There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Photodynamic therapy (PDT) is a clinically approved, minimally invasive therapeutic procedure that can exert a selective cytotoxic activity toward malignant cells. The procedure involves administration of a photosensitizing agent followed by irradiation at a wavelength corresponding to an absorbance band of the sensitizer. In the presence of oxygen, a series of events lead to direct tumor cell death, damage to the microvasculature, and induction of a local inflammatory reaction. Clinical studies revealed that PDT can be curative, particularly in early stage tumors. It can prolong survival in patients with inoperable cancers and significantly improve quality of life. Minimal normal tissue toxicity, negligible systemic effects, greatly reduced long-term morbidity, lack of intrinsic or acquired resistance mechanisms, and excellent cosmetic as well as organ function-sparing effects of this treatment make it a valuable therapeutic option for combination treatments. With a number of recent technological improvements, PDT has the potential to become integrated into the mainstream of cancer treatment. CA Cancer J Clin 2011;61:250-281. V C

/pdf/photodynamic-therapy-of-cancer-an-update-4fcrlehb17.pdf

Photodynamic therapy of cancer: An update†‡

Heme-Containing Oxygenases

Photodynamic therapy (PDT) uses non-toxic photosensitizers and harmless visible light in combination with oxygen to produce cytotoxic reactive oxygen species that kill malignant cells by apoptosis and/or necrosis, shut down the tumour microvasculature and stimulate the host immune system. In contrast to surgery, radiotherapy and chemotherapy that are mostly immunosuppressive, PDT causes acute inflammation, expression of heat-shock proteins, invasion and infiltration of the tumour by leukocytes, and might increase the presentation of tumour-derived antigens to T cells.

/pdf/photodynamic-therapy-and-anti-tumour-immunity-3h4u2nk6bb.pdf

Photodynamic therapy and anti-tumour immunity

Two decades have passed since the discovery in liver microsomes of a haemprotein that forms a reduced-CO complex with the absorptive maximum of the Soret at 450 nm (Klingenberg, 1958; Garfinkel, 1958) and the identification of this protein as a new cytochrome: pigment cytochrome, P-450 (Omura and Sato, 1962, 1964a). In the intervening years, the study of cytochrome P-450 dependent monoxygenases has expanded exponentially. From the first crude attempts to solubilise a P-450 (Omura and Sato, 1963, 1964b) to the determination of the primary, secondary, and tertiary structure of cytochrome P-450cam by amino acid sequencing (Haniu et al., 1982a,b) and x-ray crystallography (Poulos et al., 1984) our understanding of this unique family of proteins has been advancing on all fronts. Since, perhaps, the greatest understanding of the structure and mechanism of P-450s has come from concentrated study of P-450cam of the Pseudomonas putida camphor-5-exo-hydroxylase, this review will concentrate on findings with P-450cam; attention will be drawn to parallel and contrasting examples from other P-450s as appropriate.

Structure and Chemistry of Cytochrome P450

Background: There is increasing concern over the local and systemic side effects of TiO2 and ZnO coated nanoparticles widely used in sun blockers. Objective:<

Stratum corneum is an effective barrier to TiO2 and ZnO nanoparticle percutaneous absorption.

The incorporation of proto-, uro- and hematoporphyrin in low density lipoproteins (LDL) of human blood has been studied by equilibrium dialysis, fluorescence and absorption spectroscopy. The lipoproteins may efficiently compete with albumin in the binding of protoporphyrin to human blood proteins in patients suffering from protoporphyria. It can be concluded that hydrophobic porphyrins bind to blood proteins.



The complexation of hydrophobic porphyrins in LDL is responsible not only for efficient photodynamic effect at the lipoprotein level, but also for photoinduced lipid peroxidation and for consumption of β-carotene incorporated into LDL which are one of their natural carriers. The water-soluble uroporphyrin, although an efficient photosensitizer for the LDL apoprotein photoinactivation, is much less efficient for lipid peroxidation and β-carotene bleaching. The 353 nm laser flash photolysis shows that porphyrin triplet states are not affected by the physiological β-carotene content of LDL but are fully accessible to oxygen.

Interaction of human serum low density lipoproteins with porphyrins: a spectroscopic and photochemical study

— The photophysical and photochemical properties of thiophene derivatives have been studied by fluorescence and by 353 nm laser flash spectroscopy. α-Terthienyl and its derivatives show a moderate fluorescence quantum yield (less than 0.1) in cyclohexane, ethanol, or TritonX–100 micelles. An additional thiophene ring increases this value to 0.2 in ethanol or micelles. The transient triplet state of the six thiophenes is characterized by strong absorptions (e⋍ 50000 M-1 cm-1) in the visible region. These triplet states are very long lived. They react with oxygen, producing singlet oxygen very efficiently because of their high quantum yield of triplet formation (0.1 to 0.3). They do not react with excellent hydrogen or electron donors such as indole, N-acetyl tryptophanamide or cysteine. The hydrophobic thiophenes investigated are, therefore, Type II photodynamic agents almost exclusively.

EXCITED STATE PROPERTIES OF ∝aL‐TERTHIENYL and RELATED MOLECULES

Pyropheophorbide-a Methyl Ester-mediated Photosensitization Activates Transcription Factor NF-κB through the Interleukin-1 Receptor-dependent Signaling Pathway

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2886%2980026-6

In vitro interaction of the photoactive anticancer porphyrin derivative photofrin II with low density lipoprotein, and its delivery to cultured human fibroblasts.

René Santus

Papers

Stratum corneum is an effective barrier to TiO2 and ZnO nanoparticle percutaneous absorption.

Interaction of human serum low density lipoproteins with porphyrins: a spectroscopic and photochemical study

EXCITED STATE PROPERTIES OF ∝aL‐TERTHIENYL and RELATED MOLECULES

Pyropheophorbide-a Methyl Ester-mediated Photosensitization Activates Transcription Factor NF-κB through the Interleukin-1 Receptor-dependent Signaling Pathway

In vitro interaction of the photoactive anticancer porphyrin derivative photofrin II with low density lipoprotein, and its delivery to cultured human fibroblasts.