Antibacterial ciprofloxacin HCl incorporated polyurethane composite nanofibers via electrospinning for biomedical applications

We report on the preparation and characterization of polyurethane (PU) composite nanofibers by electrospinning. Two different approaches were adopted to obtain the PU composite nanofibers. In the first approach, a homogeneous solution of 10 wt% PU containing ciprofloxacin HCl (CipHCl) drug was electrospun to obtain PU/Drug composite nanofibers. And in the second approach, the PU with ciprofloxacin HCl drug and ceramic hydroxyapatite (HA) particles were electrospun to obtain the PU/Drug and PU/Drug/HA composite nanofibers. The surface morphology, structure, bonding configuration, optical and thermal properties of the resultant products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and UV–vis spectroscopy. The antibacterial activity was tested against common food borne pathogenic bacteria, namely, Staphylococcus aureus, Escherichia coli by the minimum inhibitory concentration (MIC) method. Our result results demonstrate that these composite nanofibers possess superior characteristics which can utilized for variety of applications.     

原位热溶剂法制备ZnO纳米晶/PU复合纳米纤维及其吸附性能研究

通过静电纺丝法制备了直径为(320±51)nm的前驱体醋酸锌/聚氨酯(Zn(OAc)2/PU)复合纳米纤维。将前驱体先后经过0.1 mol/L NaOH乙醇溶液和甘油浴热处理,得到ZnO纳米晶/PU复合纳米纤维。讨论了甘油浴温度和时间对纳米纤维结构和形貌的影响,研究了其吸附性能。实验结果表明,经过0.1 mol/L NaOH乙醇溶液处理后,前驱体纤维Zn(OAc)2/PU转变为ZnO/PU纤维且ZnO主要以低结晶和无定型态存在;再经过甘油浴处理后,低结晶和无定型态的ZnO转变为晶型完整的六方晶系纤锌矿结构,得到了ZnO纳米晶/PU复合纳米纤维,该纤维对有机染料分子罗丹明B有良好的吸附性能。     

Electrospun salicylic acid/polyurethane composite nanofibers for biomedical applications

Salicylic acid (SA)/polyurethane (PU) composite nanofiber mats were fabricated by introducing SA in PU solution during the electrospinning process. Cell viability assays showed that the as-prepared composite nanofibers had a good biocompatibility. Further, the composite mats showed good antibacterial performance against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Easy fabrication, good mechanical properties, good biocompatibility as well as the antibacterial activity of PU nanofibers containing SA indicated their significant promise for a variety of potential medical applications such as tissue engineering, wound healing, and drug delivery system.     

Antimicrobial activity of electrospun polyurethane nanofibers containing composite materials

We report on the preparation and characterization of electrospun polyurethane nanofibers containing silver, cactus, rosin and Scutellariae Radix. The utilized polyurethane nanofibers containing different composite materials were prepared by a simple dip coating method. The morphology, structure and thermal characteristics of as-prepared composite nanofibers were studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared, Raman spectroscopy and thermogravimetric analysis. The antimicrobial activity of the composite nanofibers was tested against two common food borne pathogenic bacteria, Staphylococcus aureus and Escherichia coli, by the minimum inhibitory concentration method. Our results demonstrated that more pronounced antimicrobial activities were observed for the composite nanofibers. Overall, the fabrication of cheap, stable and effective material with excellent antimicrobial activity can be utilized to inhibit the microbial growth associated with food stuff.     

Optical and electrical properties of p-type Ag-doped ZnO nanostructures

Zn_1−xAg_xO nanoparticles (NPs) (x=0, 0.02, 0.04, and 0.06) were synthesized by a sol–gel method. The synthesized undoped ZnO and Zn_1−xAg_xO-NPs were characterized by X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and UV–visible spectroscopy. The XRD patterns indicated that undoped and Ag-doped ZnO crystallize in a hexagonal wurtzite structure. The TEM images showed ZnO NPs with nearly spherical shapes, with particle size distributed over the nanometer range. Evidence of dopant incorporation is demonstrated in the XPS measurements of the Ag-doped ZnO NPs. The Raman measurements indicated that the undoped and Ag-doped ZnO-NPs had a high crystalline quality. From the result of UV–vis, the band-gap values of prepared undoped and Ag-doped ZnO were found to decrease with an increase in Ag concentration. The obtained undoped and Ag-doped ZnO nanoparticles were used as a source material to grow undoped and Ag-doped ZnO nanowires on n-type Si substrates, using a thermal evaporation set-up. Two probe method results indicated that the Ag-doped ZnO nanowires exhibit p-type properties.     

Diameter control of ultrathin zinc oxide nanofibers synthesized by electrospinning

Electrospinning is a versatile technique, which can be used to generate nanofibers from a rich variety of materials. We investigate the variation of a zinc oxide (ZnO)-polyvinylpyrrolidone (PVP) composite structure in morphology by electrospinning from a series of mixture solutions of ZnO sol–gel and PVP. Calcination conditions for the crystallization of ZnO nanofibers and removal of the PVP component from the ZnO-PVP composite nanofibers were also studied. The progression of the ZnO-PVP composite structure from grains to nanofibers was observed, and ZnO-PVP nanofibers as thin as 29.9 ± 0.8 nm on average were successfully fabricated. The size of the resultant ZnO-PVP composite nanofibers was considerably affected by two parameters: the concentrations of zinc acetate and PVP in the precursor solution. The concentration of zinc acetate particularly influenced the diameter distribution of the ZnO-PVP nanofibers. The ZnO-PVP nanofibers could be subsequently converted into ZnO nanofibers of a pure wurtzite phase via calcination in air at 500°C for 2 h.     

Nanoclay reinforced UV curable waterborne polyurethane hybrids

Waterborne polyurethane (PU)/clay nanocomposites were synthesized by incorporating the chemically modified clay into the main chain of PU by UV cure where modification was made using vinyltrimethoxysilane (VTMS) via sol–gel reaction. It was found that VTMS modified clay gave dual effects of multifunctional cross-link as well as reinforcing filler and significantly augmented hardness, tensile modulus and strength, rubbery modulus, gel content and swelling resistance, glass transition temperature and thermal stability of the waterborne PU.     

Fabrication of multifunctional TiO2–fly ash/polyurethane nanocomposite membrane via electrospinning

In this study, we demonstrate the fabrication of multifunctional composite polyurethane (PU) membrane from a sol gel system containing TiO₂ and fly ash (FA) nanoparticles (NPs). The adsorptive property of FA and photocatalytic property of TiO₂ can introduce different functionalities on PU mat for water purification. Different types of PU nanofiber mats were prepared by varying the composition of NPs in blend solution. FE-SEM, TEM, TGA, XRD, UV–visible spectra, and water contact angle measurement confirmed the incorporation of FA and TiO₂ NPs on/into PU nanofibrous mat. The influence of NPs on PU membrane was evaluated from the adsorption of heavy metals (Hg, Pb), removal of dyes (methylene blue), antibacterial activity, and water flux. The improvement of all these activities is attributed to the adsorptive property of FA and photocatalytic/hydrophilic property of TiO₂ NPs. Therefore, as-synthesized composite membrane can be utilized as an economically friendly filter media for water purification.     

Preparation and characterization of TiO2, ZnO,and TiO2/ZnO nanofilms via sol–gel process

The preparation of the TiO₂, ZnO, and TiO₂/ZnO nanofilms was conducted on glass via sol–gel process. The prepared film was detailedly characterized by means of OM, SEM, XRD, and EDS. The results showed that the obtained pure TiO₂ was composed of nanoparticles. For pure ZnO it consisted of nanoparticles and large agglomerates. Both the microstructural morphology and the crystallization of the prepared TiO₂/ZnO composite film were strongly related to the Ti/Zn ratio in the film. With a Ti/Zn ratio less than 1/1, the composite film was absence of cracks. Poor crystallization was definitely observed for the composite film with Ti/Zn ratio of 3/1 and 1/1. The EDS analysis revealed homogeneous distribution of Ti and Zn elements in the film.     

Polymer/silica nanohybrids by means of tetraethoxysilane sol–gel condensation onto waterborne polyurethane particles

Stable waterborne polyurethane/silica hybrid dispersions were obtained by sol–gel reaction of tetraethoxysilane added to previously synthesized waterborne polyurethane nanodispersions. Two series of polyurethane/silica nanostructures with different silica contents were synthesized using pure polyurethane particles and polyurethane particles previously functionalized with (3-aminopropyl)triethoxysilane (APTES) as colloidal templates. The optimum experimental conditions for tetraethoxysilane sol–gel reaction (T = 75 °C and semi batch polymerization conditions) leading to the formation of silica/polyurethane aqueous nanodispersions were established. The presence of silica was confirmed using TGA, FTIR, ²⁹Si NMR and TEM. TEM images showed an excellent final dispersion of the silica nanoparticles in the polymer matrix when silane functionalized polyurethane nanoparticles were used.     

Value addition to waterborne polyurethane resin by silicone modification for developing high performance coating on aluminum alloy

Silicone–polyurethane waterborne coatings were synthesized using sol–gel technique for protecting aluminum and its alloys. These are derived using polyurethane (PU), hexamethoxymethylmelamine (HMMM) and silicones such as methyltrimethoxysilane (MTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursors. Structural and morphological features of coatings were assessed using Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Performance of the coatings was evaluated using potentiodynamic polarization studies, contact angle measurement, DSC/TGA, UV–vis spectrophotometer, and mechanical tests such as flexibility, pencil hardness test and impact resistance.     

Electrospun polyurethane patch in combination with cedarwood and cobalt nitrate for cardiac applications

The growth in nanotechnology led to the fabrication of scaffold at a low cost with high productivity and high surface area. The present research aims to fabricate a novel cardiac scaffold utilizing polyurethane (PU) added with cedarwood (CW) and cobalt nitrate (CoNO₃) nanofibers. Morphological analysis showed that the mean fiber diameter of the PU nanofibers was reduced owing to the incorporation of CW and CoNO₃. Infrared and thermal analysis revealed the interaction of PU with CW and CoNO₃. Contact angle studies showed that the electrospun PU/CW displayed hydrophobic nature while PU/CW/CoNO₃ showed hydrophilic behavior compared to the pristine PU. The tensile strength of PU nanofibers increased with CW and CoNO₃ addition. Atomic force microscopy analysis depicted that the PU/CW was rougher while the PU/CW/CoNO₃ as smoother surfaces than the pristine PU. According to the coagulation assay data, the blood compatibility of the electrospun composites was enhanced compared to the pristine PU. In addition, PU and its composite nanofibers exhibited non-toxic to human dermal fibroblast cells and improved cell proliferation rates compared to the control plates. To conclude, the improved physicochemical and biological response of the electrospun composites would be putative for cardiac tissue engineering. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48226.     

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     

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     

聚氨酯/纳米氧化锌复合材料研究进展

综述了聚氨酯/纳米氧化锌复合材料的制备方法及研究进展。介绍了纳米氧化锌复合材料力学性能、抗静电性能、紫外屏蔽性能、耐磨与抗腐蚀性能和阻尼减振性能及应用。指出聚氨酯/纳米氧化锌复合材料存在的问题及发展方向。     

Inactivation of pathogenic Klebsiella pneumoniae by CuO/TiO2 nanofibers: A multifunctional nanomaterial via one-step electrospinning

The fabrication and characterization of one-dimensional CuO/TiO₂ nanofibers with high photocatalytic and antibacterial activities are presented. The CuO/TiO₂ nanofibers were prepared by electrospinning of colloid composed of titanium isopropoxide, poly(vinylpyrroliodine) (PVP) and copper nanoparticles and calcination at 700 °C in air for 1 h. The antibacterial activity was tested using Klebsiella pneumoniae as model organism by calculation of the minimum inhibitory concentration (MIC). The obtained CuO/TiO₂ nanofibers showed prominent photocatalytic activity under visible light to degrade reactive black5 and reactive orange16 dyes in aqueous solutions and effectively catalyze K. pneumoniae inactivation. The decomposition process of the cell wall and cell membrane was directly observed by TEM analysis after the exposure of the K. pneumoniae to the nanofibers. Interestingly, the introduced photocatalyst can be reused with the same photocatalytic activity. Overall, the combination of CuO and TiO₂ can be synergistic and resulted in CuO/TiO₂ composite nanofibers having superior photocatalytic and antimicrobial potential to impede K. pneumoniae growth which causes bacterium to die ultimately.     

Preparation and characterization of biodegradable polyurethanes composites filled with silver nanoparticles-decorated graphene

In this study, polyurethane (PU) was synthesized using 4,4,-diphenylmethane diisocyanate (MDI) as a hard segment, polycaprolactone diol (PCL) as the soft segments and 1,4-butandiol (1,4-BD) as a chain extender. Nanosilver/graphene (Ag/G) was added to the PU matrix to prepare Ag/G/PU nanocomposites. EDS, SEM and XRD are used for assaying the silver content and characterization of Ag/G. TEM, FT-IR, XRD and EDS were used to characterize the structure and morphology of the Ag/G/PUs nanocomposites. The TEM results show that Ag/G belongs to sheet structures and is dispersed in a PU matrix. The SEM showed that the strong interfacial adhesion between the Ag/G and PU is indicated. FT-IR spectra analysis shows that the functional group of PU is free of obvious changes by adding a small amount of Ag/G in the PU matrix. XRD results showed that the main crystalline peak (26°) of Ag/G became more apparent with increasing content of Ag/G, and EDS showed that the content of Ag increased with increasing content of Ag/G in the Ag/G/PUs nanocomposites. The thermal stability and mechanical properties of Ag/G/PUs nanocomposites are improved with increasing content of Ag/G. Contact angle and AFM results showed that the hydrophobicity and surface roughness increased with increasing content of Ag/G. Moreover, the Ag/G/PUs nanocomposites exhibit antibacterial activities toward Staphylococcus aureus as well as Escherichia coli and their antibacterial rates increase with increasing Ag/G. In addition, the electrical conductivity measurements showed that both surface and volume resistance of the Ag/G/PUs nanocomposites decreased as the amount of Ag/G increased.     

Fabrication and characterization of silver nanoparticle-incorporated bilayer electrospun–melt-blown micro/nanofibrous membrane

In this study, we fabricated an antifouling bilayered fibrous filter media having micro-nonwoven by melt blowing and nano-nonwoven by electrospinning process. Silver nanoparticle-incorporated polyurethane nanofibers were electrospun on the meltblown fiber of polypropylene. Silver nanoparticles were synthesized in situ in the polyurethane electrospun nanofibers through reduction of silver nitrate. The filter media were characterized by field emission scanning electron microscope, transmission electron microscopy, and X-ray diffraction and energy-dispersive X-ray spectroscopy analyses. The composite membrane showed that a thin layer of electrospun nanofibers improved the filtration efficiency without substantial increase in pressure drop. In situ synthesis of Ag NPs imparted the antibacterial and antifouling characteristics to the membrane.     

Effect of nano ZnO on the phase mixing of polyurethane hybrid dispersions

In the present study series of aqueous polyurethane (PU)/ZnO hybrid dispersions were prepared using dimethylolpropionic acid (bis-MPA) as an ionic center. For this, NCO terminated PU prepolymers with pendent acid groups were prepared first, then different concentrations of nano ZnO powder was incorporated into the PU matrix. The hybrid dispersions were prepared by adding required amount of triethylamine (TEA), water and chain extender. The prepared PU/ZnO hybrid dispersions were casted in a Teflon petri dish and the dried films were used for TGA, DMTA, SEM, gel content and contact angle measurements. The phase mixing behavior was studied from FT-IR peak deconvolution technique and DMTA analysis and the result suggests that phase mixing increases with ZnO content. The DMTA data suggest that the phase mixing and soft segment glass transition increases but storage modulus decreases with increasing with ZnO content. The FT-IR deconvolution result supports to the DMTA analysis. The coating properties like adhesive strength, water absorption, contact angle, gel content and corrosion resistance of the hybrid coatings were also evaluated.     

Mn2O3/TiO2 nanofibers with broad-spectrum antibiotics effect and photocatalytic activity for preliminary stage of water desalination

Composite nanofibers consisting of Mn₂O₃ and TiO₂ were prepared by the electrospinning process, and tested as Gram-class-independent antibacterial agent and photocatalyst for organic pollutants degradation. Initially, electrospinning of a sol–gel consisting of titanium isopropoxide, manganese acetate tetrahydrate and poly(vinyl pyrrolidone) was used to produce hybrid polymeric nanofibers. Calcination of the obtained nanofibers in air at 650 °C led to produce good morphology Mn₂O₃/TiO₂ nanofibers. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the as-spun nanofibers and the calcined product. X-ray powder diffractometry (XRD) analysis was also used to characterize the chemical composition and the crystallographic structure of the sintered nanofibers. The antibacterial activity of Mn₂O₃/TiO₂ nanofibers against Gram negative and Gram positive bacteria was investigated by calculating the minimum inhibitory concentration after treatment with the nanofibers. Investigations revealed that the lowest concentration of Mn₂O₃/TiO₂ nanofibers solution inhibiting the growth of Staphylococcus aureus ATCC 29231 and Escherichia coli ATCC 52922 strains is 0.4 and 0.8 μg/ml, respectively. Incorporation of Mn₂O₃ significantly improved the photodegradation of methylene blue (MB) dye under the visible light irradiation due to enhancing rutile phase formation in the TiO₂ nanofibers matrix.