Summary: Surface‐enhanced Raman scattering (SERS)‐active substrates with high enhancement were prepared by an in situ reduction method. Novel silver/poly(vinyl alcohol) (PVA) nanocomposite films were obtained, in which the silver nitrate, poly(γ‐glutamic acid) (PGA), and PVA acted as precursor, stabilizer, and polyol reducant, respectively. The UV‐visible spectra of the as‐fabricated films showed that the surface plasmon resonance (SPR) absorption band was narrow and of a stronger intensity, which indicates that the Ag nanoparticle size distribution on the substrate was highly uniform. This finding was further confirmed by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and field‐emission scanning electron microscope (FE‐SEM) measurements. It was found that a PGA‐stabilized PVA nanocomposite film revealed the presence of well‐dispersed spherical silver nanoparticles with an average diameter of 90 nm. The new substrate presents high SERS enhancement and the enhanced factor is estimated to be 106 for the detection of benzoic acid.
The Raman scattering enhancement factor for the Raman spectra of benzoic acid on the various nanocomposite films. 相似文献
Super porous gum Arabic (GA) cryogels were synthesized by crosslinking of natural GA with divinyl sulfone at cryogenic conditions, −20°C for potential biomedical applications. Humic acid (HA) nanoparticles were also prepared by using degradable and biocompatible crosslinkers such as trimethylolpropane triglycidyl ether, poly(ethylene glycol) diglycidyl ether, and trisodium trimetaphosphate in a single step and then entrapped within GA cryogel network as GA/HA particle cryogel. Furthermore, GA/HA cryogel was used as a template for Ag, Cu, and Fe nanoparticle preparation, and their antimicrobial properties were tested against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis strains. The minimum inhibition concentration values of Ag and Cu nanoparticle‐loaded GA/HA cryogel composites were determined as 10 mg mL−1. Furthermore, the blood compatibility tests such as hemolysis and blood clotting indexes were determined for GA cryogels and found to be more compatible with 0.08 ± 0.01% hemolysis and 89.4 ± 6.1 blood clotting values, whereas the hemolysis of the Ag, Cu, and Fe nanoparticle‐loaded GA/HA Ag, Cu, and Fe metal nanoparticle cryogel composites decreased in the order of Fe > Cu > Ag nanoparticles. 相似文献
β‐Cyclodextrin functionalized graphene/Ag nanocomposite (β‐CD/GN/Ag) was prepared via a one‐step microwave treatment of a mixture of graphene oxide and AgNO3. β‐CD/GN/Ag was employed as an enhanced element for the sensitive determination of 4‐nitrophenol. A wide linear response to 4‐nitrophenol in the concentration ranges of 1.0×10?8–1.0×10?7 mol/L, and 1.0×10?7–1.5×10?3 mol/L was achieved, with a low detection limit of 8.9×10?10 mol/L (S/N=3). The mechanism and the heterogeneous electron transfer kinetics of the 4‐nitrophenol reduction were discussed according to the rotating disk electrode experiments. Furthermore, the sensing platform has been applied to the determination of 4‐nitrophenol in real samples. 相似文献
MOF-5 that sometimes called IRMOF-1 has been intensively studied in recent years to develop efficient photocatalyst to degrade refractory organics and inactivate bacteria for wastewater treatment. In the present work, Ag/Ag3PO4 nanoparticles incorporated in IRMOF-1 was successfully prepared via hydrothermal approach. The antibacterial activity of synthesized materials (IRMOF-1, Ag/Ag3PO4 nanoparticles and Ag/Ag3PO4-IRMOF-1 nanocomposite was compared against two types of bacteria (Escherichia coli (E. coil) as Gram negative and Staphylococcus aureus (S. aureus) as Gram-positive bacteria). The deactivation of the bacteria by the prepared material was measured in the dark and under visible light irradiation. The antibacterial activity of synthesized samples was investigated by determining the minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), growth inhibition assay and inhibition zone. The Ag/Ag3PO4-IRMOF-1 nanocomposite exhibited stronger antibacterial activities than the Ag/Ag3PO4 nanoparticles and IRMOF-1 at all tested bacteria types. Based on inhibition zone, without any light irradiation, Ag/Ag3PO4-IRMOF-1 nanocomposite showed activity toward E. coil, but in presence of light nanocomposite depicted activity toward S. aureus. The results demonstrated that antibacterial activity of all synthesized samples in the dark and light against S. aureus bacteria was more than E. coil bacteria. The antibacterial activity mechanism was due to sustained-release of silver ions in the dark and reactive oxygen species (ROS) under visible light. The bioactivity of IRMOF-1 was related to the degradation of the its structure and the release of Zn2+ ions into the culture medium that bind to the cell wall and deactivation bacteria. 相似文献
Active surface-enhanced Raman scattering (SERS) silver nanoparticles substrate was prepared by multiple depositions of Ag nanoparticles on glass slides. The substrate is based on five depositions of Ag nanoparticles on 3-aminopropyl-trimetoxisilane (APTMS) modified glass slides, using APTMS sol–gel as linker molecules between silver layers. The SERS performance of the substrate was investigated using 4-aminobenzenethiol (4-ABT) as Raman probe molecule. The spectral analyses reveal a 4-ABT Raman signal enhancement of band intensities, which allow the detection of this compound in different solutions. The average SERS intensity decreases significantly in 4-ABT diluted solutions (from 10−4 to 10−6 mol L−1), but the compound may still be detected with high signal/noise ratio. The obtained results demonstrate that the Ag nanoparticles sensor has a great potential as SERS substrate. 相似文献
A nanocomposite gel with a uniform porous structure and well‐controlled compositions prepared by mixing three‐dimensional graphene material with an ionic liquid, 1‐butyl‐3‐methylimidazolium hexafluorophosphate, is used for nitric oxide detection. It shows a fast response of less than 4 seconds, an excellent sensitivity of 11.2 µA cm−2 (µmol/L)−1 and an extremely low detection limit of 16 nM with a signal‐to‐noise ratio of 3 (S/N=3), a performance superior to that of reported works based on carbon nanotubes and nanoparticles. The high sensitivity is attributed to the large electroactive surface area of the graphene gel nanocomposite towards nitric oxide oxidation. The electrochemical behavior of the gel nanocomposite is investigated and explained. 相似文献
A novel electrochemical sensor on ZIF-8 nanocomposites (Ag/ZnO/ZIF-8) was developed to analyze the mercury ions (Hg2+). The ZIF-8 materials are one of the 3-dimensional porous metal-organic frameworks with highly accessible pores and great surface area. The ZIF-8 nanocomposites were prepared through simple sol-gel methods and their physio-chemical properties were characterized via different analytical analyses. As a result of cyclic voltammetry, Ag/ZnO/ZIF-8 exhibited a better electrocatalytic behavior towards the detection of mercury ions (Hg2+). Furthermore, the composite modified electrode was then inspected as a sensor for DPV detection of mercury ions. The nanocomposite sensor performed a wide linear range from 0.5 μM to 140 μM with a low detection limit of 40 nM, and high sensitivity of 56.06 μA μM−1 cm−2. Moreover, the ZIF-8 composite sensor showed a higher selectivity toward the detection of mercury ions (Hg2+). The real-time applications of the ZIF-8 composites sensor were inspected in various samples with good sensitivity. 相似文献
Visible‐light‐driven plasmonic photocatalyst Ag‐TiO2 nanocomposite hollow spheres are prepared by a template‐free chemically‐induced self‐transformation strategy under microwave‐hydrothermal conditions, followed by a photochemical reduction process under xenon lamp irradiation. The prepared samples are characterized by using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, N2 adsorption‐desorption isotherms, X‐ray photoelectron spectroscopy, UV/Vis and Raman spectroscopy. Production of ?OH radicals on the surface of visible‐light illuminated TiO2 was detected by using a photoluminescence method with terephthalic acid as the probe molecule. The photocatalytic activity of as‐prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) aqueous solution at ambient temperature under visible‐light irradiation. The results show that the surface plasmon absorption band of the silver nanoparticles supported on the TiO2 hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag‐TiO2 nanocomposite sample was observed. The prepared nanocomposite hollow spheres exhibits a highly visible‐light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of pure TiO2 and commercial Degussa P25 (P25) powders. Especially, the as‐prepared Ag‐TiO2 nanocomposite hollow spheres at the nominal atomic ratio of silver to titanium ( R ) of 2 showed the highest photocatalytic activity, which exceeds that of P25 by a factor of more than 2. 相似文献
In this paper, we report a feasible protocol for the preparation of [1]benzopyranopyrido[d]pyrimidines via expeditious sonochemical route. The reaction efficiency was evaluated by influence of several parameters including sonication power, sonication time, different solvents, and using porous graphene/MoO3 nanocomposite as catalyst, for the first time. The effect of the ultrasonication comparing with the conventional heating on the synthesis of the titled compounds shows that the ultrasonic irradiation is required to rich the cyclized products. The structural properties of porous graphene/MoO3 nanocomposite were determined by Fourier transform infrared spectroscopy (FT‐IR), powder X‐ray diffractometry (XRD), scanning electron microscope (SEM), Raman spectroscopy, and also by TGA analysis. Confirmation of the structures of compounds 4a – 4h were also established with IR, 1H NMR, and 13C NMR spectroscopic data and also by elemental analyses. 相似文献
