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Monitoring plasmonic hot-carrier chemical reactions at the single particle level
摘要： Plasmon excitation in metal nanoparticles triggers the generation of highly energetic charge carriers that - properly manipulated and exploited - can mediate chemical reactions. Single-particle techniques are key to unearth the underlying mechanisms of hot-carrier generation, transport and injection as well as to disentangle the role of the temperature increase and the enhanced near-field at the nanoparticle-molecule interface. Gaining a nanoscopic insight of these processes and their interplay could aid in the rational design of plasmonic photocatalysts. Here, we present three different approaches to monitor hot-carrier reactivity at the single-particle level. We use a combination of dark-field microscopy and photo-electrochemistry to track a hot-hole driven reaction on a single Au nanoparticle. We image hot-electron reactivity with sub-particle spatial resolution using nanoscopy techniques. Finally, we push the limits looking for a hot-electron induced chemical reaction that generates a fluorescent product, which should enable imaging of active plasmonic photocatalysis at the single-particle and single-molecule levels.
关键词： dark-field microscopy,fluorescent product,single-particle techniques,Plasmonic hot-carriers,plasmonic photocatalysis,photo-electrochemistry,nanoscopy techniques
更新于2025-11-19 16:56:42
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Photon Counting - Fundamentals and Applications || Detectors for Super-Resolution & Single-Molecule Fluorescence Microscopies
摘要： The resolution of light microscopy was thought to be limited to 250–300 nanometers based on the work of Ernest Abbe. This Abbe diffraction limit was believed to be insurmountable until the invention of Super-resolution microscopic techniques in the late 20th century. These techniques remove this limit and have provided unprecedented detail of cellular structures and dynamics down to several nanometers. An emerging goal in this field is to quantitatively measure individual molecules. Measurement of single-molecule dynamics, such as diffusion coefficients and complex stoichiometries, can be accomplished using fluorescence fluctuation techniques to reveal nanosecond-to-microsecond temporal reactions. These powerful complimentary experimental approaches are made possible by sensitive low-light photodetectors. In this chapter, an overview of the principles of super-resolution and single-molecule microscopies are provided. The different types of photodetectors employed in these techniques are explained. In addition, the advantages and disadvantages for these detectors are discussed, as well as the development of next generation detectors. Finally, example super-resolution and single-molecule cellular studies that take advantage of these detector technologies are presented.
关键词： biophysical techniques,STORM,nanoscopy,STED,protein dynamics,palm,spectroscopy,molecular brightness,fluorescence fluctuation
更新于2025-09-23 15:23:52
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Fluorescence Imaging for Ultrafiltration of Individual Nanoparticles from a Colloidal Solution in Track Membranes
摘要： We have used ? uorescence nanoscopy for direct imaging of adsorption of individual colloidal quantum dots of diameter ~10 nm (spherical core/shell CdSeS/ZnS semiconductor nanocrystals, functionalized by organic oleic acid ligands) in nanopores of a nuclear ? lter (a polypropylene track membrane with pores of diameter ~500 nm). We have shown that when a colloidal toluene solution passes through the pores of the membrane, the nanoparticles are completely retained at a depth of 10 μm.
关键词： nanopore,single-photon source,CdSe,membrane,nanoscopy,entangled-photon source,quantum dot,colloidal solution,microscopy,nanoparticles,ultra? ltration,oleic acid,nuclear ? lter,luminescence,polymer
更新于2025-09-23 15:21:21
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Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles
摘要： Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum-resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo (M3C) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets.
关键词： ethanol,water,SiO2 nanoparticles,photocatalysts,nanoparticles,Mie Monte-Carlo calculations,momentum-resolved photoionization,reaction nanoscopy,near-fields
更新于2025-09-19 17:13:59
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Pump-Probe Nanoscopy by Means of Transient Absorption Saturation
摘要： In this paper, we present a method to perform super-resolution label-free optical microscopy by means of the saturation of the transient absorption process. We developed a novel and easy-to-implement setup based on a commercial confocal microscope. We demonstrate the imaging capability by looking at single layer graphene (SLG) deposited on a glass surface via chemical vapour deposition (CVD). Exploiting near-infrared femtosecond pulsed laser beams and saturation of the transient absorption, we can reach a resolution below λ/10 nm.
关键词： absorption saturation,nanoscopy,NIR,pump-probe,STED,graphene
更新于2025-09-10 09:29:36
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Nanoscale Imaging of Kidney Glomeruli Using Expansion Pathology
摘要： Kidney glomerular diseases, such as the minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS), and other nephrotic syndromes, are typically diagnosed or confirmed via electron microscopy. Although optical microscopy has been a vital tool to examine clinical specimens for diagnoses in pathology for decades, the optical resolution is constricted by the physical diffraction limit of the optical microscope, which prevents high-resolution investigation of subcellular anatomy, such as of the podocyte tertiary foot processes. Here, we describe a simple, fast, and inexpensive protocol for nanoscale optical imaging of kidney glomeruli. The protocol is based on Expansion Pathology (ExPath), a new principle of microscopy that overcomes optical diffraction limit by chemically embedding specimens into a swellable polymer and physically expanding it homogenously prior to imaging. Our method uses only commercially available reagents, a conventional fluorescence microscope and it can be applied to both fixed-frozen or formalin-fixed paraffin embedded (FFPE) tissue sections. It requires minimal operative experience in a wet lab, optical microscopy and imaging processing. Finally, we also discuss challenges, limitations and prospective applications for ExPath-based imaging of glomeruli.
关键词： imaging,kidney glomerulus,immunostaining,expansion microscopy,tissue expansion,nanoscopy
更新于2025-09-09 09:28:46
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Triarylmethane Fluorophores Resistant to Oxidative Photobluing
摘要： Spectral stability of small-molecule fluorescent probes is required for correct interpretation and reproducibility of multicolor fluorescence imaging data, in particular under high (de)excitation light intensities of super-resolution imaging or in single-molecule applications. We propose a synthetic approach to a series of spectrally stable rhodamine fluorophores based on sequential Ru- and Cu-catalyzed transformations, evaluate their stability against photobleaching and photoconversion in context of other fluorophores using chemometric analysis, and demonstrate chemical reactivity of fluorophore photoproducts. The substitution patterns providing the photoconversion-resistant triarylmethane fluorophores have been identified, and the applicability of non-bluing labels in live-cell STED nanoscopy is demonstrated.
关键词： STED nanoscopy,photostability,triarylmethane fluorophores,rhodamine fluorophores,oxidative photobluing
更新于2025-09-04 15:30:14