Photosensitizer immobilization

Few papers have described photodynamic effects produced by PAH s in larger aquatic organisms. Morgan and Warshawsky compared the rates of photosensitized immobilization of nauplii of the brine shrimp Artemia salina induoed by nineteen carcinogenic and twenty-... 

Immobilization of (3-D-glucosidase from almonds on photo-crosslinkable resin prepolymer (ENTP-4000) was carried out by the following procedure. One gram of ENTP-4000 was mixed with 10 mg of a photosensitizer, benzoin ethyl ether, and 110 mg of (3-D-glucosidase from almonds (3.4 units mg ). The mixture was layered on a sheet of transparent polyester film (thickness, ca. 0.5 mm). The layer was covered with transparent thin film and then illuminated with chemical lamps (wavelength range 300 00 nm) for 3 min. The gel film thus obtained was cut into small pieces (0.5 x 5 x 5 mm) and used for bioconversion reaction. 

Run/Nin heteronuclear complexes such as (653), in which a photosensitizer [Ru(bpy)3]2+ or [Ru(phen)3]2+ is covalently attached to the Ni1 cyclam complex, have been synthesized in order to improve the efficiency of electron transfer from the photoexcited photosensitizer to the catalytic site.1 44-1646 However, these complexes did not perform particularly well, either due to unfavorable configuration of the Nin-cyclam subunit and the resulting steric hindrance or due to short lifetime of the excited states of the Ru photosensitizer moieties. A stable catalytic system has been prepared by immobilizing macrocyclic Ni11 complexes and [Ru(bipy)3]2+ in a nafion membrane.164... 

The optode transduces the non-optical signal from the environment to the optical one, readable by the photodetector. Various indirect optical sensors and theirs applications are described in literature35. The optode can work as a chemical sensor that detects certain analytes in aqueous solutions or in air on chemical way. It means that changes in the environment cause the changes in the photosensitive material, which is immobilized in the optode matrix. These chemical changes influence the observed light intensity (for example, due to absorption) or one can analyze the intensity or time decay of luminescence. There are numbers of publications devoted to the family of optical chemical sensors36. 

The sNPS photosensitivity increased after the immobilization of antibodies but it rose sharply following the addition of T2 mycotoxin at the concentration of 100 ng/mL (Fig. 9.7). 

This approach can be further extended to photoelectrochemical reactions at modified semiconductor electrodes. In such cases the immobilized substance(s) may serve several functions mediation of the redox process, photosensitization of the semiconductor, and photocorrosion protection. 

Several studies have investigated the use of photosensitized reactions to remove triazines from water. For example, complete mineralization of several triazine herbicides was observed when aqueous solutions of these herbicides were photolyzed in the presence of titanium dioxide immobilized in a photocatalytic membrane. 

A closely related organized microheterogeneous system has been composed of a Si02 colloid on which a Pd catalyst is immobilized, and the photosystem includes eosin, Eo2 (2), as photosensitizer, iV,A -dibenzyl-4,4 -(3,3 -dimethyl)bipyridinium, BMV2+ (15), as electron relay and TEOA as electron donor [137]. In a... 

Fig. 25. Cyclic photolysis of water using Ru(bpy)f+ as photosensitizer and an immobilized catalytic assembly composed of Ti02/Pt/Ru02. The semiconductor Ti02 component acts as electron carrier to the Pt catalyst...

H., Baba, T., Iseki, Y., Endo, A., Adachi, C., Watanabe, M. and Hisaeda, Y. (2008) Photosensitizing properties of the porphycene immobilized in sol-gel-derived silica coating films. Tetrahedron Letters, 49 (43), 6198-6201. 

The thin semiconductor particulate film prepared by immobilizing semiconductor nanoclusters on a conducting glass surface acts as a photosensitive electrode in an electrochemical cell. An externally applied anodic bias not only improves the efficiency of charge separation by driving the photogenerated electrons via the external circuit to the counter electrode compartment but also provides a means to carry out selective oxidation and reduction in two separate compartments. This technique has been shown to be veiy effective for the degradation of 4-chlorophenol [116,117], formic acid [149], and surfactants [150] and textile azo dyes [264,265]. 

Achiral cis-1,2-diphenylcyclopropane photoisomerizes to the chiral trans isomer upon singlet- or triplet-photosensitized irradiation [64-67], It is expected that the reactant and chiral inductor immobilized in a zeolite supercage interact intimately with each other to afford more efficient photochirogenesis. Ramamurthy and coworkers reported that the enantio- and diastereodifferentiating photoisomeriza-tions of ris-2p,3p-diphenyl-la-cyclopropanecarboxylates 20 (Scheme 7) in chirally modified zeolite supercages lead to the corresponding chiral trans isomer 21 [68]. 

An intriguing logical extension of such work is the construction of a supramolecular host modified with a chiral sensitizer for executing enantiodifferentiating photosensitization. Inoue and coworkers reported a novel supramolecular photochirogenic system, in which an optically active sensitizer immobilized in zeolite supercages sensitizes the enantiodifferentiating photoisomerization of an excess amount of substrate dissolved in bulk solution [90]. 

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