Guar Gum and Scleroglucan Interactions with Borax: Experimental and Theoretical Studies of an Unexpected Similarity

Bocchinfuso, Gianfranco; Meisina, Claudia; Sandolo, Chiara; Margheritelli, Silvia; Alhaique, Franco; Coviello, Tommasina; Palleschi, Antonio

doi:10.1021/jp105838t

Cited by 52 publications

(38 citation statements)

References 79 publications

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“…On the other side, SCLG requires several hours for gelation in the presence of borax and no self-healing occurs. Nevertheless, both, GG and SCLG, in the presence of borax, are capable to give self-sustaining gels [28]. Furthermore, also the interaction with borax takes place in a different way.…”

Section: Introductionmentioning

confidence: 98%

“…During the swelling the labile nature of the borax cross-links in the GG makes the interchain interactions able to undergo the needed rearrangement, similar to that of SCLG where full chemical bridges are not present. These similarities explain the quite unexpected parallel swelling behaviour of GG and SCLG, in the presence of borax [16,28]. However, in all these previous research works, no attention was specifically focused on the estimation of the mesh sizes of the networks, a very important parameter for the numerous implications that it may have on these hydrogel systems when used for industrial and/or pharmaceutical applications.…”

Section: Introductionmentioning

confidence: 99%

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Guar gum/borax hydrogel: Rheological, low field NMR and release characterizations

Coviello¹,

Matricardi²,

Alhaique³

et al. 2013

Express Polym. Lett.

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Abstract. Guar gum (GG) and Guar gum/borax (GGb) hydrogels are studied by means of rheology, Low Field Nuclear Magnetic Resonance (LF NMR) and model drug release tests. These three approaches are used to estimate the mesh size (!) of the polymeric network. A comparison with similar Scleroglucan systems is carried out. In the case of GGb, the rheological and Low Field NMR estimations of ! lead to comparable results, while the drug release approach seems to underestimate !. Such discrepancy is attributed to the viscous effect of some polymeric chains that, although bound to the network to one end, can freely fluctuate among meshes. The viscous drag exerted by these chains slows down drug diffusion through the polymeric network. A proof for this hypothesis is given by the case of Scleroglucan gel, where the viscous contribution is not so significant and a good agreement between the rheological and release test approaches was found. Vol.7, No.9 (2013) 733-746 Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2013.71 * Corresponding author, e-mail: mariog@dicamp.univ.trieste.it © BME-PT mation in aqueous solution and a single coiled disordered conformation in methylsulphoxide or at high pH values (NaOH$>0.2 M) [10,11]. Due to its peculiar properties, SCLG was extensively used for various commercial applications (secondary oil recovery, ceramic glazes, food, paints, cosmetics, etc.) [12] and it was also investigated for modified/ sustained release formulations and ophthalmic preparations [13]. Actually, it is well known that borax is an efficient crosslinker for polymers bearing hydroxyl groups but the type of formed linkages is still debated and so far two main models have been proposed. The most popular one implies the existence of pure chemical crosslinks between the polymeric chains and borax [14], and it was proposed for the GG/ borax interactions. According to the other model, the borax ions hold together the polymeric chains by means of mixed physical/chemical linkages. This model was firstly proposed for poly-(vinylalcohol) [15] and it was recently suggested also for SCLG [16,17]. The considerable effort devoted to the study of polymer-ion complexes is due to the wide range of application of these systems. In particular, the complex between GG and borate was previously studied by several authors [18,19] that investigated the effect of polymer and borate concentration, temperature, environmental pH conditions, and GG molecular weight on the peculiar rheological properties detected by the frequency dependence of relaxation spectra. Furthermore, a detailed study of the crosslinking reaction of borate ion with polyhydroxy polymers was carried out by means of 11 Keywords: polymer gels, rheology, low field NMR, transport processes, mesh-size eXPRESS Polymer Letters

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Guar gum/borax hydrogel: Rheological, low field NMR and release characterizations

Coviello¹,

Matricardi²,

Alhaique³

et al. 2013

Express Polym. Lett.

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“…In the last decade, by using both experimental and computational techniques, we investigated the drug release properties of tablets formed by Sclg, also in the presence of borax [3,5,[16][17][18][19][20][21]. During the water uptake process, a gel phase forms and the release of the drugs is related to their diffusion into the gel.…”

Section: Introductionmentioning

confidence: 99%

“…Ten years ago, for the first time, molecular dynamics simulations were applied by us to investigate the triplex at low and room temperature, to discuss its high stability, and to clarify the role of water molecules in the mobility of glucose rings in the Sclg side chains, involved in a conformational transition occurring at around 7 ∘ C [3]. MD simulations were also applied to show that the presence of borax does not change the intrinsic features of triplexes [18,19], while an opposite behaviour was observed in the case of the intrinsically disordered polysaccharides guar gum [21].…”

Section: Introductionmentioning

confidence: 99%

Relative Stability of the Scleroglucan Triple-Helix and Single Strand: an Insight from Computational and Experimental Techniques

Bocchinfuso

Meisina

Conflitti

et al. 2016

Zeitschrift Für Physikalische Chemie

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Scleroglucan (Sclg) is a polysaccharide that exhibits a triple helix conformation (triplex), both in aqueous solution and in the solid state, which is lost in DMSO solution, at high temperature and at high pH values. The triplex conformation is characterized by a high rigidity, responsible of Sclg peculiar properties. Although the relative stability of triplex and single strand has already been investigated, different structural details are still missing. In the present study, we analyse the structural properties and the factors stabilizing the single chain and the triple helix of Sclg in different conditions. To this end, we simulated both systems in water and in DMSO. The triple helix has been also simulated in the presence of chemical damages on one of the three strands (to reproduce in silico the effect of sonication) or by inducing a partial unfolding of the triplex structure. The computational results have been compared with experimental evidences in which the triplex denaturation, at alkaline pH values, has been followed by monitoring the UV and CD spectra of Congo red, used as a probe molecule. Our results indicate that sonication breaks the Sclg chains without appreciably changing the stability of the other tracts of triple helix. The simulated perturbed or partially unfolded triplexes show a clear tendency to form less Unauthenticated Download Date | 6/23/16 1:58 PM 2 | G. Bocchinfuso et al. ordered aggregates. Finally, our simulations put in evidence an important role of the hydrophobic interactions both in the triplex stability and in the aggregation processes observed after induced denaturation.

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“…The packed guar backbone when cross linked with zircon or boron provide an intense gel structure (Bocchinfuso et al, 2010), which is used as petroleum oil drilling mud. The plant biopolymer is widely used in ice creams for water crystal maintenance and mouth filling ability.…”

Section: Introductionmentioning

confidence: 99%

New water resistant biomaterial biocide film based on guar gum

Das

Ara

Dutta

et al. 2011

Bioresource Technology

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Guar Gum and Scleroglucan Interactions with Borax: Experimental and Theoretical Studies of an Unexpected Similarity

Cited by 52 publications

References 79 publications

Guar gum/borax hydrogel: Rheological, low field NMR and release characterizations

Guar gum/borax hydrogel: Rheological, low field NMR and release characterizations

Relative Stability of the Scleroglucan Triple-Helix and Single Strand: an Insight from Computational and Experimental Techniques

New water resistant biomaterial biocide film based on guar gum

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