Composite chitosan/poly(ethylene oxide) electrospun nanofibrous mats as novel wound dressing matrixes for the controlled release of drugs

The aim of this study was to develop novel biomedical electrospun nanofiber mats for controlled drug release, in particular to release a drug directly to an injury site to accelerate wound healing. Here, nanofibers of chitosan (CS), poly(ethylene oxide) (PEO), and a 90 : 10 composite blend, loaded with a fluoroquinolone antibiotic, such as ciprofloxacin hydrochloride (CipHCl) or moxifloxacin hydrochloride (Moxi), were successfully prepared by an electrospinning technique. The morphology of the electrospun nanofibers was investigated by scanning electron microscopy. The functional groups of the electrospun nanofibers before and after crosslinking were characterized by Fourier transform infrared spectroscopy. X‐ray diffraction results indicated an amorphous distribution of the drug inside the nanofiber blend. In vitro drug‐release evaluations showed that the crosslinking could control the rate and period of drug release in wound‐healing applications. The inhibition of bacterial growth for both Escherichia coli and Staphylococcus aureus were achieved on the CipHCl‐ and Moxi‐loaded nanofibers. In addition, both types of CS/PEO and drug‐containing CS/PEO nanofibers showed excellent cytocompatibility in the cytotoxicity assays. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42060.     

A fundamental study of chitosan/PEO electrospinning

A highly deacetylated (97.5%) chitosan in 50% acetic acid was electrospun at moderate temperatures (25-70 °C) in the presence of a low content of polyethylene oxide (10 wt% PEO) to beadless nanofibers of 60-80 nm in diameter. A systematic quantitative analysis of the solution properties such as surface tension, conductivity, viscosity and acid concentration was conducted in order to shed light on the electrospinnability of this polysaccharide. Rheological properties of chitosan and PEO solutions were studied in order to explain how PEO improves the electrospinnability of chitosan. Positive charges on the chitosan molecule and its chain stiffness were considered as the main limiting factors for electrospinability of neat chitosan as compared to PEO, since surface tension and viscosity of the respective solutions were similar. Various blends of chitosan and PEO solutions with different component ratios were prepared (for 4 wt% total polymer content). A significant positive deviation from the additivity rule in the zero shear viscosity of chitosan/PEO blends was observed and believed to be a proof for strong hydrogen bonding between chitosan and PEO chains, making their blends electrospinnable. The impact of temperature and blend composition on the morphology and diameter of electrospun fibers was also investigated. Electrospinning at moderate temperatures (40-70 °C) helped to obtain beadless nanofibers with higher chitosan content. Additionally, it was found that higher chitosan content in the precursor blends led to thinner nanofibers. Increasing chitosan/PEO ratio from 50/50 to 90/10 led to a diameter reduction from 123 to 63 nm. Producing defect free nanofibrous mats from the electrospinning process and with high chitosan content is particularly promising for antibacterial film packaging and filtration applications.     

Facile preparation and thermal performances of hexadecanol/crosslinked polystyrene core/shell nanocapsules as phase change material

In this study, we report the synthesis of nanoencapsulated phase change material (PCM) with hexadecanol as core and crosslinked polystyrene (PS) as shell material via facile one‐pot emulsion polymerization and its thermal performances. By this method, no high shear homogenization is required to create nanocapsules in emulsion polymerization. The nanosized core/shell structure of the hexadecanol/PS capsules was confirmed by scanning electron microscopy and transmission electron microscope. Thermal performances of the nanoencapsulated PCM were determined using differential scanning calorimetry and thermogravimetry. The results indicated that the hexadecanol/PS nanocapsules had relatively high latent heat of fusion and good thermal stability, which make them attractive for thermal energy storage and heat transfer applications. POLYM. COMPOS., 35:2154–2158, 2014. © 2014 Society of Plastics Engineers     

Preparation of phase change materials microcapsules by using PMMA network‐silica hybrid shell via sol‐gel process

Encapsulation of phase change materials (PCM) using a poly(methyl methacrylate) network‐silica hybrid as the shell material has been developed. n‐Octadecane melted at 28°C was used as PCM. Based on the suspension polymerization process, the microcapsules were prepared successfully by mixing and by the reaction of ethylene glycol dimethacrylate with precopolymer solution with tetraethoxysilane (TEOS), whose resultant microcapsules had higher latent heat (ΔH = 151 J/g) than those without TEOS (ΔH = 88.3 J/g). The average size of the PCM microcapsules was about 10 μm. The silica content, n‐octadecane content, and latent heat of microcapsules were changed with varying ageing conditions, ageing time, and temperature. The highest amount of latent heat (ΔH = 178.9 J/g) and n‐octadecane content (73.3%) of the microcapsule were obtained when the inorganic/organic ratio of the microcapsule was 5%. It was difficult to increase n‐octadecane content (74% to 55.7–67.9%) and latent heat (180.5 J/g to 135.9–165.7 J/g) of the microcapsules by introducing different functional groups of coupling agents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Sea‐island polyurethane/polycarbonate composite nanofiber fabricated through electrospinning

Sea‐island polyurethane (PU)/polycarbonate (PC) composite nanofibers were obtained through electrospinning of partially miscible PU and PC in 3 : 7 (v/v) N,N‐dimethylformamide (DMF) and tetrahydrofuran (THF) mixture solvent. Their structures, mechanical, and thermal properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG), and differential scanning calorimetry (DSC). The structures and morphologies of the nanofibers were influenced by composition ratio in the binary mixtures. The pure PC nanofiber was brittle and easy to break. With increasing the PU content in the PU/PC composite nanofibers, PU component not only facilitated the electrospinning of PC but improved the mechanical properties of PU/PC nanofibrous mats. In a series of nanofibrous mats with varied PU/PC composition ratios, PU/PC 70/30 showed excellent tensile strength of 9.60 Mpa and Young's modulus of 55 Mpa. After selective removal of PC component in PU/PC composite nanofibers by washing with acetone, the residual PU maintained fiber morphology. However, the residual PU nanofiber became irregular and contained elongated indents and ridges along the fiber surface. PU/PC composite fibers showed sea‐island nanofiber structure due to phase separation in the spinning solution and in the course of electrospinning. At PC content below 30%, the PC domains were small and evenly dispersed in the composite nanofibers. As PC content was over 50%, the PC phases became large elongated aggregates dispersed in the composite nanofibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Poly(methyl methacrylate) copolymer nanocapsules containing phase‐change material (n‐dodecanol) prepared via miniemulsion polymerization

Poly(methyl methacrylate) copolymer nanocapsules containing the phase‐change material n‐dodecanol, which could be used for energy storage, were prepared with different comonomers via miniemulsion polymerization. The thermal properties, morphology, and composition of nanocapsules were characterized with differential scanning calorimetry, thermogravimetric analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy. The results show that the thermal properties and morphology of the nanocapsules were influenced greatly by the type and amount of comonomers. Under the same dosage of 4 wt %, the nanocapsules prepared with the comonomer acrylamine and which had a moderate hydrophilicity showed the highest phase‐change latent heat of 109.3 J/g; the acrylamine that had a moderate hydrophilicity and the highest encapsulation efficiency of 91.3%. The size of the nanocapsules ranged from 50 to 100 nm with a uniform spherical shape and apparent core–shell structure. We also found that when the amount of the soft comonomer butyl acrylate was increased, the phase‐change latent heat of the nanocapsules first decreased slightly, then increased to the maximum value with deformed spherical and conglutinated morphology, and finally decreased continuously. The thermal stability of the nanocapsules became weaker with higher contents of core material. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42334.     

Self synthesize of silver nanoparticles in/on polyurethane nanofibers: Nano‐biotechnological approach

In this study, we are introducing a new class of Polyurethane (PU) nanofibers containing silver nanoparticles (NPs) by electrospinning. A simple method not depending on the addition of foreign chemicals has been used to self‐synthesize of silver NPs in/on PU nanofibers. Typically, a sol?gel consisting of AgNO₃/PU/N,N‐dimethylformamide (DMF) has been electrospun and aged for a week, so silver NPs have been created in/on PU nanofibers. Syntheses of silver NPs were carried out by exploiting the reduction ability of the DMF solvent which is the main constituent to obtain PU electrospun nanofibers in decomposition of silver nitrate precursor into silver NPs. Physiochemical characterizations confirmed well oriented nanofibers and good dispersing of pure silver NPs. Various parameters affecting utilizing of the prepared nanofibers on various nano‐biotechnological fields have been studied. For instance, the obtained nanofiber mats were checked for mechanical properties which showed the improvement of the tensile strength upon increase in silver NPs content. Moreover, the nanofibers were subjected to 10 times successive washing experiments with using solid to liquid ratio of 3 : 5000 for 25 h, UV spectroscopy analysis reveals no losses of silver NPs from the PU nanofibers. 3T3‐L1 fibroblasts were cultured in presence of the designed nanofibers. The morphological features of the cells attached on nanofibers were examined by BIO‐SEM, which showed well attachment of cells to fibrous mats. The cytotoxicity results indicated absence of toxic effect on the 3T3‐L1 cells after cell culturing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of filler content on the structure‐property behavior of poly(ethylene oxide) based polyurethaneurea‐silica nanocomposites

Poly(ethylene oxide) (PEO) based polyurethaneurea‐silica nanocomposites were prepared by solution blending and characterized by Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Differential Scanning Calorimetry and tensile testing. The colloidal silica nanoparticles with an average size of 50 nm were synthesized by modified Stöber method in isopropanol. Silica particles were incorporated into three cycloaliphatic polyurethaneurea (PUs) copolymers based on PEO oligomers with molecular weights of 2,000, 4,600, and 8,000 g/mol. Hard segment content of PUs was constant at 30% by weight. Silica content of the PU nanocomposites varied between 1 and 20% by weight. Soft segment (SS) glass transition and melting temperatures slightly increased with increasing filler content for all the copolymers. Degree of SS crystallinity first increased with 1% silica incorporation and subsequently decreased by further silica addition. Elastic modulus and tensile strengths of PU copolymers gradually increased with increasing amount of the silica filler. Elongation at break values gradually decreased in PEO‐2000 based PU copolymer with increasing silica content, whereas no significant change was observed in PUs based on PEO‐4600 and PEO‐8000. Enhancement in tensile properties of the materials was mainly attributed to the homogeneous distribution of silica filler in polymer matrices and strong polymer‐filler interactions. POLYM. ENG. SCI., 58:1097–1107, 2018. © 2017 Society of Plastics Engineers     

Scaffolds based on hydroxypropyl starch: Processing,morphology, characterization,and biological behavior

In this study, a novel electrospun hybrid scaffold was developed, which consists of a blend of a modified natural substance, hydroxypropyl starch (HPS) with a synthetic one, poly(ethylene oxide) (PEO). Nanofibers with varying polysaccharide contents were fabricated using water as solvent and the electrospinning process conditions investigated as a function of the weight ratio of the blend. The fibers were characterized through mean diameter and morphology by scanning electron microscopy. Micrographs clearly showed the effect of HPS/PEO weight ratio of the blend on the nanofibers formation. Stability of the fibers was enhanced by coating with hydrophobic poly(methyl methacrylate) (PMMA). In vitro degradation analysis of the coated mats after 1 month of immersion showed porous formation, whereas the fibrous structure was retained. The biological response of the mats against human fibroblasts proved that cells were able to adhere to and proliferate on the fibrous materials. Thus, the feasibility of producing nanofibers of HPS/PEO blends with high proportion of starch and their biocompatibility after coating with PMMA was demonstrated, indicating that these materials have potential to be used as scaffolds in tissue engineering applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci., 2013     

Multi-Phase Composite Nanofibers via Electrospinning of Latex Containing Nanocapsules with Core-Shell Morphology

Nanocapsules containing hexadecane (HD) as core material and polystyrene (PS) as shell, were electrospun with polyethylene oxide (PEO) as a matrix material into the fiber webs. The morphology and thermal properties of PEO fibers containing (1) both PS nanocapsules with core-shell morphology and solid PS particles, (2) only solid PS particles, and (3) without any PS particles, were compared and the effect of PEO concentration on morphology of the resultant fibers have been studied. The resultant fibers were characterized by means of Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). Both TEM observation and DSC analyses confirmed that the PS nanocapsules were encapsulated within the PEO nanofibers. The fibers had an average diameter of 950 nm for nanocapsules containing parts, 300 nm for solid particles containing parts, and 150 nm for usual parts. The phase change temperatures and phase transition heat of the produced fibers were determined by DSC analyses. TGA was also used to confirm the preparation of multi phase fibers and to determine the amount of HD within the fibers.     

Cocontinuous cellulose acetate/polyurethane composite nanofiber fabricated through electrospinning

Cocontinuous cellulose acetate (CA)/polyurethane (PU) composite nanofibers were obtained through electrospinning of partially miscible CA and PU in 2:1 N,N‐dimethylacetamide (DMAc)/acetone mixture solvent. Their structures, mechanical, and thermal properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The structures and morphologies of the nanofibers were affected by component ratio in the binary mixtures. PU component not only facilitated the electrospinning of CA at CA concentration down to 12 wt%, but reinforced the tensile strength of CA/PU nanofibrous mats, while semirigid component CA in the composite nanofibers could greatly improve the rigidity and dimensional stability of CA/PU nanofibrous mats. In a series of nanofibrous mats with varied CA/PU composition ratios, CA/PU 20/80 showed excellent tensile strength and Young's modulus. The residual product after selective removal of any one of the components in CA/PU composite nanofibers by washing with proper solvent maintained the fiber structure but greatly reduced the fiber size, suggesting CA/PU composite fibers showed a cocontinuous nanofiber structure due to phase separation in the spinning solution and in the course of electrospinning. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Study on microstructure and mechanical properties of polydiacetylene composite biosensors

10,12-Pentacosadiynoic acid (PCDA) monomers were mixed with polyurethane (PU) or poly(ethylene oxide) (PEO) and the mixtures were electrospun to obtain composite nanofibers that were then photopolymerized via ultraviolet radiation, resulting polydiacetylene (PDA) in the nanofibers. The PDA demonstrated color-changing properties in the presence of Escherichia coli, which exhibited potential for developing flexible colorimetric biosensors for medical textiles. Phase separation was found in the PEO–PDA fibers, resulting in amorphous PEO accumulation at the fiber surface. In contrast, the PU–PDA fibers demonstrated a homogeneous microstructure throughout the fibers. Tensile test results suggested a molecular orientation in the PU–PDA fibers that significantly improved the mechanical properties of the fibers. The presence of PDA in the matrix polymer reduced the overall strength and breaking elongation of both composite nanofibers in comparison to 100% PEO and PU fibers. A single PU–PDA fiber showed significantly higher stiffness and modulus than a single PEO–PDA fiber. Force–distance curve analysis suggested that the PU–PDA fibers exhibited an elastic deformation. In a comparison, the PEO–PDA fibers were brittle and showed low modulus. The results of structural and mechanical properties suggest that the PU–PDA nanofibers are a promising composite for developing nonadherent, durable, and flexible colorimetric biosensors used in medical textiles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47877.     

The morphology and mechanical properties of sodium alginate based electrospun poly(ethylene oxide) nanofibers

The electrospinning of sodium alginate, a natural biopolymer, was performed from aqueous solutions by blending with PEO, a biodegradable polymer. The conductivity and surface tension of solutions of sodium alginate and PEO were investigated by standard methods. The morphology, thermal, and mechanical properties of the electrospun nanofibers were studied using field emission scanning electron microscopy (FE‐SEM), fourier transform infrared spectroscopy (FT‐IR), energy dispersive X‐ray (EDX), differential scanning calorimetry (DSC) and tensile testing. Uniform, smooth, and ultra‐fine nanofibers with diameters of ～140–190 nm were obtained with solution concentrations of 6–7.2% and sodium alginate/PEO volume ratios of 30:70–50:50. The mechanical strength of the electrospun sodium alginate/PEO mats with good morphology was 21 MPa compared to PEO mats which had a strength of only 10 MPa. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Preparation and characterization of nano-encapsulated n-tetradecane as phase change material for thermal energy storage

Nanocapsules used as phase change material (PCM) were prepared by using in situ polymerization methods. N-Tetradecane was used as the core material. Urea and formaldehyde were used for the shell polymerization. Sodium dodecyl sulfate was used as the emulsifier and resorcin was used as the system modifier. The morphology of the nanocapsules was observed by a scanning electronic microscope (SEM). The thermal properties were investigated by a differential scanning calorimeter (DSC) and a thermogravimetry analysis (TGA). The SEM analysis indicated that the nanocapsules had general size of about 100 nm and the core material was well encapsulated. DSC analysis indicated that the mass content of n-tetradecane was up to 60%, which resulted in a high latent heat of fusion of 134.16 kJ/kg. TGA showed the thermal stability of the nanocapsules could be improved by the additives (NaCl) used in the polymerization. The nanocapsules could be applied for thermal energy storage and heat transfer enhancement.     

Effects of hard and soft components on the structure formation,crystallization behavior and mechanical properties of electrospun poly(l-lactic acid) nanofibers

The effects of multi-wall carbon nanotubes (MWCNTs) and poly(ethylene oxide) (PEO) on the structure formation, morphology, crystallization behavior and mechanical property of electrospun poly (l-lactic acid) (PLLA) nanofiber mats were investigated by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC) and mechanical test. If incorporate hard filler, MWCNTs into electrospun PLLA nanofiber, the crystallinity, chain orientation, and crystallization behaviors were almost not influenced by the MWCNTs content owing to the MWCNTs mainly acted as impeding the crystal growth and chain diffusion. If incorporate small content of soft and miscible component, PEO (10 wt%) into the electrospun PLLA and PLLA/MWCNTs nanofibers, the crystallinity and crystallization rate of PLLA in nanofibers were obviously enhanced. The synergistic effect of PEO and MWCNTs in PLLA nanofibers was observed during melt-crystallization behaviors of PLLA/MWCNTs fibers. Based on those results, we found that the chain mobility is an important factor to influence the structure formation and crystallization behaviors in the electrospun nanofibers. Our results indicated that the structure and properties of electrospun nanofibers could be optimized by compounding with hard inorganic filler and soft polymer components.     

Electrospinning of waterborne polyurethanes

Polyurethane (PU) fibers were obtained by electrospinning of waterborne PU dispersions. As dispersion cannot be electrospun, a water‐soluble polymer (poly (ethylene oxide) (PEO)) was dissolved in the PU dispersion and fibers were obtained from electrospinning the resulting mixture. Pure PU fibers were obtained after removing PEO with water extraction. Continuous PU fibers were obtained using a PU/PEO weight ratio higher than 2.5. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Electrospinning of high‐molecule PEO solution

Electrospinning is a simple but powerful method for making nanofibers that can then be collected to create porous mats. We expand the range of this technique by making nanofibers from macromolecules with a molecular weight of 3,000,000, namely poly(ethylene oxide) (PEO). Gelation of PEO blocks its spinning by traditional electrospinning. PEO was mixed with pure alcohol, and in specific concentration 10 wt % and under vibration condition, the mixed solution behaves like polymers for electrospinning, the average diameter of the obtained nanofibers is about 100 nm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3840–3843, 2007     

Electrospinning of cellulose‐based nanofibers

Cellulose derivatives of carboxymethyl cellulose sodium salt (CMC), hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), and enzymatically treated cellulose have been electrospun, and the microstructure of the resulting nanofibers has been analyzed by scanning electron microscopy (SEM). Before electrospinning, the solutions were characterized by viscometry and surface tension measurements, and the results were correlated with spinnability. Four different CMC derivatives, varying in molecular weight (M_w), degree of substitution (DS), and substitution pattern, have been electrospun in mixtures with poly(ethylene oxide) (PEO), and nanofibers of various characteristics have formed. The CMC‐based nanostructures, i.e., the nonwoven sheet and individual nanofibers, proved to be independent of M_w and DS but largely dependent on the substitution pattern. The nonwoven sheets varied in homogeneity, and beads appeared on the individual fibers. Depending on the chemical nature of the CMC, the extraction of PEO resulted in pure CMC nanostructures of varying appearance, indicating that the distribution of PEO and CMC in the nanofibers also varied. Two different HPMC derivatives, varying in DS, were electrospun into nanofibers. Homogeneous nonwoven sheets based on nanofibers of similar appearance are formed, independent of the substitution content of the HPMC sample. Preliminary fibers were obtained from enzymatically treated cellulose in a solvent system based on lithium chloride dissolved in dimethyl acetamide (LiCl: DMAc). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1473–1482, 2007     

Vergleich dreier Latentwärmespeicherkonzepte zur effizienten Nutzung von Niedertemperaturwärme

In order to store thermal energy at a low temperature, three types of latent heat storage systems are presented and compared. The storage systems are a direct contact latent heat storage system, a latent heat system with an encapsulated phase change material (PCM) and a water reservoir with a PCM jacket. These heat systems are utilized for an efficient use of renewable energies and low‐temperature waste heat. The storage medium is a salt hydrate with a melting point of 27 °C. This work presents the three concepts including corresponding applications and a discussion of the experimental results.     

Chain conformation,crystallization behavior,electrical and mechanical properties of electrospun polymer-carbon nanotube hybrid nanofibers with different orientations

An improved electrospinning technique was used to produce poly(ethylene oxide) (PEO) and PEO-multi-walled carbon nanotube (MWCNT) hybrid nanofibers. By this technique, both the orientation of MWCNTs in the electrospun PEO nanofibers and the orientation of electrospun PEO–MWCNT hybrid nanofibers can be controlled. The morphologies of the as-spun PEO–MWCNT hybrid nanofibers and the dispersion and orientation of MWCNTs in the fiber matrix were observed by scanning and transmission electron microscopy. The effect of electrospinning process and the incorporation of MWCNTs on the chain conformation and semicrystalline framework of PEO were examined by Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, and differential scanning calorimetry, and compared with pure PEO and PEO–MWCNT films prepared by casting. Finally, to investigate how the fiber assemblies affect the mechanical and electrical properties of the hybrid materials, tensile testing and impedance analysis were performed on randomly oriented, uniaxially and biaxially oriented PEO–MWCNT hybrid nanofiber mats. The results indicated that both the uniaxially and biaxially oriented assembled hybrid materials have better tensile strength, modulus, and electrical conductivity compared with random nanofibers.