We describe an exciting opportunity for Metal-Enhanced Fluorescence (MEF)-based surface assays using an angular-ratiometric approach to the observed enhanced emission from fluorophores in close proximity to silver colloids deposited on glass substrates. This approach utilizes the radiationless energy transfer (coupling) between the excited states of the fluorophore and the induced surface plasmons of the silver colloids, and the subsequent angular-dependent fluorescence emission from the fluorophore-silver colloid system. Since MEF is related to surface plasmons' ability to scatter light, angular-dependent light scattering from three different silvered surfaces and glass substrates were investigated using two common excitation angles, 45 and 90 degrees . The scattered light from silvered surfaces with a high loading was observed at wider angles on both sides of the glass substrates, while forward scattering (from the back of the glass) was dominant for the silvered surfaces with low loading, as explained by both Mie and Rayleigh theories. When silver colloids were placed between the fluorophore and glass interface, the coupled fluorescence emission through the higher refractive index glass (and in air), increased in an angular-dependent fashion, following closely the angular-dependent light scattering pattern of the silver colloids themselves. Similar observations for fluorescence emission from fluorophores deposited onto glass surfaces alone were made, but at much narrower angles on both sides of the fluorophore-glass interface and were simply explained by Lambert's cosine law. As the loading of silver on glass was increased, the enhanced fluorescence emission was observed at wider angles (towards 0 and 180 degrees ) at both sides of the silvered surfaces. Glass surfaces without silver colloids were used as control samples to demonstrate the benefits of MEF for enhancing fluorescence signatures in an elegant, angular-dependent fashion. Finally, the utility of the angular-dependent MEF phenomenon for intensity-based angular-ratiometric surface assays is demonstrated. 相似文献
Magnesium has been suggested as a potential biodegradable metal for the usage as orthopaedic implants. However, high degradation rate in physiological environment remains the biggest challenge, impeding wide clinical application of magnesium‐based biomaterials. In order to reduce its degradation rate and improve the biocompatibility, micro‐arc oxidation coating doped with HA particles (MAO‐HA) was applied as the inner coating, and polydopamine (PDA) film was synthesized by dopamine self‐polymerization as the outer coating. The microstructure evolution of the coating was characterized using scanning electron microscopy (SEM), atomic force microscope (AFM), X‐ray diffraction analyses (XRD), Fourier transform infrared spectroscopy (FT‐IR), and X‐ray photoelectron spectroscopy (XPS). The results showed that PDA film had covered the entire surface of MAO‐HA coating and the pore size of MAO‐HA coating decreased. The root mean square (RMS) roughness of PDA/MAO‐HA coatings was approximately 106.46 nm, which was closer to the optimum surface roughness for cellular attachment as compared with MAO‐HA coatings. Contact angle measurement indicated that the surface wettability had been transformed from hydrophobic to hydrophilic due to the introduction of PDA. The PDA/MAO‐HA coatings exhibited better corrosion resistance in vitro, with the self‐corrosion potential increasing by 150 mV and the corrosion current density decreasing from 2.09 × 10?5 A/cm 2 to 1.46 × 10?6 A/cm 2 . In hydrogen evolution tests, the corrosion rates of the samples coated with PDA/MAO‐HA and MAO‐HA were 4.40 and 5.95 mm/y, respectively. MTS assay test and cell‐surface interactions experiment demonstrated that PDA/MAO‐HA coatings exhibited good cellular compatibility and could promote the adhesion and proliferation of MC3T3‐E1 cells. 相似文献
Summary: Silvered polyimide films have been fabricated by direct ion exchange of a damp‐dry poly(amic acid) film with an aqueous silver solution such as silver nitrate. Thermal curing of the silver(I )‐containing films under tension leads to cycloimidization of the poly(amic acid) into polyimide with a concomitant silver(I ) reduction and aggregation at both film sides to give reflective and conductive double‐surface‐silvered polyimide films. The metallized films retain the essential properties of the parent polyimide.
Surface morphology of the prepared double‐surface‐silvered polyimide films. 相似文献
For the construction of high‐performance biosensor, it is important to interface bioreceptors with the sensor surface densely and in the optimal orientation. Herein, a simple surface modification method that can optimally immobilize antibodies onto various kinds of surfaces is reported. For the surface modification, a mixture of polydopamine (PDA) and protein G was employed. PDA is a representative mussel‐inspired polymer, and protein G is an immunoglobulin‐binding protein that enables an antibody to have an optimal orientation. The surface characteristics of PDA/Protein G mixture‐coated substrates are analyzed and the PDA/protein G ratio is optimized to maximize the antibody binding efficiency. Moreover, the antibody‐immobilized substrates are applied to the detection of influenza viruses with the naked eye, providing a detection limit of 2.9 × 103 pfu mL‐1. Importantly, the several substrates (glass, SiO2, Si, Al2O3, polyethylene terephthalate, polyethylene, polypropylene, and paper) can be modified by simple incubation with the mixture of PDA/protein G, and then the anti‐influenza A H1N1 antibodies can be immobilized on the substrates successfully. Regardless of the substrate, the influenza viruses are detectable after the sandwich immunoreaction and silver enhancement procedure. It is anticipated that the developed PDA/protein G coating method will extend the range of applicable materials for biosensing. 相似文献
Silver nanoparticles (AgNPs) were deposited onto the monodispersed carboxylic polystyrene (CPS) spheres by an improved in situ reduction method. The size and coverage density of the AgNPs on the surface of CPS spheres could be easily tailored by tuning the concentrations of carboxylic functional groups and silver precursor. The morphologies and structures of the resulting CPS/Ag hybrid particles were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), UV‐Vis‐NIR spectrometer and X‐ray photoelectron spectroscopy (XPS), etc. The surface enhanced Raman scattering (SERS) performances of the resulting uniform CPS/Ag hybrid particles were investigated using 4‐aminobenzenethiol (4‐ABT) as the probe molecule. The optimized CPS/Ag hybrid particles show high enhancement factor (EF) of 2.71×107, low limit of detection (LOD) of 10?10 m and good reproducibility with relative standard deviation (RSD) of 9.64 %. The good SERS improvement properties demonstrate these hybrid particles could be employed as simple and effective substrates in the SERS spectroscopy. 相似文献
The use of an electrochemical reactor operated under different flow conditions to deposit silver from aqueous AgNO(3) solutions and tartaric acid as an organic additive on a commercial activated carbon with ultimate bactericidal applications in water purification processes is presented. The characterization of carbon/silver samples was studied by BET, FTIR, X-ray diffraction, XPS, and SEM techniques. The bactericidal activity of the carbon/silver samples was tested on drinking water samples inoculated with E. coli. A reduction of carbon surface area was detected and was caused by increased amounts of silver deposited on carbon samples. Adherent silver deposits were obtained on the carbon/silver samples. X-ray diffraction studies of carbon with electrodeposited silver showed two different preferential deposition planes, [111] and [220]. The FTIR results confirm the presence of carboxyl, phenolic, quinone, and ether surface groups. The XPS results suggest the formation of Ag(2)O and AgO surface species and confirm the reduction of silver to the metallic form. Antimicrobial activity toward E. coli indicated reductions by up to 7 orders of magnitude in the log CFU/mL in just 10 min contact time and for silver contents of 2.47 wt%. 相似文献