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Molecules 2017, 22(3), 435;

The Influence of pH on the Scleroglucan and Scleroglucan/Borax Systems

Department of Chemical Sciences and Technologies, University of Rome “Tor Vergata”, Via della Ricerca Scientifica, 00133 Rome, Italy
Department of Engineering and Architecture, University of Trieste, P.le Europa 1, 34127 Trieste, Italy
Department of Drug Chemistry and Technologies, “Sapienza”, University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
Author to whom correspondence should be addressed.
Academic Editor: Derek J. McPhee
Received: 9 January 2017 / Revised: 3 March 2017 / Accepted: 6 March 2017 / Published: 9 March 2017
(This article belongs to the Section Medicinal Chemistry)
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The effects that an increase of environmental pH has on the triple helix of scleroglucan (Sclg) and on the Sclg/borax hydrogel are reported. Rheological experiments show that the hydrogel is less sensitive to pH increase than Sclg alone, while at pH = 14 a dramatic viscosity decrease takes place for both systems. This effect is evidenced also by the reduced water uptake and anisotropic elongation detected, at pH = 14, by the swelling behaviour of tablets prepared with the Sclg/borax system. On the opposite, a different behaviour was observed with guar gum and locust bean gum tablets, tested as reference polysaccharides. The effect of pH on the structure of Sclg and Sclg/borax was investigated also by means of spectroscopic approaches based on the interaction between Congo red (CR) and the Sclg triple helix. Obtained results indicated that the CR absorbance maximum is shifted as a function of pH and by the presence of borax. Principal component analysis allowed very precise identification of the pH value at which the Sclg helix collapses. Molecular dynamics simulations of the Sclg/borax–CR complex indicated that, at physiological pH, only a few ordered configurations are populated, according to the induced circular dichroism (CD) spectrum evidence. View Full-Text
Keywords: scleroglucan; rheology; swelling; Congo red; molecular dynamics simulations; principal component analysis scleroglucan; rheology; swelling; Congo red; molecular dynamics simulations; principal component analysis

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Mazzuca, C.; Bocchinfuso, G.; Palleschi, A.; Conflitti, P.; Grassi, M.; Di Meo, C.; Alhaique, F.; Coviello, T. The Influence of pH on the Scleroglucan and Scleroglucan/Borax Systems. Molecules 2017, 22, 435.

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