Cation-specific vacuum ultraviolet circular dichroism behaviour of alginate solutions, gels and solid films

Liang, Jinghang; Stevens, Eugene S.; Frangou, S.A.; Morris, Edwin R.; Rees, David A.

doi:10.1016/0141-8130(80)90076-8

Cited by 26 publications

(5 citation statements)

References 19 publications

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“…In the Pb-AA complexation experiments, a membranous calcium alginate gel was used as an adsorbent. Liang et al (1980) reported that the primary mechanism of interchain association (gelation) of alginate was by dimerization of polyfuluronate sequences, with specific site binding of calcium ions between alginate chains. This process reached completion at a calcium level of about 30% of the total cation requirement of the alginate.…”

Section: -S a H T -Smentioning

confidence: 99%

Adsorption of Lead Ions on Composite Biopolymer Adsorbent

Seki

Suzuki

1996

Ind. Eng. Chem. Res.

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A fundamental study about the application of biopolymers to the recovery of lead from dilute solution was carried out. A membranous composite biopolymer adsorbent containing two kind of biopolymers, alginic acid (AA) and humic acid (HA), was prepared. HA, which has high solubility in water, was almost completely immobilized in the adsorbent by a combination of calcium alginate gel and activated carbon powder. A general model for complexation between divalent metal ions and acidic sites on biopolymers was applied to explain the adsorption mechanism of lead on the adsorbent (HA−M). The results showed that the complexation constants and the complexation capacities of lead−AA and lead−HA systems were scarcely influenced by immobilization.

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Section: -S a H T -Smentioning

confidence: 99%

Adsorption of Lead Ions on Composite Biopolymer Adsorbent

Seki

Suzuki

1996

Ind. Eng. Chem. Res.

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“…Sodium alginate is a linear copolymer composed of two monomeric units, Dmannuronic acid, and L-guluronic acid and is widely used in pharmaceutical formulations in beads, matrix tablets, microcapsules, etc. Gelation of dilute solutions of sodium alginate occurs in presence of di-and trivalent metal ions by a process involving consecutive guluronic residues in the guluronic acid (G) blocks of the alginate chain (4)(5)(6). When formulated for use in sustained drug delivery, the alginate is usually in the form of a matrix (7,8).…”

Section: Introductionmentioning

confidence: 99%

In Situ Forming Formulation: Development, Evaluation, and Optimization Using 33 Factorial Design

Nagarwal

Srinatha²,

Pandit

2009

AAPS PharmSciTech

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The present investigation concerns with the development and optimization of an in situ forming formulation using 3(3) full factorial design experimentation. Metformin, an antidiabetic drug with upper part of gastrointestinal tract as absorption window was used as a model drug. The formulations were designed with an objective to retain in stomach for an extended time period. The effect of three independent factors--concentrations of sodium alginate (X(1)), gellan gum (X(2)), and metformin (X(3)) on in vitro drug release were used to characterize and optimize the formulation. Five dependent variables-release exponent (Y(1)), dissolution efficiency (Y(2)), drug release at 30 min (Y(3)), 210 min (Y(4)), and 480 min (Y(5)) were considered as optimization factors. The data were statistically analyzed using ANOVA, and a p < 0.05 was considered statistically significant. Three dimensional surface response plots were drawn to evaluate the interaction of independent variables on the chosen dependent variables. Of the prepared 27 formulations, the responses exhibited by batch F17 containing medium level sodium alginate (X(1)), low level gellan (X(2)), and medium level metformin (X(3)) were similar to the predicted responses.

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“…Circular dichroism (CD) spectroscopy has been extensively used to characterise antimicrobial peptides 31 and analyse their interaction with the bacterial cell wall 32 33 . Here CD was used to monitor whether LPS interacts with OligoG CF-5/20 via its carboxyl groups that show intense Cotton effects near 200 and 215 nm 34 . Isothermal titration calorimetry has also previously been employed to elucidate the mechanisms by which novel antimicrobials interact with the cell surface target, LPS 35 36 .…”

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confidence: 99%

The antimicrobial effects of the alginate oligomer OligoG CF-5/20 are independent of direct bacterial cell membrane disruption

Pritchard

Powell

Khan

et al. 2017

Sci Rep

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Concerns about acquisition of antibiotic resistance have led to increasing demand for new antimicrobial therapies. OligoG CF-5/20 is an alginate oligosaccharide previously shown to have antimicrobial and antibiotic potentiating activity. We investigated the structural modification of the bacterial cell wall by OligoG CF-5/20 and its effect on membrane permeability. Binding of OligoG CF-5/20 to the bacterial cell surface was demonstrated in Gram-negative bacteria. Permeability assays revealed that OligoG CF-5/20 had virtually no membrane-perturbing effects. Lipopolysaccharide (LPS) surface charge and aggregation were unaltered in the presence of OligoG CF-5/20. Small angle neutron scattering and circular dichroism spectroscopy showed no substantial change to the structure of LPS in the presence of OligoG CF-5/20, however, isothermal titration calorimetry demonstrated a weak calcium-mediated interaction. Metabolomic analysis confirmed no change in cellular metabolic response to a range of osmolytes when treated with OligoG CF-5/20. This data shows that, although weak interactions occur between LPS and OligoG CF-5/20 in the presence of calcium, the antimicrobial effects of OligoG CF-5/20 are not related to the induction of structural alterations in the LPS or cell permeability. These results suggest a novel mechanism of action that may avoid the common route in acquisition of resistance via LPS structural modification.

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Cation-specific vacuum ultraviolet circular dichroism behaviour of alginate solutions, gels and solid films

Cited by 26 publications

References 19 publications

Adsorption of Lead Ions on Composite Biopolymer Adsorbent

Adsorption of Lead Ions on Composite Biopolymer Adsorbent

In Situ Forming Formulation: Development, Evaluation, and Optimization Using 33 Factorial Design

The antimicrobial effects of the alginate oligomer OligoG CF-5/20 are independent of direct bacterial cell membrane disruption

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