Antibiotic resistance development in bacteria is an ever-increasing global health concern as new resistant strains and/or resistance mechanisms emerge each day, out-pacing the discovery of novel ...antibiotics. Increasingly, research focuses on alternate techniques, such as antimicrobial photodynamic therapy (APDT) or photocatalytic disinfection, to combat pathogens even before infection occurs. Small molecule "photosensitizers" have been developed to date for this application, using light energy to inflict damage and death on nearby pathogens via the generation of reactive oxygen species (ROS). These molecular agents are frequently limited in widespread application by synthetic expense and complexity. Carbon dots, or fluorescent, quasi-spherical nanoparticle structures, provide an inexpensive and "green" solution for a new class of APDT photosensitizers. To date, reviews have examined the overall antimicrobial properties of carbon dot structures. Herein we provide a focused review on the recent progress for carbon nanodots in photodynamic disinfection, highlighting select studies of carbon dots as intrinsic photosensitizers, structural tuning strategies for optimization, and their use in hybrid disinfection systems and materials. Limitations and challenges are also discussed, and contemporary experimental strategies presented. This review provides a focused foundation for which APDT using carbon dots may be expanded in future research, ultimately on a global scale.
Metal-enhanced fluorescence Geddes, Chris D
Physical chemistry chemical physics : PCCP,
12/2013, Letnik:
15, Številka:
45
Journal Article
Recenzirano
Metal-Enhanced Fluorescence is changing the way we think about and use traditional far-field fluorescence spectroscopy, this special issue discusses the latest trends in this rapidly emerging ...discipline.
Sample preparation is an essential step for nearly every type of biochemical analysis in use today. Among the most important of these analyses is the diagnosis of diseases, since their treatment may ...rely greatly on time and, in the case of infectious diseases, containing their spread within a population to prevent outbreaks. To address this, many different methods have been developed for use in the wide variety of settings for which they are needed. In this work, we have reviewed the literature and report on a broad range of methods that have been developed in recent years and their applications to point-of-care (POC), high-throughput screening, and low-resource and traditional clinical settings for diagnosis, including some of those that were developed in response to the coronavirus disease 2019 (COVID-19) pandemic. In addition to covering alternative approaches and improvements to traditional sample preparation techniques such as extractions and separations, techniques that have been developed with focuses on integration with smart devices, laboratory automation, and biosensors are also discussed.
The benefits of metal-enhanced fluorescence versus traditional fluorescence are many, including increased efficiency of fluorescence emission and increased detection sensitivity. Summarizing the ...current progress in the field through a variety of authoritative reviews, Metal-Enhanced Fluorescence provides a comprehensive collection of current trends, thoughts, and emerging hot aspects in the field of metal-fluorophore interactions and applications. Written by a leader in the field, this in-depth guide introduces graduate...
Surface plasmons are collective oscillations of free electrons at metallic surfaces. These oscillations can give rise to the intense colors of solutions of plasmon resonance nanoparticles and/or very ...intense scattering. While the use of plasmonic particle absorption based bioaffinity sensing is now widespread throughout biological research, the use of their scattering properties is relatively ill explored. We refer to the use, utility and control of surface plasmons as
plasmonics. In this review and forward-looking article, we discuss the current opinions and uses of plasmonics, as well as speculate on areas of future research. These include the use of plasmon scatter for long-range immunosensing and macromolecular conformation studies, as well as the ability to Stokes shift plasmon scatter, a plasmonics phenomenon recently referred to as metal-enhanced fluorescence.
While the utility of reactive oxygen species in photodynamic therapies for both cancer treatments and antimicrobial applications has received much attention, the inherent potential of reactive ...nitrogen species (RNS) including nitric oxide (NO&z.rad;) for these applications should not be overlooked. In recent years, NO&z.rad; donor species with numerous-including photodynamic-mechanisms have been classified with efficacy in antimicrobial and therapeutic applications. While properties of NO&z.rad; delivery may be tuned structurally, herein we describe for the first time a method by which photodynamic NO&z.rad; release is amplified simply by utilizing a plasmonic metal substrate. This is a process we term "metal-enhanced nitric oxide release", or ME-NO&z.rad;. Using donor agents known as brominated carbon nanodots (BrCND), also the first carbon nanodot variation classified to release NO&z.rad; photodynamically, and the
fluorescence-on
probe DAF-FM, we report metal-enhanced release of NO&z.rad; 2- to 6-fold higher than what is achieved under classical conditions. Factors affecting the plasmon-amplified photodynamic system are subsequently studied, including exposure times, excitation powers, and surface area, and consistent ME-NO&z.rad; factors are reported from BrCND across these tunable conditions. Only probe concentration is determined to impact the detected ME-NO&z.rad; factor, with higher concentrations resulting in improved detectability of "actual" NO&z.rad; release enhancement. Further, principles of metal-enhanced fluorescence (MEF) are applied to achieve a faster, high-throughput experimental method with improved data resolution in ME-NO&z.rad; detection. The results have significant implications for the improvement of not just carbon nanodot NO&z.rad; donor agents, but a wide spectrum of photoactivated NO&z.rad; donor systems as well.
Nitric oxide (NO&z.rad;) photo-release from brominated carbon nanodots (BrCND) displays also metal-enhancement (ME-NO&z.rad;)
via
inter-plasmon-donor effects.
Many diagnostic fluorescence assays are limited by sensitivity (signal/noise) and minimum sample volume requirements. Herein we report a new, silvered conical-bottom 96-well plate platform used to ...increase the detectability from very small volumes of micromolar concentrations of fluorophores. This technology employs the principles of metal-enhanced fluorescence (MEF), which is the process by which fluorescence emission is amplified in the near-field of plasmonic nanoparticles. By combining the MEF effect with the advantages of a small volume conical well, we report and characterize detectable emission from fluorescent solutions down to 3 microliters in volume. We report enhancement factors for fluorescein and Rhodamine 6G and correlate these factors to the synchronous scattering spectra of the silvered conical wells. Subsequently, we determine corrected enhancement factors and discuss enhancement in terms of the MEF volume ratio effect and per mole of enhanced fluorophore. The research reported herein sets the foundation for future development of even more powerful MEF-based diagnostic assays.
In a recent paper, our laboratory has shown that fluorophores in close proximity to a non-continuous metal nanoparticle film can induce a detectable electrical current in the film. This current was ...found directly proportional to the fluorophore extinction coefficient and concentration when excited with p-polarized light. This finding threatens to change the way we both think about and use fluorescence spectroscopy as no longer do we have to use and are limited by traditional photodetectors and associated optics to collect and measure fluorescence signatures. This approach holds potential to significantly simplify fluorescence-based instrumentation. In this paper, we significantly expand upon our previous findings and show that plasmonic current is a function of the nanoparticle size and spacing in the film, which is explained by the concentric sphere model for nanoparticle capacitance. We also demonstrate the dependence of plasmonic current on the relative permittivity of the solvent, and that in an excess of salt, the fluorophore-induced current is significantly greater than the background current. This paves the way for downstream plasmonic assays in a variety of biological media. In addition, we have measured plasmonic current as a function of both applied bias voltage and temperature, allowing for the optimization of the fluorophore-induced plasmonic current. These findings allow for not only a better understanding of plasmonic current but also its optimization as it relates to fluorescence-based detection.
We report the development of highly versatile highly fluorescent and photostable core−shell Ag@SiO2 nanocomposites, which allows researchers the flexibility to incorporate just about any fluorophores ...to the outer silica shell by two simple methods. To show the generality of the preparation technique, we have developed three different fluorescent probes: an organic fluorophore (Rh800) and a lanthanide probe doped (noncovalently linked) and an organic fluorophore (Alexa 647) covalently linked to the silica shell. When compared to the control fluorescent nanoparticles (nanobubbles), fluorescent nanoparticles with silver core−silica shell architecture yielded up to 20-fold (with Rh800) enhancement of the fluorescence signal. In terms of nanoparticle detectability for sensing and cellular imaging applications, a 20-fold increase in fluorescence intensity coupled with a 10-fold drop in lifetime affords a total increased detectability of ∼200-fold as compared to the control sample nanobubbles containing the same number of fluorophores. The size, shell thickness, and color of the new MEF-nanoparticles can be easily controlled and optimized for a variety of biological applications, such as cellular entry, imaging, and localization.
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