Search results for "photosensitizer"

Understanding and exploiting long-lived near-infrared emission of a molecular ruby

2018

Coordination chemistry reviews 359, 102 - 111 (2018). doi:10.1016/j.ccr.2018.01.004

Photodynamic therapy within edematous brain tissue: Considerations on sensitizer dose and time point of laser irradiation

1996

Photosensitizer is known to spread with vasogenic edema fluid arising from a cerebral lesion (Neurosurg 33:1075-1082, 1993), which may be essential for sensitizing malignant cells outside the main tumor mass. The present experiments seek to elucidate whether resultant necrosis of perifocal brain tissue after laser irradiation follows a corresponding time pattern and whether damage depends on the photosensitizer dose. Male Wistar rats were anaesthetized with chloralhydrate for venous cannulation, craniotomy and focal cold lesion in order to induce vasogenic edema. Simultaneously, Photofrin II (PF II) was administered at a dose of 5 mg kg-1. The animals were re-anaesthetized after either 4, 1…

Kinetics of Photofrin II in perifocal brain edema.

1993

Photodynamic therapy is under intense investigation as a possible adjuvant for the treatment of malignant tumors of the central nervous system. It relies on the fact that photosensitizers are selectively taken up or retained by malignant tissue. However, most brain tumors are accompanied by substantial vasogenic edema as a consequence of blood-brain barrier disruption within the tumor, leading to extravasation and propagation of plasma constituents into the surrounding brain tissue. Systemically administered photosensitizers may enter healthy tissue together with the edema fluid, possibly leading to sensitization of tissues outside the tumor. To test this hypothesis, vasogenic edema was ind…

Highly soluble multifunctional MnO nanoparticles for simultaneous optical and MRI imaging and cancer treatment using photodynamic therapy

2010

Superparamagnetic MnO nanoparticles were functionalized using a hydrophilic ligand containing protoporphyrin IX as photosensitizer. By virtue of their magnetic properties these nanoparticles may serve as contrast enhancing agents for magnetic resonance imaging (MRI), while the fluorescent target ligand protoporphyrin IX allows simultaneous tumor detection and treatment by photodynamic therapy (PDT). Caki-1 cells were incubated with these nanoparticles. Subsequent exposure to UV light lead to cell apoptosis due to photoactivation of the photosensitizer conjugated to the nanoparticles. This method offers great diagnostic potential for highly proliferative tissues, including tumors. In additio…

NIR excitation of upconversion nanohybrids containing a surface grafted Bodipy induces oxygen-mediated cancer cell death

2020

We report the preparation of water-dispersible, ca. 30 nm-sized nanohybrids containing NaYF4:Er3+, Yb3+ up-conversion nanoparticles (UCNPs), capped with a polyethylene glycol (PEG) derivative and highly loaded with a singlet oxygen photosensitizer, specifically a diiodo-substituted Bodipy (IBDP). The photosensitizer, bearing a carboxylic group, was anchored to the UCNP surface and, at the same time, embedded in the PEG capping; the combined action of the UCNP surface and PEG facilitated the loading for an effective energy transfer and, additionally, avoided photosensitizer leaching from the nanohybrid (UCNP-IBDP@PEG). The effectiveness of the nanohybrids in generating singlet oxygen after n…

Copper-mediated DNA photocleavage by a tetrapyridoacridine (tpac) ligand.

2008

Abstract We have focused our interest on the tetrapyridoacridine ligand tetrapyrido[3,2- a :2′,3′- c :3′′,2″- h : 2‴,3‴- j ]acridine (tpac), as a model system for the preparation of novel copper-based artificial nucleases. The complex of copper(II)–tpac cleaves supercoiled pUC18 plasmid DNA in an oxidative manner by photoactivation with visible light, exhibiting maximum cleaving efficiency at 1:2 metal–ligand stoichiometric ratio. We propose an interaction of the copper–tpac complex with DNA through both major and minor grooves and a photocleavage mechanism via the formation of hydroxyl radicals and singlet oxygen or singlet oxygen-like species.

SYNTHESIS OF PYRROLO[3,2-H]QUINOLINONES WITH GOOD PHOTOCHEMOTHERAPEUTIC ACTIVITY AND NO DNA DAMAGE

2010

In the search for new photochemotherapeutic agents, a series of derivatives of the ring system pyrrolo[3,2-h]quinoline--bioisosters of the angular furocoumarin angelicin--were synthesized through a four-step synthetic approach, in reasonable overall yields. Eight of the synthesized derivatives showed a remarkable phototoxicity against a panel of four human tumor cell lines and a great dose UV-A dependence, reaching IC₅₀ values at submicromolar level. The mode of cellular death photoinduced by pyrrolo[3,2-h]quinolines was evaluated through a series of flow cytometric analysis and other tests were performed to clarify their mechanism of action.

An in vitro model to study cellular photosensitizer uptake and photodynamic dose-response relationships of tumor cells

1993

Cellular fluorescence intensity (CFI) after incubation with varying concentrations of the photosensitizer Photofrin and the photodynamically induced dose-response relationships of hamster melanoma cells (A-MEL-3) were studied in a recently developed in vitro model. After administration of Photofrin to the extracellular serum-free medium, CFI was evaluated by flow cytometry together with constantly fluorescing latex particles used as a reference. After 5 min, 50% of maximal CFI was found, and after 60 min CFI was maximal. No further increase was obtained during the exposure to Photofrin over the incubation period of 4 h. During this plateau phase, CFI was significantly related to the concent…

Intramolecular Electron Transfer between Tyrosine and Tryptophan Photosensitized by a Chiral π,π* Aromatic Ketone

2005

The photochemical reaction of Trp and Tyr and related peptides with Suprofen (SUP) as sensitizer in H2O/CH3CN (28:1 v/v) solutions has been studied by time-resolved spectroscopy. The results show that SUP induces oxidation of both Trp and Tyr, as well as intramolecular-ET reactions in the related peptides. The influence of photosensitizer configuration on the involved processes has been studied by using the enantiomerically pure compounds. A significant chiral recognition is observed in which the concentration of the radicals formed after triplet quenching depends on the configuration of the chiral center; the quenching process is higher when using the (R)-SUP enantiomer.

2019

In photodynamic therapy (PDT), photosensitizers and light are used to cause photochemically induced cell death. The selectivity and the effectiveness of the phototoxicity in cancer can be increased by a specific uptake of the photosensitizer into tumor cells. A promising target for this goal is the folic acid receptor α (FRα), which is overexpressed on the surface of many tumor cells and mediates an endocytotic uptake. Here, we describe a polysaccharide-based nanoparticle system suitable for targeted uptake and its photochemical and photobiological characterization. The photosensitizer 5, 10, 15, 20-tetraphenyl-21H, 23H-porphyrine (TPP) was encapsulated in spermine- and acetal-modified dext…