Fluorophore-induced plasmonic current is generated when an excited fluorophore in close proximity to a metal nanoparticle film nonradiatively transfers energy to the metal, resulting in an electrical ...current across the film. Although a growing literature reports the use of surface plasmons for fluorescence enhancement as well as plasmons for current generation, little has been published hitherto regarding the electrical current generation via the fluorophore excitation of plasmons. Our “plasmon to current” technique utilizes electron transport between closely spaced metal nanoparticles, generating a measurable electrical signal upon excitation of a proximal fluorophore. This induced electrical signal is found to be strongly dependent on the magnitude of the fluorophore extinction coefficient. In other words the electrical signal contains photophysical information pertaining to the fluorophore, potentially leading to the direct detection of fluorescence without the need for traditional detectors such as photomultiplier tubes and charge coupled devices. In addition, we demonstrate the dependence of this current on fluorophore concentration and excitation laser polarization. Fluorophore-induced plasmonic current holds potential as a novel molecular detection platform with simplified instrumentation, compatible with a variety of fluorescent probes.
In this work we investigate the relationship between metal-enhanced fluorescence (MEF) and fluorophore-induced plasmonic current (PC). This is accomplished through measurements of both radiative ...emission (MEF) and direct electrical current generation between discrete metal nanoparticles upon fluorophore excitation (PC). We have conducted these measurements on silver and gold nanoparticle island films, over a range of nanoparticle sizes and spacing in the films. We have observed an inverse relationship in the magnitude of MEF with PC, where larger and more closely spaced metal nanoparticles are found to result in increased PC and subsequently a decreased MEF. We attribute this effect to the relatively high capacitance and low charging energy of large and closely spaced particles, providing an outlet for plasmon relaxation in the form of electron flow and electrical current generation. These results are significant as they open potential for controlling for and the optimization of both MEF and PC.
Significance Coral reefs are highly productive ecosystems that raise a conundrum called “Darwin’s paradox”: How can high production flourish in low-nutrient conditions? We show here that in three ...abundant Caribbean sponges, the granules that have been commonly observed in sponge tissue for decades are polyphosphate granules. These granules can account for up to 40% of the total phosphorus (P) in sponge tissue. This finding has important implications for understanding P sequestration and recycling in the reef environment. We provide evidence that these granules are of bacterial origin and propose a P sequestration pathway by microbial symbionts and the sponge hosts. Considering the ancient origin of both partners, this process may have had an impact on the P cycle in Earth’s early history.
Marine sponges are major habitat-forming organisms in coastal benthic communities and have an ancient origin in evolution history. Here, we report significant accumulation of polyphosphate (polyP) granules in three common sponge species of the Caribbean coral reef. The identity of the polyP granules was confirmed by energy-dispersive spectroscopy (EDS) and by the fluorescence properties of the granules. Microscopy images revealed that a large proportion of microbial cells associated with sponge hosts contained intracellular polyP granules. Cyanobacterial symbionts cultured from sponges were shown to accumulate polyP. We also amplified polyphosphate kinase ( ppk ) genes from sponge DNA and confirmed that the gene was expressed. Based on these findings, we propose here a potentially important phosphorus (P) sequestration pathway through symbiotic microorganisms of marine sponges. Considering the widespread sponge population and abundant microbial cells associated with them, this pathway is likely to have a significant impact on the P cycle in benthic ecosystems.
Three water-soluble fluorescent probes have been specifically designed to determine free cyanide concentrations up to physiologically lethal levels, >20 μM. The probes have been designed in such a ...way as to afford many notable sensing features, which render them unique with regard to signal transduction, photophysical characteristics, and their application to physiological cyanide determination and safeguard. The probes are readily able to reversibly bind free aqueous cyanide with dissociation constants around 4 μM3. Subsequent cyanide binding modulates the intramolecular charge transfer within the probes, a change in the electronic properties within the probes, resulting in enhanced fluorescence optical signals as a function of increased solution cyanide concentration. The ground-state chelation with cyanide produces wavelength shifts, which also enable the probes to sense cyanide in both an excitation and emission ratiometric manner, in addition to enhanced fluorescence signaling. This has enabled a generic cyanide sensing platform to be realized that is not dependent on fluorescent probe concentration, probe photodegradation, or fluctuations in the intensity of any employed excitation sources, ideal for remote cyanide sensing applications. Further, the >600 nm fluorescence emission of the probes potentially allows for enhanced fluorescence ratiometric cyanide sensing in the optical window of tissues and blood, facilitating their use for the transdermal monitoring of cyanide for mammalian safeguard or postmortem in fire victims, both areas of active research.
Chemiluminescent-based detection is entrenched throughout the biosciences today, such as in blotting, analyte and protein quantification and detection. While the biological applications of ...chemiluminescence are forever growing, the underlying principles of using a probe, an oxidizer and a catalyst (biological, organic or inorganic) have remained mostly unchanged for decades. Subsequently, chemiluminescence-based detection is fundamentally limited by the classical photochemical properties of reaction yield, quantum yield, etc. However, over the last 5 years, a new technology has emerged which looks set to fundamentally change the way we both think about and use chemiluminescence today. Metal surface plasmons can amplify chemiluminescence signatures, while low-power microwaves can complete reactions within seconds. In addition, thin metal films can convert spatially isotopic chemiluminescence into directional emission. In this forward looking tutorial review, we survey what could well be the next-generation chemiluminescent-based technologies.
In this paper, we demonstrate fluorophore-induced plasmonic current (FIPC) from aluminum nanoparticle films. It has been previously shown that near-field excited fluorophores are able to ...plasmonically couple with metal nanoparticle films (MNFs) and induce surface plasmons, which in turn leads to a direct measurable electrical current through the MNF. These currents have been detected and quantified in noble metal MNFs; however, due to future envisioned cost considerations, there has been a push to adapt FIPC for use with less expensive metals. Subsequently, we observe that plasmonic aluminum films are able to produce these current changes when in close proximity to excited fluorophores, and the magnitude of the current changes is in accord with to the magnitude of the extinction coefficients of the fluorophores themselves. These findings also further support recent literature reports showing the inverse relationship between metal-enhanced fluorescence and FIPC.
Over the past 15 years, fluorescence has become the dominant detection/sensing technology in medical diagnostics and biotechnology. Although fluorescence is a highly sensitive technique, where single ...molecules can readily be detected, there is still a drive for reduced detection limits. The detection of a fluorophore is usually limited by its quantum yield, autofluorescence of the samples and/or the photostability of the fluorophores; however, there has been a recent explosion in the use of metallic nanostructures to favorably modify the spectral properties of fluorophores and to alleviate some of these fluorophore photophysical constraints. The use of fluorophore–metal interactions has been termed radiative decay engineering, metal-enhanced fluorescence or surface-enhanced fluorescence.
Brominated carbon nanodots are a new carbon nanostructure that exhibits strong phosphorescence without fixation. Herein we report plasmonic amplification of this phosphorescence in silver-coated ...Quanta Plate™ wells, a technique called metal-enhanced phosphorescence (MEP). Subsequently we correlate the excitation and emission components of brominated carbon nanodots to their respective enhancement values. These properties are then discussed in relation to the synchronous scattering spectrum of the plasmonic substrate, in the first report of its kind for MEP. These results set the foundation for expanded application of carbon nanodots, as the photophysical characteristics of phosphorescence are improved, and augment the growing understanding of MEP.
Rapid sample preparation is one of the leading bottlenecks to low-cost and efficient sample component detection. To overcome this setback, a technology known as Lyse-It has been developed to rapidly ...(less than 60 seconds) lyse Gram-positive and-negative bacteria alike, while simultaneously fragmenting DNA/RNA and proteins into tunable sizes. This technology has been used with a variety of organisms, but the underlying mechanism behind how the technology actually works to fragment DNA/RNA and proteins has hitherto been studied. It is generally understood how temperature affects cellular lysing, but for DNA/RNA and protein degradation, the temperature and amount of energy introduced by microwave irradiation of the sample, cannot explain the degradation of the biomolecules to the extent that was being observed. Thus, an investigation into the microwave generation of reactive oxygen species, in particular singlet oxygen, hydroxyl radicals, and superoxide anion radicals, was undertaken. Herein, we probe one aspect, the generation of reactive oxygen species (ROS), which is thought to contribute to a non-thermal mechanism behind biomolecule fragmentation with the Lyse-It technology. By utilizing off/on (Photoinduced electron transfer) PET fluorescent-based probes highly specific for reactive oxygen species, it was found that as oxygen concentration in the sample and/or microwave irradiation power increases, more reactive oxygen species are generated and ultimately, more oxidation and biomolecule fragmentation occurs within the microwave cavity.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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