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New Findings on Biological Pigments from Texas Christian University Summarized [Formation and thermodynamic stability of (polymer plus porphyrin)...

July 1, 2014

New Findings on Biological Pigments from Texas Christian University Summarized [Formation and thermodynamic stability of (polymer plus porphyrin) supramolecular structures in aqueous solutions]

By a News Reporter-Staff News Editor at Life Science Weekly -- A new study on Biological Factors is now available. According to news reporting from Fort Worth, Texas, by NewsRx journalists, research stated, "Optical properties of porphyrins can be tuned through (polymer + porphyrin) (host + guest) binding in solution. This gives rise to the formation of supramolecular structures."

The news correspondents obtained a quote from the research from Texas Christian University, "In this paper, the formation, thermodynamic stability and spectroscopic properties of (polymer + porphyrin) supramolecular structures and their competition with porphyrin self-association were investigated by both isothermal titration calorimetry (ITC) and absorption spectroscopy. Specifically, reaction enthalpies and equilibrium constants were measured for meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS) self-association and TPPS binding to the polymer poly(vinylpyrrolidone) (PVP, 40 kg/mol) in aqueous solutions at pH 7 and three different temperatures (12, 25 and 37 degrees C). ITC, compared to spectroscopic techniques, provides two independent means to determine reaction enthalpies: direct measurements and Van't Hoff plot. This was used as a criterion to assess that (1) self-association of TPPS is limited to the formation of dimers and (2) TPPS binds to PVP in its monomeric state only. The formation of TPPS dimers and (PVP + TPPS) supramolecular structures are both enthalpically driven. However, (polymer + porphyrin) binding was found to be entropically favored compared to dimerization. Furthermore, the reaction enthalpies of these two processes significantly depend on temperature. This behavior was attributed to hydrophobic interactions. Finally, the limiting absorption spectra of monomeric, dimeric and polymer-bound states of TPPS were extracted from our spectroscopic measurements combined with the thermodynamic parameters obtained by ITC. The observed spectral shifts indicate that the two hydrogens in the central porphyrin are involved in (PVP + TPPS) binding."

According to the news reporters, the research concluded: "This work provides valuable information on thermodynamic stability of (polymer + porphyrin) supramolecular nanostructures and the general understanding of complex competing associative processes in solution."

For more information on this research see: Formation and thermodynamic stability of (polymer plus porphyrin) supramolecular structures in aqueous solutions. Journal of Chemical Thermodynamics, 2014;75():119-127. Journal of Chemical Thermodynamics can be contacted at: Academic Press Ltd- Elsevier Science Ltd, 24-28 Oval Rd, London NW1 7DX, England. (Elsevier -; Journal of Chemical Thermodynamics -

Our news journalists report that additional information may be obtained by contacting V.C.P. da Costa, Texas Christian Univ, Dept. of Chem, Fort Worth, TX 76129, United States. Additional authors for this research include B.J. Hwang, S.E. Eggen, M.J. Wallace and O. Annunziata (see also Biological Factors).

Keywords for this news article include: Texas, Fort Worth, Porphyrins, United States, Nanotechnology, Supramolecular, Biological Factors, Biological Pigments, Emerging Technologies, North and Central America

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Source: Life Science Weekly

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