Hydrophobically Modified Gelatin and Its Interaction in Aqueous Solution with Sodium Dodecyl Sulfate

Abstract

The interaction between a series of hydrophobically modified gelatins and the anionic surfactant sodium dodecyl sulfate SDS in a pH ) 6.6/34 mM buffer has been investigated by surface tension, pulsed-gradient spin-echo NMR, viscosity, and small-angle neutron scattering. In the absence of the surfactant, the bulk viscosity of all the gelatins examined here is dependent only on the gelatin concentration and is independent of the number and size of any grafted hydrophobe. Similarly, the small-angle neutron scattering for all samples could be well-described by a two length-scale model. In this model, the smaller dimension represents the local structure of the gelatin molecule and is unaffected by the presence of the hydrophobe(s), while a larger dimension characterizing the network structure increases significantly with the presence of the hydrophobe but not their size. On addition of the anionic surfactant sodium dodecyl sulfate (SDS), the interaction between surfactant and the hydrophobic gelatin with low grafting densities starts at a slightly lower surfactant concentration (CMC(1)) compared with a "blank" material that has no grafted hydrophobe. At higher grafting densities, CMC(1) is greater than the CMC(1) values for the lower grafting density series. For both grafting densities, neither the length nor the number of hydrophobes present has an appreciable effect on CMC(1). There is no change in the amount of SDS bound to the gelatin at saturation. The viscosities of the hydrophobically modified gelatin/SDS solutions do depend on the length of the hydrophobe, albeit rather weakly, but only at the higher grafting density. In summary, the interaction between these gelatin samples and SDS is dominated by the electrostatics of the system; the effects of the hydrophobe are proposed to be largely manifestations of the change in the electrostatic character of the gelatin induced by grafting process, rather than the hydrophobe per se.

Gelatin Coated Hybrid Lipid Nanoparticles for Oral Delivery of Amphotericin B

“…Hence, the pH of the gelatin solution was precisely monitored. The interaction between lipid and polymer was presumed to be due to ionic and hydrophobic interactions, later being among the hydrophobic chains of lipid and that of hydrophobic residues of polymer. − The weaker interactions were further strengthened by cross-linking the gelatin polymer using glutaraldehyde. The formulation prepared without cross-linking was found to be unstable and tended to aggregate upon aging (data not shown), which was in accordance with the results obtained with previous studies .…”

Physicochemistry of hexadecylammonium bromide and its methyl and ethanolic head group analogues in buffered aqueous and gelatin solution

“…Gelatin also forms coacervates with oppositely charged surfactants, and to this end, studies have been mainly made with anionic surfactants. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] Interaction of gelatin with polyanions like sodium polystyrenesulfonate (NaPSS) or sodium poly(2-acrylamido-2-methylpropanesulfonate) 41 or mixed micelles of SDS and a sugar-based non-ionic surfactant 42 have been found to depend on the critical mole fraction, charge density, and chain length of the surfactants. But reports on the interaction of gelatin with non-ionic surfactants 43 or with cationic surfactants of varied types have been strikingly limited.…”

Polymer-Amphiphile Interactions: An Overview

“…Gelatin is a denatured protein and does not interact with surfactants as the folded proteins do [16], it interacts in a simple manner like the polymer. Hydrophobic and electrostatic forces play important role in the interaction of polymers with surfactants when both the components are ionic in nature.…”