Abstract:In metal-enhanced fluorescence (MEF), the localized surface plasmon resonances of metallic nanostructures amplify the absorption of excitation light and assist in radiating the consequent fluorescence of nearby molecules to the far-field. This effect is at the base of various technologies that have strong impact on fields such as optics, medical diagnostics, and biotechnology. Among possible emission bands, those in the near-infrared (NIR) are particularly intriguing and widely used in proteomics and genomics … Show more
“…The high-energy charges will transfer from the S * to S 0 directly, increasing the probability of recombination between the electrons and the holes. This charge transfer process will highly enhance the fluorescence radiation in R6G 44, 45 . This analysis above gives a reasonable explanation to the relationship between the thickness of shells and fluorescence noises observed in experiments.Figure 9Schematic diagram of the surface resonance charge transfer.…”
One of the main challenges for highly sensitive surface-enhanced Raman scattering (SERS) detection is the noise interference of fluorescence signals arising from the analyte molecules. Here we used three types of gold nanostars (GNSs) SERS probes treated by different surface modification methods to reveal the simultaneously existed Raman scattering enhancement and inhibiting fluorescence behaviors during the SERS detection process. As the distance between the metal nanostructures and the analyte molecules can be well controlled by these three surface modification methods, we demonstrated that the fluorescence signals can be either quenched or enhanced during the detection. We found that fluorescence quenching will occur when analyte molecules are closely contacted to the surface of GNSs, leading to a ~100 fold enhancement of the SERS sensitivity. An optimized Raman signal detection limit, as low as the level of 10−11 M, were achieved when Rhodamine 6 G were used as the analyte. The presented fluorescence-free GNSs SERS substrates with plentiful hot spots and controllable surface plasmon resonance wavelengths, fabricated using a cost-effective self-assembling method, can be very competitive candidates for high-sensitive SERS applications.
“…The high-energy charges will transfer from the S * to S 0 directly, increasing the probability of recombination between the electrons and the holes. This charge transfer process will highly enhance the fluorescence radiation in R6G 44, 45 . This analysis above gives a reasonable explanation to the relationship between the thickness of shells and fluorescence noises observed in experiments.Figure 9Schematic diagram of the surface resonance charge transfer.…”
One of the main challenges for highly sensitive surface-enhanced Raman scattering (SERS) detection is the noise interference of fluorescence signals arising from the analyte molecules. Here we used three types of gold nanostars (GNSs) SERS probes treated by different surface modification methods to reveal the simultaneously existed Raman scattering enhancement and inhibiting fluorescence behaviors during the SERS detection process. As the distance between the metal nanostructures and the analyte molecules can be well controlled by these three surface modification methods, we demonstrated that the fluorescence signals can be either quenched or enhanced during the detection. We found that fluorescence quenching will occur when analyte molecules are closely contacted to the surface of GNSs, leading to a ~100 fold enhancement of the SERS sensitivity. An optimized Raman signal detection limit, as low as the level of 10−11 M, were achieved when Rhodamine 6 G were used as the analyte. The presented fluorescence-free GNSs SERS substrates with plentiful hot spots and controllable surface plasmon resonance wavelengths, fabricated using a cost-effective self-assembling method, can be very competitive candidates for high-sensitive SERS applications.
“…Most previous work on MEF, however, has focused on fluorophores emitting in the visible region, with only a limited number of studies investigating the NIR. 18,20,[25][26][27] Recently, gold (Au) nanocages microprinted into a defined structure with spatial control, allowed fluorescence enhancement in the NIR, but only by a factor of ~2-7. 26 Indeed, most of the recent work for the fluorescent enhancement of NIR dyes has been based on Au or silver (Ag) nanostructures, including nanorods, nanoshells and porous films obtained by dealloying.…”
Section: Introductionmentioning
confidence: 99%
“…18,20,[25][26][27] Recently, gold (Au) nanocages microprinted into a defined structure with spatial control, allowed fluorescence enhancement in the NIR, but only by a factor of ~2-7. 26 Indeed, most of the recent work for the fluorescent enhancement of NIR dyes has been based on Au or silver (Ag) nanostructures, including nanorods, nanoshells and porous films obtained by dealloying. 10,18 For instance, NIR protein microarrays on porous Au films have been employed for multiplexed detection of disease biomarkers.…”
Au nanodisc arrays with nanoscale control of their structural characteristics, allow significant NIR fluorescence enhancement with tunable sensitivities.
“…Silver and gold nanostructures exhibit plasmon absorption in a range from the visible to near infrared and have been widely applied in MEF‐based fluorescent platforms . A variety of metal nanostructures, such as spherical silver nanoparticles, silver nanocubes, spherical gold nanoparticles, gold nanocages, and multi‐branched gold nanoparticles with different plasmon absorptions have been used as magnifying metal nanostructures. Dendritic silver clusters on p‐silicon wafers have been developed by our group, and these structures achieved a 25‐fold enhancement in porphyrin fluorescence intensity .…”
Fluorescent platforms based on organic molecules have attracted great attention in the field of chemical and biological detection because of their high detection efficiency and sensitivity. Strategies in fluorescent platform design with controlled luminescence properties based on Förster resonance energy transfer, excimer/exciplex formation, and metal‐enhanced fluorescence mechanisms are reviewed herein. Attention is focused on the photophysical processes of fluorescent molecules in their interactions with other components as well as with the target. Color‐ and intensity‐tunable luminescence from energy or electron transfer and the electronic structures of fluorescent molecules are discussed. On the basis of the photophysical properties of fluorescent molecules, their responsive fluorescence signals, which reflect specific inter‐ and intra‐molecular interactions, are particularly effective for chemical and biological detection.
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