The Effect of Divalent Metals on the Properties of Alginate Solutions. I. Calcium Ions.

Smidsrød, Olav; Haug, Arne; Larsen, Bjørn; Gronowitz, Salo; Hoffman, Ragnar A.; Westerdahl, Anders

doi:10.3891/acta.chem.scand.19-0329

Cited by 93 publications

(45 citation statements)

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“…The calcium content of the sodium alginates employed in this study varies from 0.36% to 0.73% w/w. The corresponding molar ratios of calcium to sodium alginate monomer of the multiple batches range from 0.018 to 0.036, which is below the critical ratio (i.e., 0.05) for calcium to exert significant effect on the rheological properties of aqueous alginate solutions (33). The % G values of the multiple batches as determined in our laboratory range from 37% to 41%, within the range specified by the manufacturer.…”

Section: Calcium Content Chemical Composition and Intrinsic Viscosimentioning

confidence: 83%

“…The corresponding molar ratios of calcium to sodium alginate monomer range from 0.004 to 0.025. Since calcium/alginate monomer molar ratios below 0.05 have been reported to exert little or no effect on the apparent viscosities of aqueous alginate solutions measured at different rates of shear (33), the ratios determined for the sodium alginates used in this study do not warrant concerns regarding the possible untoward influence of calcium on sodium alginate solution rheology.…”

Section: Discussionmentioning

confidence: 99%

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Rheological Evaluation of Inter-grade and Inter-batch Variability of Sodium Alginate

et al. 2010

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Abstract. Polymeric excipients are often the least well-characterized components of pharmaceutical formulations. The aim of this study was to facilitate the QbD approach to pharmaceutical manufacturing by evaluating the inter-grade and inter-batch variability of pharmaceutical-grade polymeric excipients. Sodium alginate, a widely used polymeric excipient, was selected for evaluation using appropriate rheological methods and test conditions. The materials used were six different grades of sodium alginate and an additional ten batches of one of the grades. To compare the six grades, steady shear measurements were conducted on solutions at 1%, 2%, and 3% w/w, consistent with their use as thickening agents. Small-amplitude oscillation (SAO) measurements were conducted on sodium alginate solutions at higher concentrations (4-12% w/w) corresponding to their use in controlled-release matrices. In order to compare the ten batches of one grade, steady shear and SAO measurements were performed on their solutions at 2% w/w and 8% w/w, respectively. Results show that the potential interchangeability of these different grades used as thickening agents could be established by comparing the apparent viscosities of their solutions as a function of both alginate concentration and shear conditions. For sodium alginate used in controlled-release formulations, both steady shear behavior of solutions at low concentrations and viscoelastic properties at higher concentrations should be considered. Furthermore, among batches of the same grade, significant differences in rheological properties were observed, especially at higher solution concentrations. In conclusion, inter-grade and inter-batch variability of sodium alginate can be determined using steady shear and small-amplitude oscillation methods.

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Section: Calcium Content Chemical Composition and Intrinsic Viscosimentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Rheological Evaluation of Inter-grade and Inter-batch Variability of Sodium Alginate

et al. 2010

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“…Diffusion of NaCl from the draw solution to the feed, which can significantly affect cake layer ion concentration [7,17], may lead to differences in gel properties between FO and RO tests with alginate fouling and a draw solution of NaCl due to the ion exchange 29 reaction between sodium and calcium ions in alginate gels [43]. LeRoux et al [44] measured compressive and shear moduli of alginate gels in calcium chloride solutions with and without sodium chloride and found that compressive and shear moduli decrease by 63% and 84%, respectively, due to the addition of 0.15 M sodium chloride.…”

Section: Solute Back-diffusionmentioning

confidence: 99%

Unpacking compaction: Effect of hydraulic pressure on alginate fouling

Tow

Lienhard

2017

Journal of Membrane Science

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High hydraulic pressure is often considered to be the cause of the high fouling propensity of reverse osmosis (RO) relative to forward osmosis (FO). Several experimental studies have shown that alginate fouling is more susceptible to cleaning in FO than in RO, but the proposal that foulant compaction causes this disparity seems to be contradicted by the incompressibility of alginate hydrogels. In addition, the effect of hydraulic pressure on fouling in osmotic membrane desalination has never been experimentally isolated, because fixedflux comparisons at different hydraulic pressures require different draw solution osmotic pressures. In this study, a new approach to isolating the effect of hydraulic pressure on alginate fouling and cleaning is introduced: operating FO with elevated but equal feed and draw hydraulic pressures of up to 40 bar. The same concentration of sodium chloride is used as the draw solution in all trials to eliminate possible effects of draw solution composition or osmotic pressure on membrane fouling or cleaning. Theoretical modeling of the effect of alginate foulant compaction on flux reveals that foulant compaction should accelerate flux decline with low salinity feeds but retard flux decline at high salinity. However, in lowsalinity alginate fouling trials, for which foulant compaction should accelerate flux decline, the measured flux decline rate was not affected by hydraulic pressure. Furthermore, when fouled membranes were cleaned by increasing the feed velocity and reducing the draw osmotic pressure, there was no apparent relationship between hydraulic pressure and cleaning effectiveness. Finally, in situ visualization of foulant removal during the cleaning process revealed no difference in foulant removal mechanisms between different hydraulic pressures. These findings demonstrate that alginate gel compaction by high feed hydraulic pressure does not occur and suggest that other explanations should be sought for FO's fouling resistance relative to RO.

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“…For PAO1, it has been shown that OligoG CF-5/20 binds strongly to the surface of the cells and that this causes decreased motility and swarming, a more negatively charged surface and increased aggregation of the bacteria [10]. Furthermore, OligoG CF-5/20 chelates divalent ions with varying efficiency, Ca 2+ binding most efficiently [11]. The ion modulating property of OligoG CF-5/20 could also presumably influence growth of those bacterial strains dependent on divalent ions such as Mg 2+ and Fe 2+ .…”

Section: Oligog Cf-5/20 Is Able To Potentiate the Effect Of Antibiotimentioning

confidence: 99%

Alginate Oligomers Inhibit Growth of Bacteria Causing Bovine Mastitis and Potentiate the Activity of Antibiotics Commonly Used For Treatment of the Disease

Tøndervik¹,

Klinkenberg²,

Aune³

et al. 2017

J Adv Dairy Res

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Alginate oligomers have been shown to disrupt microbial biofilms and reduce minimum inhibitory concentrations (MIC) for many clinically relevant antibiotics to a range of human pathogens. The antibiofilm and potentiating effects of alginate oligomers has previously been focused on bacterial and fungal strains that play significant roles in chronic human infections. This study on the effects of an alginate oligomer (OligoG CF-5/20) on bacteria that cause bovine mastitis is the first report that investigates a significant disease in animal health. The effect of OligoG CF-5/20 on the inhibitory concentrations of ampicillin, erythromycin, cephalothin and lincomycin to a test panel of nine bacterial strains associated with bovine mastitis were investigated. Two different media were used for cultivation, the standard Mueller-Hinton normally used for bacterial MIC determination, and a skimmed milk medium to mimic the native growth conditions for mastitis bacteria. OligoG CF-5/20 was shown to inhibit growth of all strains tested, and demonstrated a 2 to 8 fold reduction in MICs for erythromycin, cephalothin and lincomycin. The data highlights a potential role for alginate oligomers in potentiating the efficacy of antibiotics, and thereby potentially reducing antibiotic use, in the treatment of mastitis in dairy cattle.

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The Effect of Divalent Metals on the Properties of Alginate Solutions. I. Calcium Ions.

Cited by 93 publications

References 0 publications

Rheological Evaluation of Inter-grade and Inter-batch Variability of Sodium Alginate

Rheological Evaluation of Inter-grade and Inter-batch Variability of Sodium Alginate

Unpacking compaction: Effect of hydraulic pressure on alginate fouling

Alginate Oligomers Inhibit Growth of Bacteria Causing Bovine Mastitis and Potentiate the Activity of Antibiotics Commonly Used For Treatment of the Disease

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