pressure of the solvents played an important role in defining the morphology.     

Different regimes of the uniaxial elongation of electrically charged viscoelastic jets due to dissipative air drag

We investigate the effects of dissipative air drag on the dynamics of electrified jets in the initial stage of the electrospinning process. The main idea is to use a Brownian noise to model air drag effects on the uniaxial elongation of the jets. The developed numerical model is used to probe the dynamics of electrified polymer jets at different conditions of air drag force, showing that the dynamics of the charged jet is strongly biased by the presence of air drag forces. This study provides prospective beneficial implications for improving forthcoming electrospinning experiments.     

Production and characterization of elastomeric cardiac tissue-like patches for Myocardial Tissue Engineering

Cardiovascular disease remains the leading cause of death. Damaged heart muscle is the etiology of heart failure. Heart failure is the most frequent cause of hospital and emergency room admissions. As a differentiated organ, current therapeutics and techniques can not repair or replace the damaged myocardial tissue. Myocardial tissue engineering is one of the promising treatment modalities for repairing damaged heart tissue in patients with heart failure. In this work, random Polylactic acid (PLA), Polylactic acid/Polyethylene glycol (PLA/PEG) and random and aligned Polylactic acid/Polyethylene glycol/Collagen (PLA/PEG/COL) nanofiber patches were successfully produced by the electrospinning technique. In vitro cytotoxic test (MTT), morphological (SEM), molecular interactions between the components (FT-IR), thermal analysis (DSC), tensile strength and physical analysis were carried out after production. The resulting nanofiber patches exhibited beadless and smooth structures. When the fiber diameters were examined, it was observed that the collagen doped random nanofiber patches had the lowest fiber diameter value (755 nm). Mechanical characterization results showed that aligned nanofiber patches had maximum tensile strength (5.90 MPa) values compared to PLA, PLA/PEG, and PLA/PEG/COL (random). In vitro degradation test reported that aligned patch had the highest degradation ratio. The produced patches displayed good alignment with tissue on cardiomyocyte cell morphology studies. In conclusion, newly produced patches have noticeable potential as a tissue-like cardiac patch for regeneration efforts after myocardial infarction.     

Degradation patterns and surface wettability of electrospun fibrous mats

Degradation profiles and surface wettability are critical for optimal application of electrospun fibrous mats as drug carriers, tissue growth scaffolds and wound dressing materials. The effect of surface morphologies and chemical groups on surface wettability, and the resulting matrix degradation profiles were firstly assessed for electrospun poly(d,l-lactide) (PDLLA) and poly(d,l-lactide)-poly(ethylene glycol) (PELA) fibers. The air entrapment between the fiber interfaces clarified the effects of various surface morphologies on the surface wettability. Chemical groups with lower binding energy were enriched on the fiber surface due to the high voltage of the electrospinning process, and a surface erosion pattern was detected in the degradation of electrospun PDLLA fibers, which was quite different from the bulk degradation pattern for other forms of PDLLA. Contributed by the hydrophilic poly(ethylene glycol) segments, the degradation of electrospun PELA fibers with hydrophobic surface followed a pattern different from surface erosion and typical bulk degradation.     

Parameter study of electrospinning of polyamide-6

Importance of different solution and process parameters were evaluated in multi-nozzle electrospinning of polyamide-6. We were interested in how those parameters affect firstly on fibre diameters and fibre diameter distribution and secondly on production rate and disturbances of the process. The trial series was planned using orthogonal experimental design. Altogether eight parameters having three or two levels each were chosen for this study. The chosen solution parameters were polymer grade, viscosity of solution, salt content and solvent grade and process parameters, voltage, distance, nozzle size and feeding pressure of solution. This study was performed using continuous electrospinning equipment consisting of multiple nozzles and horizontal electric field. Literature findings about the influences of certain variables are often contradictory. These contradictions and their possible causes were discussed.     

In vitro biocompatibility of electrospun hexanoyl chitosan fibrous scaffolds towards human keratinocytes and fibroblasts

With the ability to form a submicron-sized fibrous structure with interconnected pores mimicking the extracellular matrix (ECM) for tissue formation, electrospinning was used to fabricate ultra-fine fiber mats of hexanoyl chitosan (H-chitosan) for potential use as skin tissue scaffolds. In the present communication, the in vitro biocompatibility of the electrospun fiber mats was evaluated. Indirect cytotoxicity evaluation of the fiber mats with mouse fibroblasts (L929) revealed that the materials were non-toxic and did not release substances harmful to living cells. The potential for use of the fiber mats as skin tissue scaffolds was further assessed in terms of the attachment and the proliferation of human keratinocytes (HaCaT) and human foreskin fibroblasts (HFF) that were seeded or cultured on the scaffolds at different times. The results showed that the electrospun fibrous scaffolds could support the attachment and the proliferation of both types of cells, especially for HaCaT. In addition, the cells cultured on the fibrous scaffolds exhibited normal cell shapes and integrated well with surrounding fibers. The obtained results confirmed the potential for use of the electrospun H-chitosan fiber mats as scaffolds for skin tissue engineering.     

AOPAN/PA-66复合纳米纤维膜的制备及对金属离子的吸附性能

采用双喷头电纺丝技术,将尼龙(PA-66)纤维增强的聚丙烯腈(PAN)纳米纤维膜(PAN/PA-66)与盐酸羟胺进行偕胺肟化反应,制备了一种偕胺肟化聚丙烯腈/尼龙复合纳米纤维膜(AOPAN/PA-66).通过红外光谱及扫描电子显微镜等方法研究了偕胺肟化前后纳米纤维膜的组成、形貌和力学性能;并考察了AOPAN/PA-66复合纳米纤维膜对铜离子和铅离子的吸附性能.结果表明,AOPAN/PA-66复合纳米纤维膜的抗拉伸强度及断裂伸长率分别为4.73 MPa和30.76%,对Cu(Ⅱ)及Pb(Ⅱ)的吸附量分别为67.5和75.4 mg/g.     

导电玻璃负载CuO/V_2O_5复合纳米纤维光电极的制备及光电催化性能

以聚乙烯吡咯烷酮(PVP)为高分子模板剂,乙酰丙酮钒(C_(15)H_(21)O_6V)和三水合硝酸铜[Cu(NO_3)_2·3H_2O]为原料,导电玻璃(FTO)为载体,结合溶胶-凝胶法和静电纺丝技术制备了前驱体纤维,经高温焙烧后得到分布均匀、具有纤维结构的导电玻璃负载的CuO/V_2O_5复合光电极(CuO/V_2O_5/FTO).采用热重-差热分析仪(TG-DTA)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线光电子能谱仪(XPS)等对材料的结构进行表征,以亚甲基蓝(MB)为目标降解物,探讨了合成产物的光电催化性能.结果表明,CuO与V_2O_5能有效形成异质结构,其光电催化活性均比纯V_2O_5有明显提高,并且改变CuO与V_2O_5的比例对光电催化性能有较大影响,其中n(Cu)∶n(V)=1∶1时降解效率最高,达到96%.