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1.
In this present study, biodegradable PBAT nanocomposites containing different weight percentages (1, 3, 5, 7, and 10% w/w) of TiO2 nanoparticles were prepared by using solvent casting technique, chloroform as a solvent. The microstructure and morphology of the as‐synthesized poly(butylene adipate‐co‐terephthalate) (PBAT)/TiO2 nanocomposite films were characterized by Fourier‐transform infrared, X‐ray diffraction, scanning electron microscopy, and transmission electron microscope. The thermal degradation of PBAT composites was studied by using thermogravimetric analysis. The mechanical strength of the films was improved by increasing TiO2 concentration. Tensile strength increased from 32.60 to 63.26 MPa, respectively. Barrier properties of the PBAT/TiO2 nanocomposites were investigated by using an oxygen permeability tester. The oxygen permeability (oxygen transmission rate) decreased with increasing the TiO2 nanoparticle concentrations. The PBAT/TiO2 nanocomposite films showed profound antimicrobial activity against both Gram‐positive and Gram‐negative foodborne pathogenic bacteria, namely, Escherichia coli and Staphylococcus aureus, to understand to the zone of inhibition. These results indicated that filler–polymer interaction is important and the role of the TiO2 as a reinforcement in the nanocomposites was evident. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

2.
A novel immunosensor has been developed by self‐assembling Au NPs onto a ferrocene‐branched chitosan/multiwalled carbon nanotubes (CS‐Fc/MWCNTs) modified electrode for the sensitive determination of hepatitis B surface antigen (HBsAg). The formation of CS‐Fc effectively avoids the leakage of Fc and retains its electrochemical activity. Incorporation of MWCNTs and Au NPs into CS‐Fc further increases the electrochemical active Fc in the CS films and provides interactive sites for the immobilization of HBsAb. The morphologies and electrochemistry of the formed biofilm were investigated by using scanning electron microscopy and electrochemical techniques. The immunosensor exhibits a specific response to HBsAg in the range of 1.0–420 ng mL?1. Excellent analytical performance, fabrication reproducibility and operational stability of the proposed immunosensor indicated its promising application in clinical diagnostics.  相似文献   

3.
It is important to develop high performances biodegradable polymers to eliminate the “white pollution” evoked by petroleum‐based polymer. Thermoplastic starch (TPS) with nano‐ellipse configuration was fabricated to reinforce the performances of poly (butylene adipate co‐terephthalate) (PBAT) biocomposites. Effects of tartaric acid (TA) (0.5% wt) on the structure of TPS and compatibility for PBAT were evaluated by Fourier‐transform infrared spectroscopy (FTIR), viscosity and rheological measurement, dynamic mechanical analysis (DMA) and scanning electron microscope (SEM), respectively. They revealed that TA reduced the molecular weight of starch and shear viscosity of TPS were beneficial for TPS dispersing in PBAT matrix with 184‐nm averaged diameter. PBAT/TPS‐TA (70:30 wt%) biocomposite films were blew with different blow‐up ratio. The morphology of films presented that nano‐TPS‐TA wrapped in the PBAT matrix and deformed from ball to capsule feature without agglomeration. Compared with those of PBAT film, the increment in elongation at break of PBAT/TPS‐TA film was 100%. The air permeability and UV‐VIS transmittance of PBAT/TPS‐TA films decreased from 6.92 × 10?9 to 3.72 × 10?9 cm3·cm·cm?2 s?1 Pa?1 and 47.6% to 23.5%, respectively. This study proposed a facile approach to fabricate low‐cost PBAT films with significant improved mechanical, optical, and air barrier properties for commercial application. Mechanism for nanoparticles of TPS‐TA motivated the elevated performances was proposed, synchronously.  相似文献   

4.
Based on the characteristics of polycations of chitosan and glucoamylase, which are oppositely charged, they were successfully alternatingly deposited onto the surface of aldehyde‐modified Fe3O4 nanoparticles by using a layer‐by‐layer ion exchange method to form magnetic carriers to construct multilayer films (designated as Fe3O4@(CS/GA)n). The (CS/GA)n film systems were endowed with the pH‐dependent properties of chitosan as well as the catalytic activity of glucoamylase. The changes in weight loss and surface chemistry, morphology, and magnetic sensitivity were monitored and verified by UV/Vis spectroscopy, zeta potential, TEM, and a vibrating sample magnetometer. Subsequently, the influence of the number of bilayers, storage stability, pH, temperature, and reusability of Fe3O4@(CS/GA)5 biocatalysts on catalytic activity were investigated. The results from characterization and determination remarkably indicate that Fe3O4@(CS/GA)5 presents excellent catalytic activity, storage stability, pH stability, and reusability in comparison with free enzyme. Fe3O4@(CS/GA)5 retained >60 % of its initial activity at 65 °C over 6 h; the optimum temperature and pH also increased to the ranges of 45–65 °C and 2.5–3.5, respectively, and only 27 % activity was lost after 10 cycles. This new strategy simplifies the reaction protocol and improves encapsulation efficiency and catalytic activity for new potential applications in biotechnology.  相似文献   

5.
Polyelectrolyte multilayers assembled from hyaluronic acid (HA) and poly‐l ‐lysine (PLL) are most widely studied showing excellent reservoir characteristics to host molecules of diverse nature; however, thick (HA/PLL)n films are often found cell repellent. By a systematic study of the adhesion and proliferation of various cells as a function of bilayer number “n” a correlation with the mechanical and chemical properties of films is developed. The following cell lines have been studied: mouse 3T3 and L929 fibroblasts, human foreskin primary fibroblasts VH‐Fib, human embryonic kidney HEK‐293, human bone cell line U‐2‐OS, Chinese hamster ovary CHO‐K and mouse embryonic stem cells. All cells adhere and spread well in a narrow “cell‐friendly” window identify in the range of n = 12–15. At n < 12, the film is inhomogeneous and at n > 15, the film is cell repellent for all cell lines. Cellular adhesion correlates with the mechanical properties of the films showing that softer films at higher “n” number exhibiting a significant decrease of the Young's modulus below 100 kPa are weakly adherent to cells. This trend cannot be reversed even by coating a strong cell‐adhesive protein fibronectin onto the film. This indicates that mechanical cues plays a major role for cell behavior, also in respect to biochemical ones.  相似文献   

6.
In this study, novel biodegradable materials were successfully generated, which have excellent mechanical properties in air during usage and storage, but whose structure easily disintegrates when immersed in water. The materials were prepared by melt blending poly(L ‐lactic acid) (PLLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) with a small amount of oligomeric poly(aspartic acid‐co‐lactide) (PAL) as a degradation accelerator. The degradation behavior of the blends was investigated by immersing the blend films in phosphate‐buffered saline (pH = 7.3) at 40 °C. It was shown that the PAL content and composition significantly affected morphology, mechanical properties, and hydrolysis rate of the blends. It was observed that the blends containing PAL with higher molar ratios of L ‐lactyl [LA]/[Asp] had smaller PBAT domain size, showing better mechanical properties when compared with those containing PAL with lower molar ratios of [LA]/[Asp]. The degradation rates of both PLLA and PBAT components in the ternary blends simultaneously became higher for the blends containing PAL with higher molar ratios of [LA]/[Asp]. It was confirmed that the PLLA component and its decomposed materials efficiently catalyze the hydrolytic degradation of the PBAT component, but by contrast that the PBAT component and its decomposed materials do not catalyze the hydrolytic degradation of the PLLA component in the blends. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010  相似文献   

7.
《先进技术聚合物》2018,29(1):61-68
Bio‐based nanocomposites of poly (butylene adipate‐co‐terephthalate) (PBAT)/silver oxide (Ag2O) were prepared by the composite film casting method using chloroform as the solvent. The prepared Ag2O at different ratios (1, 3, 5, 7, and 10 wt%) is incorporated in the PBAT. The PBAT nanocomposite films were subjected to structural, thermal, mechanical, barrier, and antimicrobial properties. The electron micrographs indicated uniform distribution of Ag2O in the PBAT matrix. However, the images indicated agglomeration of Ag2O particles at 10 wt% loading. The thermal stability of the nanocomposite films increased with Ag2O content. The tensile strength and elongation of the composite films were found to be higher than those of PBAT and increased with Ag2O content up to 7 wt%. The PBAT‐based nanocomposite films showed the lower oxygen and water vapor permeability when compared to the PBAT film. Antimicrobial studies were performed against two food pathogenic bacteria, namely, Klebsiella pneumonia and Staphylococcus aureus.  相似文献   

8.
A ferrocene‐labeled high molecular weight coenzyme derivative (PEI‐Fc‐NAD) and a thermostable NAD‐dependent L ‐lysine 6‐dehydrogenase (LysDH) from thermophile Geobacillus stearothermophilus were used to fabricate a reagentless L ‐lysine sensor. Both LysDH and PEI‐Fc‐NAD were immobilized on the surface of a gold electrode by consecutive layer‐by‐layer adsorption (LBL) technique. By the simple LBL method, the reagentless L ‐lysine sensor, with co‐immobilization of the mediator, coenzyme, and enzyme was obtained, which exhibited current response to L ‐lysine without the addition of native coenzyme to the analysis system. The amperometric response of the sensor was dependent on the applied potential, bilayer number of PEI‐Fc‐NAD/LysDH, and substrate concentration. A linear current response, proportional to L ‐lysine concentration in the range of 1–120 mM was observed. The response of the sensor to L ‐lysine was decreased by 30% from the original activity after one month storage.  相似文献   

9.
In an attempt to synthesize antibacterial agents effective against gram‐positive and gram‐negative bacteria, the efficient synthesis of novel bis‐azetidinones ( 3a–j ) has been established. Thus, cycloaddition reaction of substituted bis‐imines with chloroacetylchloride under microwave irradiation in the presence of zeolite yielded bis‐azetidinones ( 3a–j ). Structures of the synthesized compounds have been elucidated on the basis of their elemental analysis and spectral data (IR, 1H‐NMR, 13C‐NMR, and mass spectra). The synthesized bis‐azetidinones were screened for their antibacterial activity against five microorganisms: Bacillus subtilis, Proteus vulgaris, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli. They were found to exhibit good to moderate antibacterial activity.  相似文献   

10.
In this research, thermo‐ and pH‐responsive chitosan‐based porous nanoparticles were prepared by the temperature‐dependent self assembly method. The chitosan‐graft‐poly(N‐isopropylacrylamide) (CS‐g‐PNIPAAm) copolymer solution was prepared through polymerization of N‐isopropylacrylamide (NIPAAm) monomer in the presence of chitosan (CS) solution using cerium ammounium nitrate as the initiator. Then, CS‐g‐PNIPAAm solution was diluted by deionized water and heated to 40 °C for CS‐g‐PNIPAAm self‐assembly. After that, CS‐g‐PNIPAAm assembled to form micelles in which shell layer was CS. Crosslinking agent was used to reinforce the micelle structure to form nanoparticle. The molar ratio of CS/NIPAAm in the feed mixture was changed to investigate its effect on structure, morphology, thermal‐ and pH‐responsive properties of the nanoparticles. TEM images showed that a porous structure of nanoparticles was developed. The synthesized nanoparticles carried positive charges on the surface and exhibited stimuli‐responsive properties, and their mean diameter thus could be manipulated by changing pH value and temperature of the environment. The nanoparticles showed a continuous release of the encapsulated doxycycline hyclate up to 10 days during an in‐vitro release experiment. These porous particles with environmentally sensitive properties are expected to be utilized in hydrophilic drug delivery system. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5126–5136, 2009  相似文献   

11.
We report a simple and effective strategy for fabrication of the nanocomposite containing chitosan (CS) and multiwall carbon nanotube (MWNT) coated on a glassy carbon electrode (GCE). The characterization of the modified electrode (CS‐MWNT/GC) was carried out using scanning electron microscopy (SEM) and UV–vis absorption spectroscopy. The electrochemical behavior of CS‐MWNT/GC electrode was investigated and compared with the electrochemical behavior of chitosan modified GC (CS/GC), multiwalled carbon nanotube modified GC (MWNT/GC) and unmodified GC using cyclic voltammetry (CV) and electron impedance spectroscopy (EIS). The chitosan films are electrochemically inactive; similar background charging currents are observed at bare GC. The chitosan films are permeable to anionic Fe(CN)63?/4? (FC) redox couple. Electrochemical parameters, including apparent diffusion coefficient for the Fe(CN)63?/4? redox probe at FC/CS‐MWNT/GC electrode is comparable to values reported for cast chitosan films. This modified electrode also showed electrocatalytic effect for the simultaneous determination of D‐penicillamine (D‐PA) and tryptophan (Trp). The detection limit of 0.9 μM and 4.0 μM for D‐PA and Trp, respectively, makes this nanocomposite very suitable for determination of them with good sensitivity.  相似文献   

12.
Cellular‐compatible scaffolds were prepared using a three‐dimensional micro‐porous chitosan (CS) non‐woven fabric immobilized by glutaraldehyde (GA), followed by the immobilization of chondroitin‐6‐sulfate (ChS). To characterize the immobilizing process, tensile analysis, and scanning electron microscopy (SEM) were performed. The cell seeding efficiency and proliferation test were evaluated using L929 fibroblasts. The chitosan scaffolds showed high water vapor transmission rate and antibacterial activity. In addition, ChS‐immobilized scaffolds exhibited higher cell seeding efficiency and fibroblasts proliferation. These results demonstrated that the CS non‐woven fabrics grafted with GA and immobilized with ChS could be an appropriate candidate for wound healing and artificial scaffolds in the clinical applications. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

13.
Rare earth (Nd, Y, La, Dy) stearates have been synthesized and used as single component catalysts for the polycondensation of dimethyl terephthalate, adipic acid and 1,4-butanediol for the first time preparing biodegradable poly(butylene adipate-co-terephthalate) (PBAT) with high molecular weight, The microstructures of PBAT were characterized by ^1H NMR spectra. The PBAT exhibits good mechanical properties such as high tensile strength (ca. 20 MPa) and long break elongation (〉700%).  相似文献   

14.
Herein, we present a multifunctional chip based on surface‐enhanced Raman scattering (SERS) that effectively captures, discriminates, and inactivates pathogenic bacteria. The developed SERS chip is made of a silicon wafer decorated with silver nanoparticles and modified with 4‐mercaptophenylboronic acid (4‐MPBA). It was prepared in a straightforward manner by chemical reduction assisted by hydrogen fluoride etching, followed by the conjugation of 4‐MPBA through Ag S bonds. The dominant merits of the fabricated SERS chip include excellent reproducibility with a relative standard deviation (RSD) value smaller than 11.0 %, adaptable bacterial‐capture efficiency (ca. 60 %) at low concentrations (500–2000 CFU mL−1), a low detection limit (down to a concentration of 1.0×102 cells mL−1), and high antibacterial activity (an antibacterial rate of ca. 97 %). The SERS chip enabled sensitive and specific discrimination of Escherichia coli and Staphylococcus aureus from human blood.  相似文献   

15.
The surface modification of hydroxyapatite (HA) nanoparticles by the ring opening polymerization (ROP) of γ‐benzyl‐L ‐glutamate N‐carboxyanhydride (BLG‐NCA) was proposed to prepare the poly(γ‐benzyl‐L ‐glutamate) (PBLG)‐grafted HA nanoparticles (PBLG‐g‐HA) for the first time. HA nanoparticles were firstly treated by 3‐aminopropylthriethoxysilane (APS) and then the terminal amino groups of the modified HA particles initiated the ROP of BLG‐NCA to obtain PBLG‐g‐HA. The process was monitored by XPS and FT‐IR. The surface grafting amounts of PBLG on HA ranging from 12.1 to 43.1% were characterized by thermal gravimetric analysis (TGA). The powder X‐ray diffraction (XRD) analysis confirmed that the ROP only underwent on the surface of HA nanoparticles without changing its bulk properties. The SEM measurement showed that the PBLG‐g‐HA hybrid could form an interpenetrating net structure in the self‐assembly process. The PBLG‐g‐HA hybrid could maintain higher colloid stability than the pure HA nanoparticles. The in vitro cell cultures suggested the cell adhesion ability of PBLG‐g‐HA was much higher than that of pure HA.

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16.
Activation‐free copolymeric films possessing high selectivity to target proteins and low biofouling background are prepared via controlled radical polymerization. The copolymeric films are generated by surface‐initiated activators regenerated by electron transfer atom transfer radical polymerization (SI‐ARGET ATRP) of N‐acryloxysuccinimide (NAS) and oligo(ethylene glycol) methyl ether methacrylate (OEGMEMA) by controlling the molar feed ratio of the two monomers. The formation of copolymeric films is characterized by ellipsometry, contact angle goniometry, FTIR spectroscopy, and X‐ray photoelectron spectroscopy. The prepared copolymeric films are biotinylated without an activation step. Biotin–streptavidin association is employed as a model system to investigate both selective binding and the relevant signal‐to‐noise (S/N) ratio. When the molar feed ratio of NAS and OEGMEMA is 2:8, the copolymeric film is optimized to give the highest S/N ratio (339.8) according to surface plasmon resonance studies. The highly selective bioconjugation is used to generate micropatterns of rhodamine‐conjugated streptavidin on the copolymeric film. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 329–337  相似文献   

17.
Functional polymer/AgNPs nanocomposites have been prepared. Silver nanoparticles (NPs) were synthesized to which polyacrylamide, PAAm, was covalently bound. PAAm was synthesized via a RAFT reaction and carried thiol and carboxylic acid end groups. Thiol was used to bind the polymer to the metal surface and carboxyl for further reactions. The AgNPs were used in a post‐crosslinking reaction with a separately synthesized poly(butyl acrylate‐co‐methyl methacrylate)/polyglycidyl methacrylate core/shell latex bearing epoxy functional groups. Dynamic mechanical analysis showed that the functional AgNPs effectively crosslinked the latex polymer, and that the final product had excellent mechanical strength. Antibacterial tests revealed that the nanocomposite films had strong antibacterial activity against all types of the bacteria and the immobilization of silver NPs by crosslinking retarded the release of silver in comparison to the uncrosslinked ones. With the presented method, it is possible to obtain ductile antibacterial nanocomposites to be used as waterborne functional coatings. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1435–1447  相似文献   

18.
Mesoporous films of platinized carbon nanotube–zirconia–Nafion composite have been used for the immobilization of tris(2,2′‐bipyridyl)ruthenium (II) (Ru(bpy)32+) on an electrode surface to yield a solid‐state electrogenerated chemiluminescence (ECL) sensor. The composite films of Pt–CNT–zirconia–Nafion exhibit much larger pore diameter (3.55 nm) than that of Nafion (2.82 nm) and thus leading to much larger ECL response for tripropylamine (TPA) because of the fast diffusion of the analyte within the films. Due to the conducting and electrocatalytic features of CNTs and Pt nanoparticles, their incorporation into the zirconia–Nafion composite films resulted in the decreased electron transfer resistance within the films. The present ECL sensor based on the Pt–CNT–zirconia–Nafion gave a linear response (R2=0.999) for TPA concentration from 3.0 nM to 1.0 mM with a remarkable detection limit (S/N=3) of 1.0 nM, which is much lower compared to those obtained with the ECL sensors based on other types of sol‐gel ceramic–Nafion composite films such as silica–Nafion and titania–Nafion.  相似文献   

19.
In this research, stimuli‐responsive porous/hollow nanoparticles were prepared by the self‐assembly method. First, chitosan‐graft‐poly(N‐isopropylacrylamide) (CS‐g‐PNIPAAm) copolymers were synthesized through polymerization of N‐isopropylacrylamide (NIPAAm) monomer in the presence of chitosan (CS) solution using ceric ammounium nitrate as the initiator. Then, the CS‐g‐PNIPAAm copolymers were dissolved in the acetic acid aqueous solution and heated to 40 °C to induce their self‐assembly. After CS‐g‐PNIPAAm assembled to form micelles, a cross‐linking agent was used to reinforce the structure to form nanoparticles. The molecular weight of grafted PNIPAAm on CS chains was changed to investigate its effect on the structure, morphology, thermo‐, and pH‐responsive properties of the nanoparticles. TEM images showed that a porous or hollow structure in the interior of nanoparticles was developed, depending on the medium temperature. The synthesized nanoparticles carried positive charges on the surface and exhibited stimuli‐responsive properties, and their mean diameter thus could be manipulated by changing the pH value and temperature of the environment. The nanoparticles showed a continuous release of the encapsulated doxycycline hyclate up to 10 days during an in vitro release experiment. These porous/hollow particles with environmentally sensitive properties are expected to be used in hydrophilic drug delivery system. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2377–2387, 2010  相似文献   

20.
《先进技术聚合物》2018,29(1):481-489
In this study, polyhydroxybutyrate/poly(butyleneadipate‐co‐terephthalate) (PHB/PBAT) nanofibrous membranes were produced by electrospinning the blends of biodegradable PHB and PBAT. The antibacterial hydrophobic nanofiber membranes were obtained by grafting 1‐allylhydantoin and perfluorooctyl acrylate onto the PHB/PBAT membranes. The prepared nanofibrous membranes were chlorinated with chlorine bleach and characterized by scanning electron microscopy, Fourier transform infrared, and thermogravimetric analysis. The chlorinated nanofibrous membranes exhibited efficient antimicrobial activity against Escherichia coli O157:H7 (ATCC 43895) and Staphylococcus aureus (ATCC 6538) with 6.08 and 5.78 log reduction, respectively. The contact angle of this antibacterial membrane was 123.1° ± 1.9°. The treated membranes showed good stability and durability towards UV‐A light exposure and storage. Therefore, our designed antibacterial hydrophobic nanofibrous membranes may have great potential for use in food packaging.  相似文献   

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