Freestanding fiber mats of zeolitic imidazolate framework 7 via one‐step,scalable electrospinning

We demonstrated the fabrication of freestanding zeolitic imidazolate framework 7 (ZIF‐7) nanofiber (NF) mats by means of one‐step, scalable electrospinning. The formation of ZIF‐7 nanoparticles embedded in polymer fibers was unambiguously pinpointed via X‐ray diffraction, transmission electron microscopy, and adsorption studies. The NF mats exhibited excellent characteristics, with an average diameter of 245 nm, in the adsorption and desorption of carbon dioxide (CO₂); this makes them attractive candidates for gas separation and other selective filtration applications. This excellent property of the ZIF‐7 mats was explained by the gate‐opening phenomenon of ZIF‐7, which yielded a stepwise increase in the overall CO₂ uptake capacity. The mechanical strength of the NF mats was also obtained via large‐strain uniaxial tensile deformation, which enabled preliminary assessment of the mat's suitability for textiles and membranes in targeting separation and filtration applications with large‐area permeability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43788.     

Drug‐loaded polyurethane/clay nanocomposite nanofibers for topical drug‐delivery application

In this study, polyurethane/nanoclay nanocomposite nanofibrous webs were prepared by electrospinning. An antiseptic drug, chlorhexidine acetate (CA), was loaded onto montmorillonite clay and was then incorporated into polyurethane nanofibers. For comparison, the CA drug was loaded directly into the polyurethane solution dope used to electrospin the nanofibers. The emphasis was on investigating the effect of the drug loading into the nanoclay vis‐à‐vis direct drug loading on the drug‐release behavior of nanofibrous webs. The nanofibrous webs were also evaluated for other properties, such as moisture vapor transmission, porosity determination, contact angle measurement, and antibacterial activity, which are important for topical drug‐delivery application. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40230.     

Fabrication and properties of core‐shell structure P(LLA‐CL) nanofibers by coaxial electrospinning

In this article, core‐shell structure nanofibers were fabricated by coaxial electrospinning with biodegradable copolymer Poly(L ‐Lactic‐ε‐Caprolactone) [P(LLA‐CL) 50 : 50] as shell and bovine serum albumin (BSA) as core. Morphology and microstructure of the nanofibers were characterized by scanning electron microscopy and transmission electron microscopy. The mechanical properties were investigated by stress‐strain tests. In vitro degradation rates of the nanofibrous membranes were determined by measuring their weight loss when immersed in phosphate‐buffered saline (pH 7.4) for a maximum of 14 days. Release behavior of BSA was measured by an ultraviolet‐visible spectroscopy, and the results demonstrated that BSA could release from P(LLA‐CL) nanofibers in a steady manner. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of ibuprofen‐loaded HDPE tubular devices for application as urinary catheters

In this study, high‐density polyethylene tubes with the incorporation of ibuprofen (IBP) were investigated with a view to their application as urinary catheters. The melt extrusion process was used to prepare the urinary catheters, and the influence of the manufacturing parameters on the material properties was evaluated. Samples prepared at lower temperature resulted in a more homogeneous material with a smoother surface, lower crystallinity, and better mechanical properties. The drug release was faster in the first 4 days, due to the accumulation of the drug on the outer surface of tubes. The concentration of IBP released was similar to the drug content in commercially available topic formulations (5%). Furthermore, after 2 days of immersion, the release achieved the concentration known to inhibit bacterial growth (6 mg/mL). These characteristics indicate that this material has good potential for application in urinary catheters. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45661.     

Controlled release of protein from core–shell nanofibers prepared by emulsion electrospinning based on green chemical

Direct application of active protein in practical food system suffers from the major disadvantage of protein inactivation caused by food components and environmental factors. This study is the first to encapsulate water‐soluble protein into hydrophobic polystyrene (PS) polymer via emulsion electrospinning technique based on green chemical L‐limonene to achieve sustained release of protein. Core–shell nanostructure with elongated domains was observed in electrospun fibers. In vitro release profiles suggest that a sustained release of protein was achieved. The increased release rate with PS molecular weight reveals that the release of protein could be well tuned by tailoring polymeric molecular weight, which is possibly attributed to the association of release rate with fiber inner structure and protein distribution in matrix. These results demonstrate that an excellent protein delivery system could be obtained via emulsion electrospinning based on green chemical for the application in antimicrobial packaging and filtration in food industry. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41811.     

A Comparison of Electric‐Field‐Driven and Pressure‐Driven Fiber Generation Methods for Drug Delivery

Polymeric fibers are prepared by using electric field driven fiber production technology—electrospinning and pressure driven fiber production technology—pressurized gyration. Fibers of four different polymers: polyvinylidene fluoride (PVDF), poly(methyl methacrylate (PMMA), poly(N‐isopropylacrylamide), and polyvinylpyridine (PVP), are spun by both techniques and differences are analyzed for their suitability as drug carriers. The diameters of electrospun fibers are larger in some cases (PVDF and PMMA), producing fibers with lower surface area. Pressurized gyration allows for a higher rate of fiber production. Additionally, drug‐loaded PVP fibers are prepared by using two poorly water‐soluble drugs (Amphotericin B and Itraconazole). In vitro dissolution studies show differences in release rate between the two types of fibers. Drug‐loaded gyrospun fibers release the drugs faster within 15 min compared to the drug‐loaded electrospun fibers. The findings suggest pressurized gyration is a promising and scalable approach to rapid fiber production for drug delivery when compared to electrospinning.     

Synthesis of N‐benzyl‐O‐carboxymethylchitosan and application in the solubilization enhancement of a poorly water‐soluble drug (triamcinolone)

N‐Benzyl‐O‐carboxymethyl chitosan (OCChB) was synthesized through a reaction of O‐carboxymethylchitosan (OCCh) and benzaldehyde by the reductive amination method. The chemical structures and physical properties of the derivatives were confirmed by Fourier transform infrared spectroscopy and ¹H‐NMR. The cytotoxicity of the polymers was tested by MTT (3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐diphenyltetrazolium bromide) assay at concentrations ranging from 0.01 to 1000 μg/mL. The substitution degrees of the derivatives, calculated by ¹H‐NMR, were 12 and 53% for OCChB1 and OCChB2, respectively. The results show that the derivatives were not toxic at 1000 μg/mL and could decrease the surface tension by concentration on the system surface compared with OCCh. Because of this property, OCChB was applied as a solubility enhancer for triamcinolone (TC), a poorly water‐soluble drug. The polymer solutions at 1.0 mg/mL increased the TC solubility up to 3.5 times for OCChB1 and 5.0 times for OCChB2 compared with its solubility in water. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation,characterization, antibacterial properties,and hemostatic evaluation of ibuprofen‐loaded chitosan/gelatin composite films

Ibuprofen‐loaded chitosan/gelatin (CS/GE) composite films were fabricated in this work. The morphology of the composite film was investigated using scanning electron microscopy. The functional groups of the composite film before and after crosslinking were characterized using Fourier transform infrared spectroscopy. Meanwhile, the mechanical properties, antibacterial performance, cytocompatibility, and hemostatic activity of the composite films were investigated. The results show that the amount of CS affected the mechanical properties and liquid uptake capacities of the composite films. The composite film showed better bactericidal activity against Staphylococcus aureus than Escherichia coli. In vitro drug‐release evaluations showed that crosslinking could control the drug‐release rate and period in wound healing. Both types of CS/GE and drug‐loaded CS/GE composite films also showed excellent cytocompatibility in cytotoxicity assays. The hemostatic evaluation indicated that the composite film crosslinked by glutaraldehyde in rabbit livers had a dramatic hemostatic efficacy. Therefore, ibuprofen‐loaded CS/GE composite films are potentially applicable as a wound dressing material. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45441.     

Fabrication of superhydrophobic fiber coatings by DC‐biased AC‐electrospinning

Mesh‐like fiber mats of polystyrene (PS) were deposited using DC‐biased AC‐electrospinning. Superhydrophobic surfaces with water contact angles greater than 150° and gas fraction values of up to 97% were obtained. Rheological study was conducted on these fiber surfaces and showed a decrease in shear stress when compared with a noncoated surface (no slip), making them excellent candidates for applications requiring the reduction of skin‐friction drag in submerged surfaces. We have also shown that addition of a second, low‐surface energy polymer to a solution of PS can be used to control the fiber internal porosity depending on the concentration of the second polymer. Contact‐angle measurements on mats consisting of porous and nonporous fibers have been used to evaluate the role of the larger spaces between the fibers and the pores on individual fibers on superhydrophobicity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Emulsion‐electrospinning n‐octadecane/silk composite fiber as environmental‐friendly form‐stable phase change materials

The ultrafine n‐octadecane/silk composite fibers as form‐stable phase change materials were successfully developed by the emulsion‐electrospinning method. The effect of n‐octadecane content in the emulsion on the morphology and thermal energy storage capacity of the composite fibers were scientifically investigated. Scanning electron microscopy images show that the composite fibers display cylindrical shape with smooth surface and uniform diameter. Differential scanning calorimetry results demonstrate that the composite fibers exhibit reversible phase transition behavior, high thermal energy storage capacity, and good thermal reliability. Meanwhile, the composite fibers exhibit the capability to regulate their interior temperature as the ambient temperature alters according to the thermo‐infrared images. In addition, the composite fibers are friendly to the environment due to the biodegradability of silk. Therefore, the n‐octadecane /silk composite fibers have the great potential application of serving as form‐stable phase change materials for thermal energy storage and thermal regulation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45538.     

Multifunctional ternary drug‐loaded electrospun scaffolds

Multifunctional electrospun scaffolds were prepared from two polylactide (PLA) grades having slightly different d ‐lactide content (4.2 wt % and 2.0 wt %). Triclosan (TCS), ketoprofen (KTP), and p‐coumaric acid (CUM) were selected as bactericide, anti‐inflammatory, and antioxidant agents, respectively. Single, binary, and ternary drug‐loaded microfibers having a unimodal diameter distribution could be prepared using a common chloroform:acetone:dimethylsulfoxide mixture and similar operational parameters (i.e., voltage, flow rate, and tip–collector distance). FTIR spectra were sensitive to the low amount of drugs loaded and even showed slight differences in PLA conformation. DSC heating scans clearly demonstrated the ability of electrospinning to induce molecular orientation of PLA and also the nucleation effect of incorporated drugs to induce crystallization. Thus, crystallinity of binary drug‐loaded scaffolds was significantly higher than observed for unloaded samples. Release behavior of the three drugs from loaded scaffolds and PLA matrices in PBS:ethanol medium was evaluated. A rapid release was always detected, together with partial drug retention which was higher when the more stereoregular PLA matrix was employed. A strong bactericidal effect was found when scaffolds were loaded with 3 wt/vol % of TCS, but incorporation of a small percentage of KTP (i.e., 1 wt/vol %) had a bacteriostatic effect even in the absence of TCS. The inherent cytotoxicity of TCS could be well neutralized by enhancing cell viability by incorporation of CUM and/or KTP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42751.     

One‐step facile process to obtain insoluble polysaccharides fibrous mats from electrospinning of water‐soluble PMDA/cyclodextrin polymer

Herein, we used an electrospinning process to develop nanofibers based on poly‐cyclodextrin. This article describes a simple and effective method to produce fibers of a water‐soluble hyperbranched polymer based on β‐CD and pyromellitic dianhydride via electrospinning. The obtained fibers were made insoluble in water with a simple thermal crosslinking without the use of further reactive or solvent. After 24 h of dipping in distilled water or phosphate buffer solution morphology and size of fibers remain unaltered as observed in scanning electron microscopy. The crosslinking mechanism was studied with thermogravimetric analysis, attenuated total reflectance–Fourier infrared spectroscopy, and elemental analysis and a reaction mechanism is proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46490.     

Ultrafine cellulose triacetate mats electrospun by using co‐solvent of DMSO/chloroform system

Cellulose triacetate (CTA) nanofiber nonwoven mats were continuously electrospun by using mixed solvent of DMSO/chloroform system. The size and morphology of CTA nanofibers were investigated. It was found that CTA fibers with diameters in the range of 98 nm–1.81 μm were obtained from 8 wt % CTA solutions in 1 : 1, 3 : 2, 2 : 1, 3 : 1, 5 : 1 and 7 : 1 (v/v) DMSO/chloroform. The average diameter of CTA nanofiber was decreased and size distribution was narrowed with increasing the DMSO content in the mixed solvent. Smooth and uniform nanofibers with mean diameters of about 260 nm could be obtained from a solution of CTA in the binary system DMSO/chloroform 5 : 1(v/v) at a polymer concentration of 8 wt %. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40373.     

Irbesartan‐loaded electrospun nanofibers‐based PVP K90 for the drug dissolution improvement: Fabrication,in vitro performance assessment,and in vivo evaluation

Irbesartan with a low bioavailability is known as a poorly water‐soluble drug. The purpose of this investigation is the improvement of physicochemical properties (such as solubility and dissolution rate) of Irbesartan using electrospun nanofibers‐based solid dispersion preparation. Nanofibers were prepared using certain weight ratios of the drug and polyvinylpyrrolidone K90 (PVP K90). Then, dissolution studies were carried out. Moreover, selected samples were examined by many different tests such as Fourier transform infra red (FTIR), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), high‐performance liquid chromatography (HPLC), and scanning electron microscopy (SEM). Though solubility and dissolution rate of all Irbesartan‐PVP nanofibers improved, but the best result was obtained through of ENSD5 (3% (w/v) : 7% (w/v)). In sink condition approximately 97% of this sample was released during 60 min. The drug content was among the different batches from 40.55 ± 1.01 to 245.32 ± 1.77 μg/mL. The maximum saturation solubility was belonged to this sample. According to the results of the thermal analysis and FTIR spectroscopy, there is no chemical reaction between drug and carrier, also samples has not changed during the process. Amorphous structure for nanofibers was confirmed by DSC thermograms and XRD diffractograms and morphological structure of samples were observed by SEM images. Ultimately, in vivo studies were performed in healthy grey rabbits and the results were satisfactory. The drug–polymer nanofibers showed an increase in relative bioavailability than the plain Irbesartan suspension. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42212.     

Preparation and release study of ibuprofen‐loaded porous matrices of a biodegradable poly(ester amide) derived from L‐alanine units

Scaffolds of a biodegradable poly(ester amide) constituted of L ‐alanine, sebacic acid, and 1,12‐dodecanediol units (abbreviated as PADAS) were prepared by the compression‐molding/particulate‐leaching method. The influence of the type, size, and percentage of salt on the scaffold porosity and morphology was evaluated. The thermal behavior and crystallinity were also studied for samples obtained under different processing conditions. PADAS scaffolds were not cytotoxic because they showed good cell viability and supported cell growth at a similar ratio to that observed for the biocompatible materials used as a reference. The use of PADAS scaffolds as a drug‐delivery system was also evaluated by the employment of ibuprofen, a drug with well known anti‐inflammatory effects. Different drug‐loading methods were considered, and their influence on the release in a Sörensen's medium was evaluated as well as the influence of the scaffold morphology. A sustained release of ibuprofen could be attained without the production of a negative effect on the cell viability. The release kinetics of samples loaded before melt processing was well described by the combined Higuchi/first‐order model. This allowed the estimation of the diffusion coefficients, which ranged between 3 × 10^?14 and 5 × 10^?13 m²/s. Samples loaded by immersion in ibuprofen solutions showed a rapid release that could be delayed by the addition of polycaprolactone to the immersion medium (i.e., the release rate decreased from 0.027 to 0.015 h^?1). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Binding of chlorpheniramine maleate to pharmacologically important alginic acid,carboxymethylcellulose, κ‐carageenan,and ι‐carrageenan as studied by diafiltration

The binding of cationic chlorpheniramine maleate (CPM) to the anionic water‐soluble polymers (WSPs) alginic acid, carboxymethylcellulose, κ‐carageenan, and ι‐carageenan was evaluated by diafiltration at pH 7.5 and in the absence and presence of 0.13M NaCl. CPM interacted with all of the WSPs when no NaCl was present in the solution, with charge‐related formation constants of around 700 M^?1 for all of the polymers, whereas the interactions were cleaved in the presence of 0.13M NaCl, indicating interactions of an electrostatic nature screened by the single electrolyte. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 598–602, 2005     

N‐(2‐hydroxypropyl)methacrylamide‐based polymer conjugates with pH‐controlled activation of doxorubicin. I. New synthesis,physicochemical characterization and preliminary biological evaluation

New method of synthesis of water‐soluble polymer‐drug conjugates, exhibiting remarkable anticancer activity in mice models, has been developed. In the conjugates, an anticancer drug doxorubicin (DOX) is attached to a polymer carrier based on N‐(2‐hydroxypropyl)methacrylamide (HPMA) copolymer via a hydrolytically labile hydrazone bond. New methacrylamide‐type comonomers, containing either hydrazide group or hydrazon of DOX, were used for copolymerization with HPMA. In contrast to the synthetic procedure described earlier the new method is simpler, cheaper, and results in a better‐defined conjugate structure. The conjugates are fairly stable in buffer at pH 7.4 (model of blood stream) but release DOX under mild acid conditions modeling the tumor microenvironment. The conjugates showed significant in vivo antitumor activity in treatment of T‐cell lymphoma EL‐4 bearing mice with up to 100% long‐term survivors. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Fabrication and characterization of food‐grade fibers from mixtures of maltodextrin and whey protein isolate using needleless electrospinning

Food‐grade fibers were fabricated from dispersions of maltodextrin and whey protein isolate (WPI) using needleless electrospinning. Two maltodextrins (DE 2) from different starch sources were used and the maltodextrin/WPI ratio was varied. Molecular weight, intrinsic viscosity, entanglement concentration, shear stability, and electrical conductivity were studied as function of maltodextrin type and mixing ratio and correlated to fiber production rate and morphology. The results show that a high molecular weight of the maltodextrin was beneficial to its spinnability. Waxy potato starch maltodextrin (P‐MD) (M_w = 129.6 kDa) and WPI produced fibers with diameters between 1.40 and 1.67 µm at production rates up to 1.65 g/h; while the dispersions with waxy maize starch maltodextrin (M‐MD) (M_w = 85.9 kDa) showed poor spinnability and ruptured fibers. P‐MD/WPI dispersions had a higher viscosity and stronger shear thinning behavior attributed to a stronger entangled polymer network which is beneficial to electrospinning. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46328.     

Core–shell PVA/gelatin nanofibrous scaffolds using co‐solvent,aqueous electrospinning: Toward a green approach

Electrospinning (ES) of gelatin often requires cytotoxic organic solvents or acidic environments, which deteriorate cell recognition sites. In this study, aqueous, non‐toxic, co‐solvent ES was performed to obtain core–shell poly(vinyl alcohol) (PVA)/gelatin nanofiber scaffolds. Effects of the core/shell feed rate ratio (FRR) were investigated on a morphological and mechanical basis. PVA:gelatin ratio of 1:4 was the limiting ratio for specific voltage and electrode distance parameters to obtain uniform fibers. Core–shell bead‐free structures were obtained at 8% PVA and gelatin aqueous solutions. A mean diameter of 280 nm was obtained for 1:1 FRR at 15 kV and 15 cm of electrode distance. Crosslinking resulted in slight improvement in tensile strengths and severe decrease in ductility. Fourier transform infrared spectra revealed retention and improvement of stable secondary structures of gelatin after ES. The scaffolds almost degraded more than 60% in 14 days. Based on the results, present scaffolds hold great promise as suitable candidates for biomedical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46582.     

Rapid fabrication of poly(ε‐caprolactone) nanofibers using needleless alternating current electrospinning

Poly(ε‐caprolactone) ( PCL) biopolymer nanofibers and micro‐fibers have been fabricated for the first time at the rates up to 14.0 g per hour using a needleless and collectorless alternating current electrospinning technique. By combining the ac‐voltage, “green” low toxicity glacial acetic acid (AA) as the solvent and sodium acetate (NaAc) as an additive, beadless PCL fibers with diameters tunable from 150 nm to 2000 nm, varying surface morphology and degree of self‐bundling are obtained. In this new approach, the addition of NaAc plays a crucial role in improving the spinnability of PCL solution and fiber morphology. NaAc reveals the concentration‐dependent effect on charge transfer and rheological properties of the PCL/AA precursor, which results in broader ranges of spinnable PCL concentrations and ac‐voltages suitable for rapid manufacturing of PCL‐based fibers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43232.