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1.
In this study, polymer‐grafted magnetic nanoparticles containing chromium(III) ions incorporated onto Fe3O4/mercaptopropanoic acid‐poly(2‐hydroxyethyl acrylate) was prepared via a simple and in situ method. The obtained magnetic nanocomposite exhibited high catalytic activity and excellent selectivity in direct hydroxylation of benzene in the presence of hydrogen peroxide under solvent‐free condition. The magnetic catalyst could be also separated by an external magnet and reused seven times without any significant loss of activity/selectivity. Due to the Lewis acidity of the Fe3+ groups in the structure of magnetic nanoparticles, the high efficiency of this catalyst is possibly due to the synergetic effect of Cr3+ and Fe3+ groups in the structure of magnetic nanocomposite. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40383.  相似文献   

2.
Conductive electrospun polymer fibers have attracted a great deal of interest in recent years. This study describes the preparation of electrically conductive microfibers composed of polyethersulfone/polydopamine/silver nanoparticles (PES/PDA/Ag NPs). Ag NPs acted as conductive centers, while hydroxyl- and amino-rich functional groups and excellent adhesion properties of PDA served to connect the Ag NPs and PES microfibers. Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) showed that PDA was firmly adhered to PES microfibers. PES/PDA microfibers absorbed considerable amounts of silver ion from AgNO3 solution, resulting in Ag NPs. X-ray diffraction, X-ray photoelectron spectroscopy, and SEM data represented the successful formation of PES/PDA/Ag NPs microfibers. Microfibers with optimal conductivity were obtained using a solution of 2% AgNO3 at pH 9 at 50 °C for 45 min. The electrical resistivity of our PES/PDA/Ag NPs microfibers was only 202 Ω/cm, much lower than that of regular PES microfibers (2.1 × 109 Ω/cm). These results show that the PES/PDA/Ag NPs microfibers are suitable for use as conductive polymer fibers in electromagnetic shielding, and conductivity-sensing applications, and in flexible electronic devices and biosensors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48788.  相似文献   

3.
The goal of this study was to develop doxorubicin conjugate nanoparticles with increased antitumor effects, reduced side effects and the ability to overcome multidrug resistance (MDR). In this regard, folate‐decorated maleilated pullulan–doxorubicin conjugate nanoparticles were developed as carriers for co‐delivery of pyrrolidinedithiocarbamate and doxorubicin (FA‐MP‐DOX/PDTC + DOX NPs). The resultant nanoparticles showed spherical geometry, with an average diameter of 152 nm. The two drugs were released from the nanoparticles in a slow, pH‐dependent sustained release. To test the efficacy of these nanoparticles, in vitro tests including cell viability and folate receptor‐mediated endocytosis were conducted against both A2780 cells and A2780/DOXR cells. Compared to free DOX, the FA‐MP‐DOX/PDTC + DOX NPs showed effective but less potent cytotoxicity against A2780 cells. For A2780/DOXR cells, they showed enhanced cellular uptake, increased targeting capacity and cytotoxicity. These results suggest that co‐delivery of PDTC and DOX may further overcome MDR by transporting an increased amount of DOX within cells in addition to the folate receptor‐mediated endocytosis process. © 2012 Society of Chemical Industry  相似文献   

4.
Stable magnetic nanofluids containing Fe3O4@Polypyrrole (PPy) nanoparticles (NPs) were prepared by using a facile and novel method, in which one-pot route was used. FeCl3·6H2O was applied as the iron source, and the oxidizing agent to produce PPy. Trisodium citrate (Na3cit) was used as the reducing reagent to form Fe3O4 NPs. The as-prepared nanofluid can keep long-term stability. The Fe3O4@PPy NPs can still keep dispersing well after the nanofluid has been standing for 1 month and no sedimentation is found. The polymerization reaction of the pyrrole monomers took place with Fe3+ ions as the initiator, in which these Fe3+ ions remained in the solution adsorbed on the surface of the Fe3O4 NPs. Thus, the core-shell NPs of Fe3O4@PPy were obtained. The particle size of the as-prepared Fe3O4@PPy can be easily controlled from 7 to 30 nm by the polymerization reaction of the pyrrole monomers. The steric stabilization and weight of the NPs affect the stability of the nanofluids. The as-prepared Fe3O4@PPy NPs exhibit superparamagnetic behavior.  相似文献   

5.
《Ceramics International》2022,48(14):19606-19617
The development of ZnO-based dilute magnetic semiconductor nanostructures co-doped with rare-earth and transition metals has attracted substantial attention for spintronics application. In this work, Pr (1%) and Fe (1%, 3%, and 5%) co-doped ZnO nanoparticles (NPs) were synthesized via co-precipitation method, and their structural, morphological, optical, photoluminescence, and magnetic properties were investigated. The single-phase wurtzite hexagonal crystal structure of all samples was detected via X-ray diffraction. Morphological analysis revealed spherical shape of the NPs with an average size in 20–50 nm range. The ultraviolet (UV)–visible measurements showed a redshift in the UV band and a slight change in the bandgap of the co-doped NPs. Fourier transform infrared analysis proved the existence of different functional groups in all synthesized NPs. X-ray photoelectron spectroscopy confirmed that Pr and Fe ions incorporated in the host ZnO lattice exhibit Pr3+ and Fe3+ oxidation states, respectively. Photoluminescence analysis showed that incorporated ions induce characteristic emission bands and structural defects in the synthesized NPs. Magnetic characterization indicated that the ZnO NPs exhibit a diamagnetic nature. However, the (Pr, Fe) co-doped NPs exhibit ferromagnetism at room temperature because of the interactions between Pr3+ and Fe3+ ions and trapped electrons mediated by bound magnetic polarons. Excellent optical and magnetic properties of synthesized samples may render them promising candidates for spintronics applications.  相似文献   

6.
Epoxy polymers, having good mechanical properties and thermal stability, are often used for engineering applications. Their properties can be further enhanced by the addition of iron oxide (Fe3O4) nanoparticles (NPs) as fillers to the resin. In this study, pristine Fe3O4 NPs were functionalized with polydopamine (PDA), (3-glycidoxypropyl)trimethoxysilane (GPTMS), and (3-aminopropyl)trimethoxysilane (APTES). X-ray diffraction and scanning electron microscopy (SEM) were used to study any changes in the crystal structure and size of the NPs while Fourier-Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) were used to ensure the presence of functional groups on the surface. The mechanical properties of the Fe3O4-based nanocomposites generally improved except when reinforced with Fe3O4/PDA. The maximum improvement in tensile strength (∼34%) and fracture toughness (∼13%) were observed for pristine Fe3O4-based nanocomposites. Dynamic mechanical analysis (DMA) showed that the use of any of the treated NPs improved the material's initial storage modulus and had a substantial impact on its dissipation potential. Also, it was observed that the glass transition temperature measurements by DMA and differential scanning calorimetry were below that of pure epoxy. SEM of the cracked surfaces shows that the incorporation of any NPs leads to an enhancement in its thermal and mechanical properties.  相似文献   

7.
Using the principle of geochemistry of fluoride, green and cost effective anion adsorbents were developed for the removal of F? from water systems. The scheme was further applied for the removal of NO3? also. Carboxymethylated starch functionalized through network formation with acrylamide was used as adsorbent, and the resultant hydrogels were loaded with Fe2+ ions to generate anchorage for the anions. Sorption of Fe2+ was studied as a function of different factors such as time, temperature, pH, and ion strength. The network having the highest Fe2+ uptake was loaded with the Fe2+ ions under optimum conditions and used for the sorption of F? and NO3?. High efficiency has been observed for F?, as even up to 100% uptake has been observed within just 10 minutes. The support shows high selectivity for NO3?, which was used as anion reference. Thermodynamics of sorption confirms low order and low energy processes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007  相似文献   

8.
This research describes a colorimetric assay for Cu (II) ions that is highly selective over other metal ions. It is based on the measurement of changes in the surface plasmon resonance absorbance (at 525 nm) of gold nanoparticles (Au NPs) modified with 1,7-diaza-15-crown-5 (Crown-Au NPs). The unique structure of crown ethers and presence of heteroatoms enable the crown-Au NPs to recognize very low concentrations of Cu (II) ions. After aggregation, the surface plasmon absorption band has a red shift so that the nanoparticle solution shows a violet color. The TEM images data show that this color change is a result of crown-Au NPs aggregation upon addition of Cu (II), In contrast, other metal ions Al3+, Ca2+, Cd2+, Co2+, Cr3+, Ag+, Fe2+, Fe3+, Hg2+, K+, Mg2+, Mn2+, Na+, Ni2+, Pb2+, and Zn2+ do not aggregate. The recognition mechanism is attributed to the formation of a sandwich (2+1) between the Cu (II) ion and two diaza-15-crown-5 moieties that are attached to separate nanoparticles. This simple and fast method can be used to determine the Cu (II) ions with a detection limit as low as 200 nM.  相似文献   

9.
To increase the efficacy of doxorubicin in induction of apoptosis, pH-responsive nanocarriers with an average particle size of 20 nm by using chitosan-polymethacrylic acid (CTS-PMAA) shells and Fe3O4 cores via in situ polymerization approach were synthesized. Doxorubicin hydrochloride (DOX) was loaded effectively to nanocarrier through electrostatic interactions and strong hydrogen banding. The cumulative release of DOX-loaded nanoparticles was pH dependent with a maximum release rate at pH 5.8. In vitro cytotoxicity assay revealed the biocompatibility of blank nanocarrier and superior anticancer performance of DOX-loaded nanoparticles verified by DAPI staining and MTT assay tests.  相似文献   

10.
Surfactin is one of the most important lipopeptide biosurfactants obtained by biocatalysts of Bacillus subtilis. The aim of this study was to isolate surfactin-producing bacilli from native soils of the country (Iran), investigate their properties, convert surfactin to surfactin micelles, determine the properties of surfactin micelles and investigate the effect of starch-coated Fe0 and Fe3+ nanoparticles on the production of surfactin from B. subtilis. To do so, 20 bacilli were isolated from the native soil sample by heat shock method and genome sequenced by SrRNA16 method. The samples with strong β-hemolysis activity were screened as surfactant-producing strains. Two species of 61 and 63 (B. subtilis subspecies. Inaquosorum) were selected and examined by quantitative and qualitative screening tests such as hemolysis activity, surfactin production, droplet aggregation, emulsifying activity, and surface tension reduction in MSM medium containing Fe0 and Fe3+ nanoparticles. Surfactin was converted to surfactin micelles by sonication and confirmed by SEM. The antimicrobial and emulsifying activity and surface tension reduction of surfactin micelles were investigated. According to the results, the surface tension reduction of surfactin micelles was greater than that of surfactin. The strain 61 (99.7%) culture in 5 L bioreactors containing Fe3+ nanoparticles produced more surfactin than culture of the same strain without nanoparticles. This study presents an efficient method to increase the biosynthesis of microbial metabolites.  相似文献   

11.
Cobalt oxide nanoparticles@nitrogen-doped reduced graphene oxide (Co3O4@N-rGO) composite and nitrogen-doped graphene dots (N-GDs) were synthesized by a one-pot simple hydrothermal method. The average sizes of the synthesized bare cobalt oxide nanoparticles (Co3O4 NPs) and Co3O4 NPs in the Co3O4@N-rGO composite were around 22 and 24 nm, respectively with an interlayer distance of 0.21 nm, as calculated using the XRD patterns. The Co3O4@N-rGO electrode exhibits superior capacitive performance with a high capability of about 450 F g?1 at a current density of 1 A g?1 and has excellent cyclic stability, even after 1000 cycles of GCD at a current density of 4 A g?1. The obtained N-GDs exhibited high sensitivity and selectivity towards Fe2+ and Fe3+, the limit of detection was as low as 1.1 and 1.0 μM, respectively, representing high sensitivity to Fe2+ and Fe3+. Besides, the N-GDs was applied for bio-imaging. We found that N-GDs were suitable candidates for differential staining applications in yeast cells with good cell permeability and localization with negligible cytotoxicity. Hence, N-GDs may find dual utility as probes for the detection of cellular pools of metal ions (Fe3+/Fe2+) and also for early detection of opportunistic yeast infections in biological samples.  相似文献   

12.
《Dyes and Pigments》2012,92(3):332-339
Two novel tetraester- and PAMAM-branched perylene diimides were synthesized and configured as “fluorophore-spacer-receptor” systems based on photoinduced electron transfer. Due to their long alkylester and alkylamine terminal groups the examined compounds were well soluble in organic solvents. Photophysical characteristics of the dyes were investigated in DMF and water/DMF (1:1, v/v) solution. The ability of the synthesized perylene diimides to detect cations was evaluated by the changes in their fluorescence intensity in the presence of metal ions (Zn2+, Co2+, Cu2+, Fe3+, Pb2+, Hg2+, Ag+ and Ni2+) and protons. The dyes under study displayed “off–on” switching in its fluorescence as a function of pH, which is attributed to disallowing photoinduced electron transfer from the receptor moiety to the fluorophore. PAMAM-branched dye displayed a good pH sensor activity (FE = 6.4), however the pH sensing ability of tetraester was substantially higher (FE = 184). In the presence of Cu2+ and Pb2+ ions tetraester quenched its fluorescence intensity (FQ = 22 and 12 respectively), while PAMAM-branched dye enhanced its fluorescence intensity with pronounced selectivity to Cu2+ and Fe3+ (FE = 3.2 and 4.9, respectively). The results obtained indicate the potential of the novel compounds as fluorescent detectors for metal ions with pronounced selectivity towards Cu2+, Pb2+ and Fe3+ ions and highly efficient “off–on” pH switches, especially a tetraester-branched perylene diimide.  相似文献   

13.
Zn1-xFexO nanoparticles with Fe doping content from 0 % to 6 % were fabricated by a facile auto combustion method. SEM, XRD, PL and XPS were carried out to characterize the morphologies, structures, optical properties and surface chemical states of the samples. The photocatalytic properties were also investigated toward Methyl Orange (MO) degradation. It was found that the maximum photocatalytic activity was obtained by 4 % Fe-doped ZnO nanoparticles, which was ascribed to the highest ratio of Fe2+/Fe3+. The experimental results and DFT calculations indicated that Fe could effectively affect the photocatalytic activity of ZnO nanoparticles, dependent on Fe2+/Fe3+ ratio and doping contents. Furthermore, a conceivable mechanism of band gap structure and carrier transfer of Fe2+/Fe3+ co-existed Zn1-xFexO was proposed according to experimental analyses and theory calculations.  相似文献   

14.
Co‐precipitation from a solution of ferrous/ferric mixed salt with the ratio of Fe2+:Fe3+ = 1:2 in air atmosphere is not a reliable method to synthesize magnetite (Fe3O4) nanoparticles because of the fact that Fe2+ oxidizes to Fe3+ and the molar ratio of Fe2+:Fe3+ changes. Therefore, the phase composition changes from magnetite to maghemite (γ‐Fe2O3). The influence of the initial molar ratio of Fe2+:Fe3+ on the phase composition of nanoparticles, their crystallinity and magnetic properties was studied. Experimental data from XRD, FTIR, SEM, and VSM reveal that the appropriate method to synthesize magnetite nanoparticles is reverse precipitation from only ferrous salt. It is found that by decreasing the synthesis temperature and by increasing the concentration of alkaline solution and the ratio of Fe2+:Fe3+ the crystallinity and the specific saturation magnetization (σs) are increased.  相似文献   

15.
Two novel tetraester- and PAMAM-branched perylene diimides were synthesized and configured as “fluorophore-spacer-receptor” systems based on photoinduced electron transfer. Due to their long alkylester and alkylamine terminal groups the examined compounds were well soluble in organic solvents. Photophysical characteristics of the dyes were investigated in DMF and water/DMF (1:1, v/v) solution. The ability of the synthesized perylene diimides to detect cations was evaluated by the changes in their fluorescence intensity in the presence of metal ions (Zn2+, Co2+, Cu2+, Fe3+, Pb2+, Hg2+, Ag+ and Ni2+) and protons. The dyes under study displayed “off-on” switching in its fluorescence as a function of pH, which is attributed to disallowing photoinduced electron transfer from the receptor moiety to the fluorophore. PAMAM-branched dye displayed a good pH sensor activity (FE = 6.4), however the pH sensing ability of tetraester was substantially higher (FE = 184). In the presence of Cu2+ and Pb2+ ions tetraester quenched its fluorescence intensity (FQ = 22 and 12 respectively), while PAMAM-branched dye enhanced its fluorescence intensity with pronounced selectivity to Cu2+ and Fe3+ (FE = 3.2 and 4.9, respectively). The results obtained indicate the potential of the novel compounds as fluorescent detectors for metal ions with pronounced selectivity towards Cu2+, Pb2+ and Fe3+ ions and highly efficient “off-on” pH switches, especially a tetraester-branched perylene diimide.  相似文献   

16.
A colorimetric and ‘‘turn-on” fluorescent chemosensor Rho-Fe3O4@SiO2 for Hg2+ in which N-(rhodamine-6G)lactam-ethylenediamine (Rho-en) is conjugated with the magnetic core-shell Fe3O4@SiO2 NPs has been strategically designed and synthesized. The final product was characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectra (FTIR) and UV-visible absorption and fluorescence emission. Fluorescence and UV-visible spectra results showed that the resultant multifunctional nanoparticles Rho-Fe3O4@SiO2 exhibited selective ‘turn-on’ type fluorescent enhancements and distinct color changes with Hg2+. The selectivity of the Rho-Fe3O4@SiO2 for Hg(II) ion is better than that of the Rho-en in the same conditions. In addition, the presence of magnetic Fe3O4 nanoparticles in the sensor Rho-Fe3O4@SiO2 NPs would also facilitate the magnetic separation of the Hg(II)-Rho-Fe3O4@SiO2 from the solution.  相似文献   

17.
A magnetic polypeptide nanocomposite with pH and near-infrared (NIR) dual responsiveness was developed as a drug carrier for cancer therapy, which was prepared through the self-assembly of Fe3O4 superparamagnetic nanoparticles, poly(aspartic acid) derivative (mPEG-g-PDAEAIM) and doxorubicin (DOX) in water. Fe3O4 nanoparticles were prepared to provide the superparamagnetic core of nanocomposites for tumor targeting via chemical co-precipitation. The protonable imidazole groups of mPEG-g-PDAEAIM with a pKa of ~7 were accountable for the pH-responsiveness of nanocomposites. The photothermal effect of nanocomposites under the irradiation of NIR laser was induced via the interactions between dopamine groups of mPEG-g-PDAEAIM and Fe3O4 superparamagnetic nanoparticles to trigger the drug release. NMR, FT-IR, TEM, hysteresis loop analysis and MRI were utilized to characterize the materials. The DOX loaded nanocomposites exhibited pH-responsive and NIR dependent on/off switchable release profiles. The nanocomposites without drug loading (Fe3O4@mPEG-g-PDAEAIM) showed excellent biocompatibility while DOX loaded nanocomposites caused MCF-7 cells’ apoptosis due to the photothermal/chemotherapy combination effects. Overall, the pH and near-infrared dual responsive magnetic nanocomposite had a great potential for cancer therapy.  相似文献   

18.
In this paper, we attempted to synthesize a hybrid nanostructure by the incorporation of Au nanoparticles (NPs) with polymer-coated Fe3O4 microspheres. Also, Au NPs on 3-aminopropyl triethylsilane (APTS)-modified Fe3O4@SiO2 and Fe3O4@polymer microspheres were synthesized to assess the catalytic activity of Au NPs on Fe3O4@polymer microspheres for the reduction of 4-nitrophenol. It was found that Au NPs on Fe3O4@polymer catalysts showed higher catalytic activity and recyclability than other APTS-modified catalysts.  相似文献   

19.
Cobalt–zinc ferrite nanoparticles (NPs) substituted with three different metals, Co0.5Zn0.5RexFe2-xO4 (RE = Ce, Dy, and Y; 0.00?≤?x?≤?0.05) were prepared hydrothermally. Fourier Transform-Infrared (FT-IR) Spectroscopy, X-ray powder diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) coupled with energy-dispersive X-ray spectroscopy (EDX) and Vibrating Sample Magnetometry (VSM) analyzed the products. The formation of cubic phase of spinel Co-Zn ferrite NPs were confirmed through XRD, FT-IR and FE-SEM techniques. The structural investigation of NPs by XRD revealed that the lattice parameter "a" decreases with the introduction of the RE in the ferrite structure by the substitution of Fe3+ by RE ions. The different magnetic parameters of Co0.5Zn0.5RexFe2-xO4 (RE = Ce, Dy, and Y; 0.00?≤?x?≤?0.05) NPs such as the saturation magnetization, coercivity, remanence, and magnetic moment were calculated and discussed in relation to structure and microstructure properties. M (H) hysteresis curves indicated that the samples exhibit superparamagnetic nature at room temperature. A slight improvement in the magnetization was obtained especially for the Ce- and Y-substituted Co0.5Zn0.5Fe2O4 (CZF) NPs at a certain RE level. However, the case Dy-substituted CZF products showed a sharp decrease in the magnetization with x?>?0.01. The results are mostly ascribed to the substitution of smaller Fe3+ ions with larger RE3+ ions.  相似文献   

20.
A pH-responsive polymer derived from polyethyleneimine with zwitterionic function was used as a shell around super paramagnetic iron oxide nanoparticles (SPIONs), to introduce an efficient drug carrier for cancer drug delivery and imaging. Core–shell magnetic Fe3O4@FA-PEI-SUC (SUC: Succinate conjugated) nanoparticles were attained and characterized. Right chemical attachments, 61.34% modification of primary amino groups of poly(ethyleneimine) (PEI) in PEI–SUC, spherical shape, core–shell structure, crystal structure of SPIONs, 18.23% polymer coating of NPs, 8% decrease in magnetization following polymer coating around SPIONs, doxorubicin loading efficiency 85.19%, two times more released amount in acidic pH, and proper toxicity results were obtained by different analysis methods.  相似文献   

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