ISSN : 0975-9492


Open Access

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Title : Hydrophobic Ion-Pairing of Low Molecular Weight Heparin with CetyltrimethylammoniumBromide
Authors : Nermin E. Eleraky, Dina F. Mohamed, Mohamed A. Attia, Giovanni M. Pauletti
Keywords : association complex, stoichiometry, Job’s method, Benesi-Hildebrand plot, Scatchard plot
Issue Date : March 2015
Abstract :
Purpose: Unfavorable physicochemical properties of low molecular weight heparin (LMWH) restrict membrane permeation of this therapeutic macromolecule to paracellular passive diffusion. To augment LMWH flux across biological membranes using contributions of transcellular transport mechanisms, this study explored formation of electrostatically stabilized association complexes via ion-pairing with the lipophilic cetyltrimethylammonium bromide (CTAB). Methods: LMWH/CTAB interactions were assessed in acetate buffer, pH 5.0, using molar ratios ranging from 1:0 to1:40. Unbound LMWH was quantified spectrophotometrically at ?=630 nm using the Azure A assay. Dynamic laser light scattering technology was applied to estimate hydrodynamic diameter and zeta potential of electrostatically stabilized LMWH/CTAB association complexes. Results: Unbound LMWH concentrations significantly decreased from 95.9±2.3% to 14.4±2.6% in the presence of CTAB at a molar ratio of at least 1:30. In parallel, formation of colloidal association complexes was detected exhibiting mean hydrodynamic diameters between 400-500 nm and maximum zeta potential values of +1.85±0.80 mV. Using Job’s continuous variation method, a 1:1 stoichiometry of LMWH/CTAB association complexes in acetate buffer, pH 5.0, was concluded. Benesi-Hildebrand and Scatchard transformations of experimental binding data revealed an estimated formation constant for LMWH/CTAB complexes at pH 5 of 1.1×10-7 and 1.2×10-7L×mol-1, respectively. Conclusion: The results from this study suggest weak ion-pairing between LMWH and CTAB in acetate buffer, pH 5.0. The slightly positively charged nanocomplex is predicted to access transcellular transport mechanisms more effectively than the highly negatively charged LMWH. As a consequence, electrostatically stabilized LMWH/CTAB association complexes may enhance overall permeation properties of LMWH across biological membranes.
Page(s) : 558-565
ISSN : 0975-9492
Source : Vol. 6, No.3