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Jessica van Wonderen, Daobo Li, Samuel Piper, Cheuk Lau, Leon Piper, Christopher Hall, Thomas Clarke, Nicholas Watmough, Julea N Butt
Multiheme cytochromes possess closely packed redox-active hemes arranged as chains spanning the tertiary structure. Here we describe five variants of a representative multiheme cytochrome engineered as biohybrid phototransducers converting light to electricity. Each variant possesses a single Cys-sulfhydryl near a terminus of the heme chain and that was efficiently labelled with a Ru(II)(bipyridine)3 photosensitiser. When irradiated in the presence of a sacrificial electron donor the proteins exhibited different behaviours...
July 18, 2018: Chembiochem: a European Journal of Chemical Biology
Steven Y Yap, Thomas W Price, Huguette Savoie, Ross W Boyle, Graeme J Stasiuk
A theranostic conjugate for use as a positron emission tomography (PET) radiotracer and as a photosensitiser for photodynamic therapy (PDT) has been synthesised. A water-soluble porphyrin was coupled with the bifunctional chelate, This conjugate is capable of rapid 68Ga complexation under physiological conditions; with 93% and 80% radiochemical yields achieved, at pH 4.5 and pH 7.4 respectively, in 15 min at 25 °C. Photocytotoxicity was evaluated on HT-29 cells and showed the conjugate was capable of >50% cell death at 50 μM upon irradiation with light, while causing minimal toxicity in the absence of light (>95% cell survival)...
June 29, 2018: Chemical Communications: Chem Comm
Ashka Amina, Deepali V Kaduskar
AIMS AND BACKGROUND: Number of pathogenic microorganisms have been increasing over the years, and so as these microorganisms been developing resistance against various antibiotics. Antimicrobial photodynamic therapy (aPDT), also called photodynamic inactivation, is emerging as a promising alternative to treatments based on conventional antibiotics. Recent patents on structured silver mesoporous silica nanoparticles having antimicrobial activity (WO2010/071831 A2), photosensitiser modified core-shell structure nanocomposites (CN 103536935(A)), and Chitosan-coated magnetic mesoporous silica nanoparticles (CN 104785214(A)) helped in selecting method of synthesis of MSN and photosensitizers...
June 26, 2018: Recent Patents on Drug Delivery & Formulation
Roberto Zagami, Giuseppe Sortino, Enrico Caruso, Miryam Malacarne, Stefano Banfi, Salvatore Patanè, Luigi Monsu Scolaro, Antonino Mazzaglia
Amphiphilic cyclodextrins (aCD) are an intriguing class of carrier systems which, recently, have been proposed to deliver porphyrinoids and anticancer drugs or combined dose of both for dual therapeutic applications. The design of nanoassemblies based on aCD and photosensitisers (PSs) aims to preserve the PDT efficacy of PS, reducing the tendency of PS to self-aggregate, without affecting the quantum yield of singlet oxygen (1O2) production, and, not less importantly, minimizing dark toxicity and reducing photosensitization effects...
June 25, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Li Wencheng, Kichul Cho, Yasuhiro Yamasaki, Satoshi Takeshita, Kiju Hwang, Daekyung Kim, Tatsuya Oda
The dinoflagellate Heterocapsa circularisquama is highly toxic to bivalves. However, significant toxicity to finfish species has not been reported. We previously found that H. circularisquama has light-dependent haemolytic agents. Purification and chemical structural analyses revealed that the haemolytic agent H2-a is a porphyrin derivative, which exhibits light-dependent cytotoxicity toward tumour cells. To clarify the biological activity of H2-a further, its antibacterial activities against Gram-positive and Gram-negative bacteria were investigated in this study...
June 7, 2018: Aquatic Toxicology
Mark Wainwright
The search for suitable, low-molecular weight photoantimicrobials for use in infection control has strong foundations in conventional antiseptic research from the early-mid 20th Century. Many examples of dyes exist having conventional antimicrobial activity among the azine, acridine and triphenylmethane families which have since also been found to exhibit photosensitising capabilities. The prior employment of these examples in human antisepsis provides a practical basis in terms of low host toxicity, while extant structure-activity relationships for conventional antimicrobial activity can support the development of similar relationships for photoactivated cell killing...
June 15, 2018: Photochemical & Photobiological Sciences
Keiko Kawauchi, Wataru Sugimoto, Takatoshi Yasui, Kohei Murata, Katsuhiko Itoh, Kazuki Takagi, Takaaki Tsuruoka, Kensuke Akamatsu, Hisae Tateishi-Karimata, Naoki Sugimoto, Daisuke Miyoshi
Aberrant activation of RAS signalling pathways contributes to aggressive phenotypes of cancer cells. The RAS-targeted therapies for cancer, therefore, have been recognised to be effective; however, current developments on targeting RAS have not advanced due to structural features of the RAS protein. Here, we show that expression of NRAS, a major isoform of RAS, can be controlled by photo-irradiation with an anionic phthalocyanine, ZnAPC, targeting NRAS mRNA. In vitro experiments reveal that ZnAPC binds to a G-quadruplex-forming oligonucleotide derived from the 5'-untranslated region of NRAS mRNA even in the presence of excess double-stranded RNA, which is abundant in cells, resulting in selective cleavage of the target RNA's G-quadruplex upon photo-irradiation...
June 11, 2018: Nature Communications
Wen Yi Jiang, Yuan Li, Zhi Ying Li, Zong Jie Cui
The G protein-coupled cholecystokinin 1 receptor (CCK1R) is activated permanently by type II photodynamic action (i.e., by singlet oxygen) in the freshly isolated rat pancreatic acini, in contrast to reversible activation by CCK. But how CCK1R is photodynamically activated is not known. Therefore, in the present work, we subjected membrane proteins extracted from isolated rat pancreatic acini to photodynamic action with photosensitiser sulphonated aluminium phthalocyanine (SALPC), and used reducing gel electrophoresis and Western blot to detect possible changes in CCK1R oligomerization status...
June 4, 2018: Cellular and Molecular Neurobiology
Iman M N Hamdan, Ismaiel A Tekko, Kyle B Matchett, Luis G Arnaut, Claudia S Silva, Helen O McCarthy, Ryan F Donnelly
Nodular basal cell carcinoma is a deep skin lesion and one of the most common cancers. Conventional photodynamic therapy (PDT) is limited to treatment of superficial skin lesions. The parenteral administration of near infrared (NIR) preformed photosensitisers suffers from poor selectivity and may result in prolonged skin photosensitivity. Microneedles (MN) can provide localised drug delivery to skin lesions. Intradermal delivery of the preformed NIR photosensitiser; 5,10,15,20-tetrakis(2,6-difluoro-3-N-methylsulfamoylphenyl bacteriochlorin (Redaporfin™™) using dissolving MN was successful in vitro and in vivo...
June 1, 2018: Journal of Pharmaceutical Sciences
Moritz F Kuehnel, Constantin D Sahm, Gaia Neri, Jonathan R Lee, Katherine L Orchard, Alexander J Cowan, Erwin Reisner
A precious metal and Cd-free photocatalyst system for efficient CO2 reduction in water is reported. The hybrid assembly consists of ligand-free ZnSe quantum dots (QDs) as a visible-light photosensitiser combined with a phosphonic acid-functionalised Ni(cyclam) catalyst, NiCycP. This precious metal-free photocatalyst system shows a high activity for aqueous CO2 reduction to CO (Ni-based TONCO > 120), whereas an anchor-free catalyst, Ni(cyclam)Cl2 , produced three times less CO. Additional ZnSe surface modification with 2-(dimethylamino)ethanethiol (MEDA) partially suppresses H2 generation and enhances the CO production allowing for a Ni-based TONCO of > 280 and more than 33% selectivity for CO2 reduction over H2 evolution, after 20 h visible light irradiation ( λ > 400 nm, AM 1...
March 7, 2018: Chemical Science
Shuai Dong, Hongxi Shi, Xintong Zhang, Xi Chen, Donghui Cao, Chuanbin Mao, Xiang Gao, Li Wang
Background: Candida albicans is the most prevalent fungal pathogen of the human microbiota, causing infections ranging from superficial infections of the skin to life-threatening systemic infections. Due to the increasing occurrence of antibiotic-resistant C. albicans strains, new approaches to control this pathogen are needed. Photodynamic inactivation is an emerging alternative to treat infections based on the interactions between visible light and photosensitisers, in which pheophorbide a (PPA) is a chlorophyll-based photosensitizer that could induce cell death after light irradiation...
2018: International Journal of Nanomedicine
Ross W Hogue, Olivier Schott, Garry S Hanan, Sally Brooker
17 Cobalt complexes - eleven dinuclear cobalt(II) complexes and three tetranuclear cobalt complexes (two mixed valent) of ditopic ligands with varying N-donor aromatic bridging moieties and pendant pyridine side arms, as well as three mononuclear cobalt(II) complexes of Schiff base macrocyclic ligands - have been screened for photocatalytic hydrogen evolution reaction (HER) activity. All 17 complexes are active catalysts for HER, in both DMF and aqueous solution, in tandem with the [Ru(bpy)3]2+ (bpy = 2,2'-bipyridine) photosensitiser...
April 19, 2018: Chemistry: a European Journal
Huguette Savoie, Carlotta Figliola, Estelle Marchal, Bry W Crabbe, Geniece L Hallett-Tapley, Ross W Boyle, Alison Thompson
The photo-induced cytotoxicity of prodigiosenes is reported. One prodigiosene represents a synthetic analogue of the natural product prodigiosin, and two are conjugated to molecules that target the estrogen receptor (ER). A comparison of incubation and irradiation frameworks for the three prodigiosenes is reported, with activity against ER- and ER+ lines explored. Furthermore, the ability of the three prodigiosenes to photosensitise the production of singlet oxygen is demonstrated, shedding mechanistic light onto possible photodynamic therapeutic effects of this class of tripyrroles...
May 16, 2018: Photochemical & Photobiological Sciences
Lizette Anayo, Anette Magnussen, Alexis Perry, Mark Wood, Alison Curnow
OBJECTIVES: Non-melanoma skin cancers are the most frequently occurring type of cancer worldwide. They can be effectively treated using topical dermatological photodynamic therapy (PDT) employing protoporphyrin IX (PpIX) as the active photosensitising agent as long as the disease remains superficial. Novel iron chelating agents are being investigated to enhance the effectiveness and extend the applications of this treatment modality, as limiting free iron increases the accumulation of PpIX available for light activation and thus cell kill...
March 31, 2018: Lasers in Surgery and Medicine
Renato Sonchini Gonçalves, Gabriel Batista César, Patrícia Magalhães Barbosa, Noboru Hioka, Celso Vataru Nakamura, Marcos Luciano Bruschi, Wilker Caetano
Emodin reduction to emodin anthrone comprise one of three process steps involved in the hypericin synthesis, a powerful natural photosensitiser found in plants of the genus Hypericum. In this communication, an optimized protocol was established for emodin reduction enabling an efficient multigram preparation of emodin anthrone. A screening of reducing agent (SnCl2 ·2H2 O and HClconc ) under different reaction times was employed in micro-scale and monitored by electronic absorption spectroscopy technique. Data showed lower yields of emodin anthrone when some experimental conditions previously described in the literature were reproduce...
March 30, 2018: Natural Product Research
María E Alea-Reyes, Oriol Penon, Paula García Calavia, María J Marín, David A Russell, Lluïsa Pérez-García
HYPOTHESIS: Metalloporphyrins are extensively investigated for their ability to form reactive oxygen species and as potent photosensitisers for use in photodynamic therapy. However, their hydrophobicity generally causes solubility issues concerning in vivo delivery due to lack of distribution and low clearance from the body. Immobilising porphyrins on carriers, such as gold nanoparticles (GNP), can overcome some of these drawbacks. The mode of assembling the porphyrins to the carrier influences the properties of the resulting drug delivery systems...
July 1, 2018: Journal of Colloid and Interface Science
Jane Dobson, Genilson Fernandes de Queiroz, Jon P Golding
Photodynamic therapy (PDT) is an evolving method of treating superficial tumours that is non-invasive and carries minimal risk of toxicity. It combines tumour-selective photosensitiser dyes, tissue oxygen and targeted illumination to generate cytotoxic reactive oxygen species (ROS) within the tumour. In addition to directly acting on tumour cells, PDT damages and restricts tumour microvasculature, and causes a local inflammatory response that stimulates an immune response against the tumour. Unlike surgery or radiotherapy, the surrounding extracellular matrix is unaffected by PDT; thus, tissue healing is excellent and PDT seldom causes scars...
March 2018: Veterinary Journal
Y Lu, R Conway-Kenny, J Wang, X Cui, J Zhao, S M Draper
A series of new Ir(iii) complexes incorporating 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (coumarin 6) and ethynylpyrene (EP) functionalised 1,10-phenanthroline (phen) were developed. [Ir(iii)(coumarin 6)2 (3-EP-phen)](PF6 ) (Ir-3) proved to be the most promising material in triplet photosensitising applications. Highly absorbing at λ = 485 nm (ε = 1.31 × 105 M-1 cm-1 ), it exhibits high upconversion and singlet oxygen quantum yields (ΦUC = 27.5%, ΦΔ = 81.5%) and an exemplary upconversion capability (η = 3...
February 12, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Colin A Morton
Photodynamic therapy (PDT), using topically administered photosensitizing agents, is widely approved as a treatment for certain nonmelanoma skin cancers. As a tissue-sparing non-surgical modality, there is great potential for PDT to enhance the choice of therapies available to treat, and potentially prevent, skin cancer. Treatment-specific guidelines have assessed the evidence for various photosensitizing agents and light sources, dosimetry, and evaluate reported adverse effects. Discomfort is frequently experienced during treatment but no analgesia was required in most pivotal lesion-directed studies...
February 7, 2018: Giornale Italiano di Dermatologia e Venereologia: Organo Ufficiale, Società Italiana di Dermatologia e Sifilografia
Mateo Jelovica, Petra Grbčić, Martina Mušković, Mirela Sedić, Sandra Kraljević Pavelić, Martin Lončarić, Nela Malatesti
A series of N-methylated and N-oxidised tripyridyl porphyrins were synthesised, characterised, and their PDT activity was studied with six cell lines. All the tested porphyrins with a long alkyl chain, except one, were more efficient for PDT than an N-methylated hydrophilic porphyrin and N-oxidised porphyrin without the long alkyl chain. Generally, N-methylated tripyridyl porphyrins were more active than those N-oxidised, but IC50 values for phototoxicity of two N-oxides, named TOPyP3-C17 H33 O and TOPyP3-C17 H35 , were still in the nanomolar concentration range for most of the tested cell lines...
February 20, 2018: ChemMedChem
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