Search results for "photosensitizer"
showing 10 items of 44 documents
Acridine orange in a pumpkin-shaped macrocycle: Beyond solvent effects in the UV–visible spectra simulation of dyes
2010
Abstract We present simulation of the UV–visible spectra of acridine orange, a widely used photosensitizer for in vivo studies due to its highly environment-dependent spectroscopic properties. This dye has been investigated both in its protonated and neutral forms, either isolated or embedded in a pumpkin-shaped macromolecular cycle (cucurbit-7-uril), using time-dependent density functional theory techniques. To model this macromolecular cycle, two strategies are taken into account, allowing decoupling of the geometric and electrostatic influences of the host on the guest molecules. Experimental data are well-reproduced when using an embedding electrostatic technique, suggesting that such a…
Nanohybrid for Photodynamic Therapy and Fluorescence Imaging Tracking without Therapy
2018
Theranostic upconversion nanoparticles (UCNPs) are ideal candidates for personalized medicine. We present a smart, easy-to-prepare nanohybrid (NH) suitable for NIR-theragnosis and imaging tracking without triggering therapy simultaneously. The photophysical features of each component have been carefully selected in order to maximize the capabilities for theragnosis, in particular, the upconversion emission and the photosensitizer absorption. In addition, NH presents a fluorescent marker with one-photon absorption in the green and two-photon absorption cross-section at NIR wavelengths where the UCNP does not absorb, thus enabling innocuous tracking. Thus, the NH consists of NaYF4:Yb, Er, Tm …
Oxidative DNA base damage induced by singlet oxygen and photosensitization: recognition by repair endonucleases and mutagenicity.
2000
We have analyzed the recognition by various repair endonucleases of DNA base modifications induced by three oxidants, viz. [4-(tert-butyldioxycarbonyl)benzyl]triethylammonium chloride (BCBT), a photochemical source of tert-butoxyl radicals, disodium salt of 1,4-etheno-2,3-benzodioxin-1,4-dipropanoic acid (NDPO(2)), a chemical source of singlet oxygen, and riboflavin, a type-I photosensitizer. The base modifications induced by BCBT, which were previously shown to be mostly 7,8-dihydro-8-oxoguanine (8-oxoGua) residues, were recognized by Fpg and Ogg1 proteins, but not by endonuclease IIII, Ntg1 and Ntg2 proteins. In the case of singlet oxygen induced damage, 8-oxoGua accounted for only 35% of…
Study of the Mode and Efficiency of DNA Binding in the Damage Induced by Photoactivated Water Soluble Porphyrins
2013
We have investigated the DNA binding interactions and in vitro photoactivated DNA damage induced by a neutral water soluble porphyrin derivative 5,10,15,20-tetrakis(2,4,6-trihydroxyphenyl)porphyrin (TTHPP) and its zinc derivative 5,10,15,20-tetrakis(2,4,6-trihydroxyphenyl)porphyrinato zinc(II) (Zn-TTHPP) upon visible light irradiation through various spectroscopic techniques and employing repair endonucleases. These porphyrin derivatives exhibited high affinity toward DNA through groove binding interactions as evidenced through the UV-vis absorption, emission, circular dichroism spectral and viscosity changes. Interestingly, the free base porphyrin derivative, TTHPP generated efficient sing…
Enhanced effects of aminolaevulinic acid-based photodynamic therapy through local hyperthermia in rat tumours.
2003
The possibility of enhancing aminolaevulinic acid (ALA)-based photodynamic therapy (PDT) by simultaneous application of localised hyperthermia (HT) was evaluated. Treatments of rat DS-sarcomas included: (i) control, (ii) ALA administration (375 mg kg(-1), i.p.), no illumination, (iii) 'nonthermal' illumination, (iv) ALA-PDT: that is, ALA administration, 'nonthermal' illumination, (v) localised HT, 43 degrees C, 60 min (vi) ALA-PDT+HT: ALA administration with full spectrum irradiation resulting in ALA-PDT and HT. Tumour volume was monitored for 90 days or until a target volume (3.5 ml) was reached. No differences were seen between the first three groups, with all tumours reaching the target …
SYNTHESIS AND PHOTOCHEMIOTHERAPEUTIC ACTIVITY OF THIOPYRANO[2,3-E]INDOL-2-ONES
2004
A series of derivatives of the new ring system thiopyrano[2,3-e]indol-2-one was prepared with the aim of obtaining new photochemotherapeutic drugs. Biological screenings were performed on this new class of photoactivable drugs and a strong antiproliferative effect was observed upon irradiation with UVA light. The compound bearing a methyl substituent at the pyrrole nitrogen resulted as the most interesting showing IC50 in the nanomolar range.
THIOPYRANO[2,3-E]INDOL-2-ONES: ANGELICIN HETEROANALOGUES WITH POTENT PHOTOANTIPROLIFERATIVE ACTIVITY
2008
A new class of compounds, the thiopyrano[2,3-e]indol-2-ones, bioisosters of the angular furocoumarin angelicin, was synthesized with the aim of obtaining new photochemotherapeutic agents. In particular 7,8-dimethyl-thiopyranoindolone 6c s showed a remarkable phototoxicity and a great dose UVA dependence reaching IC(50) values at submicromolar level. This latter photoinduced a massive apoptosis and a remarkable photodamage to lipids and proteins. Although it did not intercalate DNA, it was able to cause photooxidation of DNA bases.
Double stimuli-responsive polysaccharide block copolymers as green macrosurfactants for near-infrared photodynamic therapy
2019
The NIR absorbing photosensitizer phthalocyanine zinc (PC(Zn)) was stabilized in aqueous media as water-dispersible nanoparticles with a reduction- and pH-responsive full polysaccharide block copolymer. A cellular uptake and also photo switchable intracellular activity of the cargo upon irradiation at wavelengths in the near infrared region were shown. The block copolymer was synthesized by applying a copper-free click strategy based on a thiol exchange reaction, creating an amphiphilic double-stimuli-responsive mixed disulfide. The dual-sensitive polysaccharide micelles represent a non-toxic and biodegradable green macrosurfactant for the delivery of phthalocyanine zinc. By encapsulation i…
The family of furocoumarins: Looking for the best photosensitizer for phototherapy
2008
Abstract Furocoumarins are widely used as photosensitizers in photochemical therapies against different skin disorders such as psoriasis and vitiligo. Absorption of near-UV light by the chromophore triggers a set of photoreactions related to the therapeutic properties of the technique: linkage of a furocoumarin to thymine DNA nucleobases preventing proliferation of pathogenic cells, or generation of highly reactive singlet oxygen in damaged tissues. The family of furocoumarins has been studied in depth for many years seeking a drug having the most remarkable set of properties to act as a photosensitizer. For this purpose, understanding the underlying photochemical mechanisms behind the effe…