The major cytotoxic agent with most current photosensitizers used in photodynamic therapy pdt is widely believed to be singlet oxygen 1 o 2. The purpose of this study is to investigate the feasibility for quantitative measurement of singlet oxygen 1 o 2 generation by using a newly developed 1 o 2specific fluorescence probe singlet oxygen sensor green reagent sosg. Quantum yield and mechanism of singlet oxygen generation. Preliminary evaluation suggested that ylgi was a promising photosensitizer for pdt. The quantum yield of singlet oxygen was precisely determined for riboflavin. Pdf determination of singlet oxygen quantum yield of. A new simpler relati ve method for estimating photosensitized singlet oxygen quantum yield has been developed. The influence of the support, silica, merrifield and other polymers, on the quenching of singlet oxygen were also evaluated. Hematoporphyrin ix dimethyl ester hpdme, tetraphenylporphyrin tpp, tetra4methoxyphenylporphyrin tmpp, tetra3.
Singlet oxygen quantum yields of potential porphyrin based. Nov 08, 2010 singlet oxygen 1 o 2 is widely considered to be the predominant cytotoxic agent for photodynamic therapy pdt, and the 1 o 2 quantum yield is a key characteristic for the newly developed photosensitizers. The yield is most likely held restricted by the solubility of molecular oxygen. The mechanism and spectral dependence of the quantum yield of singlet oxygen o2a 1. With the aim of improving the solubility of hematoporphyrin and its targeting efficiency versus.
The singlet oxygen quantum yield is a quantitative measurement of the efficiency in which photosensitizers are able to use energy, in the form of light, to convert oxygen in the. Semiconductor and carbon quantum dots in photodynamic. This quantity is defined as the number of molecules of 1 o 2 molecules generated for each photon absorbed by a photosensitiser. The singlet oxygen quantum yield f d is a key property of a photosensitising agent. Lifetime of singlet oxygen in solution directly determined by. The efficacy of a molecule to generate singlet oxygen is expressed by the quantum yield of singlet oxygen. Singlet molecularoxygen quantum yield measurements. Method for determination of singlet oxygen quantum yields for.
Yet even for standardized isolates such as those from the international humic substance society ihss, wideranging values exist in the literature. The fundamental prerequisite for optimal response to photosensitization is a sufficient amount of drug localized in. Feasibility study on quantitative measurements of singlet. High quantum yield of reactive oxygen species the type and quantity of ros generated by an excited. Dissolved organic matter singlet oxygen quantum yields. To avoid dimerization at these relatively large dye concentrations sodium dodecyl sulfate sds was added to the solution at final concentrations of 10 mmol l1.
The singlet oxygen formation quantum yield for solutions of the dication, freebase and metallated forms of hematoporphyrin derivative. The dominant channel of singlet oxygen generation with measured. The singlet oxygen quantum yield is a quantitative measurement of the efficiency in which photosensitizers are able to use energy, in the form of light, to convert oxygen in the ground state to the reactive species singlet oxygen, o21. Photodynamic antitumor efficiency of hematoporphyrin. Box 94, grahamstown 6140, south africa received 10 december 2002. The lowest excited state of the diatomic oxygen molecule is a singlet state. Thermallensing and phosphorescence studies of the quantum. In a large number of photooxidation reactions, the reactive inter mediate is singlet oxygen, which is most often produced by sensitization, i. Singlet oxygen as a mediator in the hematoporphyrin.
In terms of its chemical reactivity, however, singlet oxygen is far more reactive toward organic compounds. Quantum yield of singlet oxygen production by monomeric and aggregated forms of hematoporphyrin derivative article in free radical biology and medicine 302. Photochemistry and photophysics of thienocarbazoles. Platinum and palladium derivatives have been synthesised with singlet oxygen quantum yields of 0. However, d 2 o increased the yields only slightly, and the singlet oxygen. Method for determination of singlet oxygen quantum yields.
Novel approaches to singlet oxygen photosensitization in the nano. Evaluation of singlet oxygen luminescence of a novel. Watersoluble magnetic nanoparticles functionalized with. It is a gas with physical properties differing only subtly from those of the more prevalent triplet ground state of o 2. Photooxidation, supported catalysts, porphyrins, polymer, singlet oxygen introduction.
Singlet oxygen quantum yields of photosensitizers differ when measured in. Pdf singlet oxygen 1o2 is widely considered to be the predominant cytotoxic agent for photodynamic therapy pdt, and the 1o2 quantum. Singlet oxygen generation by uva light exposure of endogenous. Further, the increased absorption of light by water molecules.
From a preliminary study of aggregation of these dyes, it was established that uroporphyrin, hematoporphyrin and deuteroporphyrin allowed to investigate the. Oxygen dependence of the photosensitizing effect of. Quantum yield of singlet oxygen production by monomeric and. Formosinho1 chemistry department, university of coimbra, 3049 coimbra codex, portugal. In this study, 1 o 2 generation from the hiporfin is monitored indirectly by using the fluorescence probe singlet oxygen sensor green sosg. The photophysical property, cytotoxicity of hematoporphyrin derivative bl1 in vitro and in vivo were investigated as photosensitizer for photodynamic therapy pdt. Pdf quantum yield of singlet oxygen production by monomeric. The following photocharacterization must be accomplished to demonstrate the potential of any particular sensitizer for photosensitization activity. Singlet molecular oxygen quantum yield measurements of. Determination of singlet oxygen quantum yield of hiporfin. Singlet oxygen 1 o 2 generation quantum yields from chromophoric dissolved organic matter cdom have been reported for many samples over the past 4 decades. Determination of the 1o2 quantum yields for porphyrin.
The incidence of the use of three wavelengths of excitation on the calculation of the quantum yield have been described in detail in previous work. Lifetime and quantum yield of the singlet oxygen generated by hematoporphyrin in the methanol solution are well known. The oxidation of 1,3diphenylisobenzofuran by singlet oxygen was investigated in methanol and in two different types of liposomes. Thermallensing and phosphorescence studies of the quantum yield and lifetime of singlet molecular oxygen 1 delta g sensitized by hematoporphyrin and related porphyrins in deuterated and nondeuterated ethanols. Pdt has proven ability to kill microbial cells, including bacteria, fungi and viruses. Reaction not affected by potentiators and inhibitors of o. Comparable to exogenous photosensitizers, endogenous molecules absorb uva light in the skin and can generate singlet oxygen. Nonlinear least square analysis gives an excellent fit for the experimental values with. Detection of singlet state of oxygen 1o 2 is of particular interest in a multitude of applications such as photodynamic treatment of cancer1, fine chemical synthesis2 and treatment of wastewater3.
Lifetime of singlet oxygen in solution directly determined. Jul 31, 2007 the singlet oxygen formation quantum yield. Determination of the 1 o 2 quantum yields for porphyrinbased photosensitizers, including hematoporphyrin derivative hiporfin, hematoporphyrin monomethyl ether hmme and photocarcinorin psd007 in airsaturated dimethylformamide dmf solutions. Singlet oxygen generation by uva light exposure of. The singlet molecular oxygen quantum yield values of the above porphyrins and their metal derivatives in n,ndimethyl formamide dmf have been measured in the presence of 1,3diphenylisobenzofuran dpbf as1o2 acceptor using steady state technique after correcting for the intensity of light absorbed by the photosensitizers. Efficiency factors of singlet oxygen generation from tetrathiarubyrin bull. It is typically generated via energy transfer from the excited state of a photosensitizer to the oxygen molecule. The initial quantum yields of photobleaching, as measured in ph 7.
The ros generated during each process are also shown. The influence of the support on the singlet oxygen quantum. The singlet oxygen quantum yield of photodynamic agents was measured at 546 nm, 630 nm. Singlet oxygen generation by photodynamic agents sciencedirect. Singlet oxygen generation with chemical excitation of an. This protocol was performed 2 times, and the average value of the quantum yield was calculated. The results obtained with the photochemical systems are comparable with those obtained by the photophysical method. Pdf determination of singlet oxygen quantum yield of hiporfin. Singlet oxygen is the common name of an electronically excited state of molecular oxygen which is less stable than molecular oxygen in the electronic ground state. It is used clinically to treat a wide range of medical conditions, including. Superoxide, hydrogen peroxide and singlet oxygen in hematoporphyrin derivativecysteine, nadh and light systems garry r. Singlet oxygen quantum yields of different photosensitizers. The absorption spectra and singlet oxygen luminescence different solvents were evaluated. In this method a strong depletion signal is observed when porphyrin 211m and l.
Determination of singlet oxygen quantum yields with 1,3diphenylisobenzofuran in model membrane systems. Measurement of the singlet oxygen quantum yields singlet oxygen quantum yields were calculated according to the leterature. A zincmetallated secoporphyrazine has a high quantum singlet oxygen yield 0. Quantum yield of singlet oxygen production by monomeric. This value of singlet oxygen quantum yield is higher than the other photosensitizers such as hematoporphyrin0. Effect of hematoporphyrin derivative concentration on the quantum yield. Relative quantum yields for singlet oxygen formation in a 50 hematoporphyrin solution in pbs x and for hpdsensitized photoinactivation of nhik 3025 cells o determined at different 02 levels. Bdt can be used as quencher in different solvents to determine. Most known photosensitizers used in pdt represent type ii photochemical reaction when energy transfer to molecular oxygen 3o 2 occurs to yield very reactive singlet oxygen 1o 2. Singlet molecularoxygen quantum yield measurements of. Lifetime and quantum yield of the singlet oxygen generated by hematoporphyrin in the methanol solution are. Singlet molecular oxygen quantum yield measurements of some.
Strong absorption and high singlet oxygen quantum yield of compound bl1 were exhibited. However, in micellar solution, chain reactions occur when dpbf is used as. In comparison to the chemical methods the luminescence method exhibits the advantage that side reactions of the quencher are excluded. In general, the singlet oxygen quantum yields are higher in dmf than in 0. Singlet oxygen generation by photodynamic agents, journal of. This expanded porphyrinlike photosensitiser has shown the best singlet oxygen photosensitising ability of any of the reported secoporphyrazines. The singlet oxygen quantum yield was estimated to be 0. Photodynamic antitumor efficiency of hematoporphyrin derivative. The method used for measuring singlet oxygen production quantum yields has been fully described elsewhere, and is illustrated below. The methodology or technique used to measure the qa value for each entry is given and ranges from direct detection of the luminescence produced on relaxation of singlet oxygen.
The photochemical dpbf method results in absolute values of. The singlet molecular oxygen quantum yield phidelta values of the above porphyrins and their metal derivatives in n,ndimethyl formamide dmf have been measured in the presence of 1, 3diphenylisobenzofuran dpbf as o12 acceptor using steady state technique after correcting for the intensity of light absorbed by the photosensitizers. Relative quantum yields for singlet oxygen formation in a 50 nadh and light systems garry r. Hall laboratory of molecular biophysics, national institute of enoironmental health sciences, research triangle park, nc u. Determination of the singlet oxygen quantum yield of bacteriochlorin a. Determination of the singlet oxygen quantum yield of. Singlet oxygen production by uv and visible photoexcited. Significant phototoxicity and inhibition to tumor were also showed. Singlet oxygen quantum yields from halogenated chlorins. Superoxide, hydrogen peroxide and singlet oxygen in. Efficiency factors of singlet oxygen generation from core. Aug 23, 2012 the purpose of this study is to investigate the feasibility for quantitative measurement of singlet oxygen 1o2 generation by using a newly developed 1o2specific fluorescence probe singlet oxygen sensor green reagent sosg. A compilation of singlet oxygen yields from biologically.
Tryptophan photosensitization was used to determine the quantum yield of singlet oxygen production by porphyrins irradiated with ultraviolet or visible light in phosphate buffer at ph 7. The fundamental prerequisite for optimal response to photosensitization is a sufficient amount of drug localized in the target tissue. Singlet oxygen generation by photodynamic agents singlet oxygen generation by photodynamic agents fernandez, jim m. The molecular weight of hpd being uncontrolled, all. However, we estimated the chemical yield of singlet oxygen on the basis of the concentration of compound 11 and the decrease in the absorption of dpbf as 4. Quantum yield of singlet oxygen production by monomeric and aggregated forms of hematoporphyrin derivative.