Search results for "Fluorescence"
showing 10 items of 2463 documents
UV photobleaching of carbon nanodots investigated by in situ optical methods.
2020
Carbon dots are a family of optically-active nanoparticles displaying a combination of useful properties that make them attractive for many applications in photonics and photochemistry. Despite the initial claims of high photostability of carbon dots even under prolonged illuminations, several recent studies have evidenced their photobleaching (PB) under UV light, detrimental for some applications. A study of the mechanism and dynamics of carbon dot PB can be considered a useful route to gather relevant information on the underlying photophysics of these nanoparticles, which is still widely debated. Here we report a study of the PB of carbon dots under UV light, conducted through optical ex…
Chapter 3 Surface Plasmon Optics for the Characterization of Biofunctional Architectures
2007
Publisher Summary This chapter describes a wide variety of work employing surface plasmon resonance (SPR), surface plasmon field-enhanced fluorescence spectroscopy (SPFS), and surface plasmon field-enhanced diffraction spectroscopy (SPDS) analysis, specifically for investigations relevant to biofunctional, bio-affinity aspects. The SPR has shown already its impact on interfacial analysis. The combination of these three methods has the potential to generate more information and reveal details of biofunctional interfaces. The versatility of the SPR technique is shown by a vast amount of publications in the past decades; the method has matured into a well-accepted analytical tool for the chara…
Fluorescence spectroscopy for estimation of anticancer drug sonodestruction in vitro
2013
The effect of ultrasound exposure on bleomycin fluorescence and pharmacological properties is studied. Bleomycin was treated by ultrasound for 7 min. Bleomycin fluorescence was measured during ultrasound exposure by means of fiber-optic spectrometry. Cell colony test was used to evaluate blemycin cytotoxity before and after ultrasound exposure.
Optimizing geometry of low-Q all-metal Fabry-Pérot microcavity for fluorescence spectroscopy
2021
Abstract Fluorescence spectroscopy is commonly employed to study the excited-state photophysics of organic molecules. Planar Fabry-Pérot microcavities play an essential role in such studies and a strategic cavity design is necessary to attain an enhanced light-matter interaction. In this work, we computationally study different geometries for a planar metallic Fabry-Pérot microcavity tuned for the absorption of Sulforhodamine 101, a typical dye for fluorescence spectroscopy. The cavity consists of a polymer layer enclosed between two silver mirrors, where the thicknesses of all the three layers are varied to optimize the cavity. Our transfer-matrix and finite-difference time-domain simulati…
Defined-length Carbon-rich Conjugated Oligomers
2006
Fast whole-brain imaging of seizures in zebrafish larvae by two-photon light-sheet microscopy
2022
Light-sheet fluorescence microscopy (LSFM) enables real-time whole-brain functional imaging in zebrafish larvae. Conventional one photon LSFM can however induce undesirable visual stimulation due to the use of visible excitation light. The use of two-photon (2P) excitation, employing near-infrared invisible light, provides unbiased investigation of neuronal circuit dynamics. However, due to the low efficiency of the 2P absorption process, the imaging speed of this technique is typically limited by the signal-to-noise-ratio. Here, we describe a 2P LSFM setup designed for non-invasive imaging that enables quintuplicating state-of-the-art volumetric acquisition rate of the larval zebrafish bra…
Temperature-Dependence of Solvent-Induced Stokes Shift and Fluorescence Tunability in Carbon Nanodots
2019
We carried out a cryogenic investigation on the optical properties of carbon dots, aiming to better understand their emission mechanism and the role of the solvent. The solvatochromic Stokes shift is quantified by a low temperature approach which allows freezing of the photo-excited state of carbon dots, preventing any solvation relaxation. Moreover, the reduction in temperature helps to identify the dynamical inhomogeneous contribution to the broadening of the emission band; therefore, disentangling the role of solvent from other types of broadening, such as the homogeneous and the static inhomogeneous contributions.
Novel laser technologies for human skin in-vivo assessment
2007
Two experimental methodologies for human skin optical non-invasive in-vivo assessment have been developed and clinically tested - imaging of the laser-excited autofluorescence fading rate, and simultaneous recording of the reflectance photoplethysmography signals at several laser wavelengths with different skin penetration depths. Details of both equipments are described along with some measurement results illustrating feasibility of the novel technologies.
O-Doped Nanographenes: A Pyrano/Pyrylium Route Towards Semiconducting Cationic Mixed-Valence Complexes
2020
Herein we report an efficient synthesis to prepare O‐doped nanographenes, which derive from the longitudinally and latitudinally p‐extension of pyrene. The derivatives are highly fluorescent and feature low‐oxidation potentials. Exploiting electrooxidation, crystals of cationic mixed valence (MV) complexes were grown in which the organic salts organize into face‐to‐face p‐ p stacks, a favorable solid‐state arrangement for organic electronics. Variable‐temperature EPR measurements and relaxation studies suggest a strong electron delocalization along the longitudinal axis of the columnar p‐stacking architectures. Electric measurements of single crystals of the MV salts exhibited a semiconduct…
Nanographenes: Ultrastable, Switchable, and Bright Probes for Super-Resolution Microscopy.
2019
Abstract Super‐resolution fluorescence microscopy has enabled important breakthroughs in biology and materials science. Implementations such as single‐molecule localization microscopy (SMLM) and minimal emission fluxes (MINFLUX) microscopy in the localization mode exploit fluorophores that blink, i.e., switch on and off, stochastically. Here, we introduce nanographenes, namely large polycyclic aromatic hydrocarbons that can also be regarded as atomically precise graphene quantum dots, as a new class of fluorophores for super‐resolution fluorescence microscopy. Nanographenes exhibit outstanding photophysical properties: intrinsic blinking even in air, excellent fluorescence recovery, and sta…