Cyanines during the 1990s: A Review

Anti-cancer drugs

Methylene blue in photodynamic therapy: From basic mechanisms to clinical applications.

Coumarins, as a family of molecules, exhibit a wide range of fluorescence emission properties. In many cases, this fluorescence is extremely sensitive to the local environment of the molecule, especially the local polarity and microviscosity. In addition, coumarins show a wide range of size, shape, and hydrophobicity. These properties make them especially useful as fluorescent probes of heterogeneous environments, such as supramolecular host cavities, micelles, polymers and solids. This article will review the use of coumarins to probe such heterogeneous systems using fluorescence spectroscopy.

https://www.mdpi.com/1420-3049/14/1/210/pdf

The use of coumarins as environmentally-sensitive fluorescent probes of heterogeneous inclusion systems

The cationic styryl dye DSMI binds to the double helical DNA with a high affinity. A red shift of the absorption spectrum and hypochromism accompany the binding of DSMI to calf thymus DNA. The fluorescence yields increase dramatically when DSMI binds to DNA, with no shifts in the emission maximum. These spectral changes are in contrast to the behavior observed with many fluorescent intercalators. Groove binding rather than intercalation of the dye was suggested to be the cause of these spectral changes, based on a variety of experimental results. Consistent with groove binding, the fluorescence enhancements were greater with poly(dA—dT) when compared with poly(dG—dC). The addition of salt or a strong electrolyte to the solution releases the DNA-bound dye cations from the groove and causes a decrease in the fluorescence yield. Therefore, when the dye binds to DNA, the fluorescence quenching with anionic quenchers was enhanced dramatically, in contrast to the expected protection of the probe fluorescence by the DNA helix. Binding of DSMI to DNA inhibits the non-radiative deactivation of the excited state, perhaps owing to the restriction imposed by the narrow minor groove of the DNA. The steric constraints imposed on the dye owing to the binding in the groove result in enhanced fluorescence yields and longer fluorescence lifetimes. Since the lifetimes of the DNA-bound dye were still in the nanosecond range, it is very likely that groove binding of the dye permits twisting in the excited state, which may be important in the excited state dynamics of this class of dyes. The large fluorescence enhancements observed when DSMI binds to the helix and the poor fluorescence yield of the dye in the absence of DNA suggests that DSMI should be quite useful in the staining of DNA gels and for the detection of very low concentrations of DNA.

Groove binding of a styrylcyanine dye to the DNA double helix : the salt effect

Photochemical and thermal cis/trans isomerization is reported for a stilbazolium betaine (M). Obtained from syn- thesis in the trans configuration, M cannot be isomerized directly but only via the 0-protonated form MHn,,, yields the cis isomer MH& (structure established by IH NMR) which can be deprotonated to the cis betaine. M,i, represents the first example of a cis isomer in this class of compounds. Though fairly stable in aqueous solution, M,i, can be fully reverted to the trans isomer either thermally or photochemically. The sequence M,,,,, s MH:,,, F! MH;, ~i M,i, - M,,,,, constitutes a complete molecular reaction cycle which may serve as a chemical model for the storage of information and subsequent regeneration of the information carrier, for instance, in biological systems.

/pdf/photochemical-cis-trans-isomerization-of-a-stilbazolium-a8rhx9ylpf.pdf

Photochemical cis/trans isomerization of a stilbazolium betaine. A protolytic/photochemical reaction cycle

Photodynamic therapy (PDT) is a form of phototherapy that involves three key components: a photosensitizer, a light source, and tissue oxygen. When these components are combined together, they become toxic to the targeted cells.

History of Photodynamic Therapy

Synthesis and tautomeric structure of novel 3,7-bis(arylazo)-2,6-diphenyl-1H-imidazo-[1,2-b]pyrazoles in ground and excited states

Chlorophyll derivative mediated PDT versus methotrexate: an in vitro study using MCF-7 cells.

Ethosomes and lipid-coated chitosan nanocarriers for skin delivery of a chlorophyll derivative: A potential treatment of squamous cell carcinoma by photodynamic therapy.

Mahmoud H. Abdel-Kader

Papers

Photochemical cis/trans isomerization of a stilbazolium betaine. A protolytic/photochemical reaction cycle

History of Photodynamic Therapy

Synthesis and tautomeric structure of novel 3,7-bis(arylazo)-2,6-diphenyl-1H-imidazo-[1,2-b]pyrazoles in ground and excited states

Chlorophyll derivative mediated PDT versus methotrexate: an in vitro study using MCF-7 cells.

Ethosomes and lipid-coated chitosan nanocarriers for skin delivery of a chlorophyll derivative: A potential treatment of squamous cell carcinoma by photodynamic therapy.