Photo-cross linking

A formation of cross-linked hyaluronan could be achieved by UV-exposure. This is how two covalently linked hydrogels were produced and used in tissue engineering [42]. A modification of hyaluronan and other similar polymers by UV exposure with added photoactive molecules increases the biochemical functionality and mechanical stability of the 

The advantage of such method is that the product of HA photo reactive derivatization is a water-soluble compound. Before the process of photo-solidifying starts, when the three-dimensional web has not yet formed, unreactive toxic compounds with low molecular weight could be easily removed from the reaction zone. 

The natural biopolymers, to which HA belongs, are not polydispersed polymers due to the matrix nature of their synthesis. The nature of the biochemical synthesis is determined by the matrix the enzyme upon which the triopolymer is synthesized. Nevertheless, during biopolymer extraction and purification processes they degrade in one way or another. For example, polygalactomannan, different types of cellulose (wood or cotton), chitosan and hyaluronan are isolated as a wide range of the relatively narrow dispersed macromolecule fractions. 

The purification and isolation of the final product of the biochemical synthesis, as a rule, always provides a multimodal set of narrow fractions (multimodal type distribution is a mode in which more than one peak appears on the graph of the molecular weight distribution). This leads to the fact that during the binding of a polydisperse system under mild conditions 

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The depth of light energy penetration for a photo cross-linking (photo-initiated free-radical propagation reaction) process can be calculated as... 

Liu B, Lewis AK, Shen W (2009) Physical hydrogels photo-cross-linked from self- assembled macromers for potential use in tissue engineering. Biomacromolecules 10 3182-3187 Vandermeulen GWM, Tziatzios C, Duncan R et al (2005) Peg-based hybrid block copolymers containing alpha-helical coiled coil peptide sequences control of self- assembly and preliminary biological evaluation. Macromolecules 38 761-769... 

Trinh, X. A., Fukuda, J., Adachi, Y, Nakanishi, H., Norisuye, T. and Tran-Cong-Miyata, Q. (2007) Effects of elastic deformation on phase separation of a polymer blend driven by a reversible photo-cross-linking reaction. Macromolecules, 40, 5566-5574. 

Alley, S.C., Ishmael, F.T., Jones, A.D., and Benkovic, S.J. (2000) Mapping protein-protein interactions in the bacteriophage T4 DNA polymerase holoenzyme using a novel trifunctional photo-cross-linking and affinity reagent./. Am. Chem. Soc. 122, 6126-6127. 

For the continuous mode, we utilized a dynamic rheological technique, Fourier transform mechanical spectroscopy (FTMS) (77,75), which provided a powerful method for monitoring, simultaneously, the evolving dynamic moduli at several frequencies during the course of photo-cross-linking. In this technique, an oscillatory strain, y, was applied to the sample, such that... 

Liu and coworkers systematically used photo-cross-linking to stabilize micelles containing a PCEMA core [82]. The micellar characteristic features (Z, etc.) were not affected by the cross-linking process, as proven by SLS, DLS, TEM, and SEC. 

QUANTUM YIELD PHOTOCHROMISM PHOTO-CROSS-LINKING PHOTOAFFINITY LABELING PHOTODIMERIZATION PHOTOISOMERIZATION PHOTOLYSIS FLASH PHOTOLYSIS... 

Kanoh, N., Kyo, M., Inamori, K., Ando, A., Asami, A., N ao, A. and Osada H. (2006) SPR imaging of photo-cross-linked small-molecule arrays on gold. Anal. Chem. 78, 2226-2230. 

The subject of photo-cross-linking is reviewed thoroughly by Ranby et al. ... 

Scheme 5 Structures of Some Hetero-bifunctional Photo-cross-linking Reagents and Their Incorporation into Peptides...

In summary, the inherent chemical susceptibility of the arenediazonium-based photoaffinity ligands does not make them a popular tool for routine photo-cross-linking studies. Examples of arenediazonium-based photophores that have been incoporated into peptides are given in Table 3. 

Several applications of photoreactive peptides require the presence of a radionuclide to allow specific and sensitive detection of the photo-cross-linked conjugates. In several cases, radioiodination of tyrosyl moieties and radiolabeled Bolton-Hunter reagents have been used. However, the presence of a radiolabel within the benzophenone photophore is desirable, particularly when the objective is to identify the site of photo-insertion of benzophenone. To this end some radiolabeled, benzophenone-based compounds have been developed and used in peptide synthesis, in particular tritiated Phe(4-Bz) (Scheme 24)J2161 [1-14C-carboxy]-4-benzoylbenzoic acid,1221 and 4-benzoyl-(2,3-3H2)-dihydrocinnamic acid.[154l In addition, 4-(4-hydroxybenzoyl)phenylalanine (Scheme 25) has been directly radioiodinated with Na125I and Chloramine-T)151 ... 

X Mao, S Shuman. Vaccinia virus mRNA (guanine-7-)methyltransferase mutational effects on cap methylation and AdoHcy-dependent photo-cross-linking of the cap to the methyl acceptor site. Biochemistry 35 6900-6910, 1996. 

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