time-resolved phosphorescence
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Recently, we reported induced anoxia as a limiting factor for photodynamic tumor therapy (PDT). This effect occurs in vivo if the amount of generated singlet oxygen that undergoes chemical reactions with cellular components exceeds the local oxygen supply. The amount of generated singlet oxygen depends mainly on photosensitizer (PS) accumulation, efficiency, and illumination intensity. With illumination intensities above a certain threshold, singlet oxygen is limited to the blood vessel and the nearest vicinity; lower intensities allow singlet oxygen generation also in tissue which is a few cell layers away from the vessels. While all experiments so far were limited to light intensities above this threshold, we report experimental results for intensities at both sides of the threshold for the first time, giving proof for the described model. Using time-resolved optical detection in NIR, we demonstrate characteristic, illumination intensity-dependent changes in signal kinetics of singlet oxygen and photosensitizer phosphorescence in vivo. The described analysis allows for better optimization and coordination of PDT drugs and treatment, as well as new diagnostic methods based on gated PS phosphorescence, for which we report a first in vivo feasibility test.
- Publikační typ
- časopisecké články MeSH
The presented work addresses the influence of illumination intensity on the amount and locations of singlet oxygen generation in tumor tissue. We used time-resolved optical detection at the typical emission wavelength around 1270 nm and at 1200 nm where there is no singlet oxygen phosphorescence to determine the phosphorescence kinetics. The discussed data comprise in vivo measurements in tumor-laden HET-CAM and mice. The results show that illumination that is too intense is a major issue, affecting many PDT treatments and all singlet oxygen measurements in vivo so far. In such cases, photosensitization and oxygen consumption exceed oxygen supply, limiting singlet oxygen generation to the blood vessels and walls, while photosensitizers in the surrounding tissue will likely not participate. Being a limitation for the treatment, on one hand, on the other, this finding offers a new method for tumor diagnosis when using photosensitizers exploiting the EPR effect. In contrast to high-intensity PDT, some papers reported successful treatment with nanoparticular drugs using much lower illumination intensity. The question of whether, with such illumination, singlet oxygen is indeed generated in areas apart from vessels and walls, is addressed by numerical analysis. In addition, we discuss how to perform measurements at such low intensities.
- Publikační typ
- časopisecké články MeSH
A highly prospective drug for the X-ray induced photodynamic therapy (PDTX), LuAG:Pr3+@SiO2-PpIX nanocomposite, was successfully prepared by a three step process: photo-induced precipitation of the Lu3Al5O12:Pr3+(LuAG:Pr3+) core, sol-gel technique for amorphous silica coating, and a biofunctionalization by attaching the protoporphyrin IX (PpIX) molecules. The synthesis procedure provides three-layer nanocomposite with uniform shells covering an intensely luminescent core. Room temperature radioluminescence (RT RL) spectra as well as photoluminescence (RT PL) steady-state and time resolved spectra of the material confirm the non-radiative energy transfer from the core Pr3+ions to the PpIX outer layer. First, excitation of Pr3+ions results in the red luminescence of PpIX. Second, the decay measurements exhibit clear evidence of mentioned non-radiative energy transfer (ET). The singlet oxygen generation in the system was demonstrated by the 3'-(p-aminophenyl) fluorescein (APF) chemical probe sensitive to the singlet oxygen presence. The RT PL spectra of an X-ray irradiated material with the APF probe manifest the formation of singlet oxygen due to which enhanced luminescence around 530 nm is observed. Quenching studies, using NaN3as an1O2inhibitor, also confirm the presence of1O2in the system and rule out the parasitic reaction with OH radicals. To summarize, presented features of LuAG:Pr3+@SiO2-PpIX nanocomposite indicate its considerable potential for PDTX application.
Singlet oxygen is a highly reactive species which is involved in a number of processes, including photodynamic therapy of cancer. Its very weak near-infrared emission makes imaging of singlet oxygen in biological systems a long-term challenge. We address this challenge by introducing Singlet Oxygen Feedback Delayed Fluorescence (SOFDF) as a novel modality for semi-direct microscopic time-resolved wide-field imaging of singlet oxygen in biological systems. SOFDF has been investigated in individual fibroblast cells incubated with a well-known photosensitizer aluminium phthalocyanine tetrasulfonate. The SOFDF emission from the cells is several orders of magnitude stronger and much more readily detectable than the very weak near-infrared phosphorescence of singlet oxygen. Moreover, the analysis of SOFDF kinetics enables us to estimate the lifetimes of the involved excited states. Real-time SOFDF images with micrometer spatial resolution and submicrosecond temporal-resolution have been recorded. Interestingly, a steep decrease in the SOFDF intensity after the photodynamically induced release of a photosensitizer from lysosomes has been demonstrated. This effect could be potentially employed as a valuable diagnostic tool for monitoring and dosimetry in photodynamic therapy.
- MeSH
- buňky 3T3 MeSH
- časové faktory MeSH
- fibroblasty chemie cytologie MeSH
- fluorescence * MeSH
- fluorescenční mikroskopie MeSH
- fotochemoterapie MeSH
- fotosenzibilizující látky chemie MeSH
- indoly chemie MeSH
- kultivované buňky MeSH
- myši MeSH
- optické zobrazování * MeSH
- organokovové sloučeniny chemie MeSH
- singletový kyslík analýza chemie MeSH
- viabilita buněk MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Edukační publikace se zabývá v první části luminiscenčními metodami: luminiscencí lanthanidů rozloženou v čase, luminiscencí lanthanidů zesílenou enzymem, homogenní imunoanalýzou s pohlcením luminiscence, chemiluminiscencí, elektrochemiluminiscencí (kompetitivní i sendvičové uspořádání a metoda přímé interakce) a možnostmi simultánních imunoanalýz s elektrochemiluminiscenční detekcí. Druhá část je věnována imunoanalýzám s elektrochemickou detekcí, zejména anodickou rozpouštěcí voltametrií a square-wave voltametrií. Jako značky se používají různé nanomateriály: zlato, stříbro, polovodiče (CdS, PbS, ZnS, CuS), uhlíkové nanotrubičky (plněné enzymem), apoferitin (plněný ferokyanidem nebo ionty Cd 2+ nebo Pb 2+ ), liposomy (plněné ferokyanidem), křemenné částice (s kovalentně vázaným polyguaninem, nebo plněné peroxidázou a thioninem), mikrokrystaly ferrocenu a jiné.
The first part of the educational article deals with luminescence methods as follows: lanthanide-based time-resolved luminescence, enzyme-amplified lanthanide luminescence, homogeneous immunoassays with luminescence quenching, chemiluminescence, electrochemiluminescence (competitive assay, sandwich-type assay, and direct interaction) and simultaneous immunoassays options with electrochemical luminescence detection. The second part covers immunoassays with electrochemical detection, particularly anodic stripping voltammetry and square-wave voltammetry. Many kinds of nanomaterials are used as labels, e.g. gold, silver, semiconductors (CdS, PbS, ZnS, CuS), carbon nanotubes (enzyme-loaded), apoferritin (hexacyanoferrate loaded, in some cases Cd 2+ or Pb 2+ ions are used), liposomes (hexacyanoferrate loaded), silica particles (by covalently binding polyguanine or with peroxidase & thionine loaded), ferrocene microcrystals, etc. Keywords: Lanthanide-based luminescence, chemiluminescence, electrochemiluminescence, electrochemical immunoassays, nanomaterials.
... Siebert -- Lecture at the Invitation of the European Committee -- The Combination of Time-Resolved Step-Scan ... ... Bryant -- Function of Enzymes and Other Active Proteins III (Enzyme Function III) -- 11:00-12:45 -- Time-Resolved ... ... Structural Dynamics of Proteins (Protein Folding) -- 9:00-10:45 vi9\" ECSBM -- Table of Contents -- Time-Resolved ... ... Naumann -- Room-Temperature Phosphorescence of Native and Inactivated Actin 64 -- V. M. Mazhul. E. ... ... -M. ruysschaert and E. goormachtich -- Time-Resolved Step-Scan FTIR Investigations of the Photophobie ...
2 sv. (150 s., s. 151-274) : il., tab. ; 25 cm
