Physico-chemical and structural properties of hydrogels formed by chitosan, in the presence and absence of poly(vinylpyrrolidone) and sodium decylsulfate

Abstract

The structure of chemically-crosslinked chitosan and chitosan-poly(vinylpyrrolidone) (PVP) hydrogels is investigated by means of the combined use of small-angle neutron scattering (SANS), electron paramagnetic resonance spectroscopy (EPR), intradiffusion, and swelling degree measurements. These hydrogels may be described in terms of an inhomogeneous structure composed by polymer-rich and polymer-poor regions. The polymer-rich regions, whose correlation distance zeta is ranged between approximately 600 and approximately 850 A, are, in turn, characterized by the presence of a network formed by the chemical crosslinks, with a mean correlation distance xi approximately 90 A. The structures of chitosan and chitosan-PVP hydrogels have also been analyzed in the presence of sodium decylsulfate micelles that could provide a multidomain system useful, in principle, for drug delivery applications. Both SANS and EPR measurements show that sodium decylsulfate micelles do not significantly interact with both the gels. Finally, intradiffusion and swelling degree measurements show an improved hydrophilicity of chitosan-PVP gels, even further magnified by the presence of C10OS surfactant.

Self-Diffusion in Chitosan Networks: From a Gel−Gel Method to Fluorescence Recovery after Photobleaching by Fringe Pattern

“…The values for 1.5 wt % chitosan gel are ξ = 549 ± 44 Å (pH = 5) and ξ = 616 ± 84 Å (pH = 4). These values are in reasonable agreement with those obtained by G. Mangiapia and co-workers who have investigated the structure of chemically cross-linked chitosan by means of the combined use of small-angle neutron scattering (SANS), electron paramagnetic resonance spectroscopy (EPR), intradiffusion, and swelling degree measurements. These authors have demonstrated that these hydrogels may be described in terms of an inhomogeneous structure composed by polymer-rich and polymer-poor regions.…”

Molecular level and microstructural characterisation of thermally sensitive chitosan hydrogels

“…The correlation lengths, x, are within the range for chitosan hydrogels determined in other studies. 36,52 As a guide, the length of a chitosan monomer is $5.5 A ˚,53 which implies that a length of 115-135 A ˚is equivalent to segment of chitosan chain composed of $21 to 25 monomers. The x increases with increasing chitosan concentration, which may be because the larger number of polymer chains decreases mobility and rotation of each bond within a chain.…”

“…The structure of a chitosan-poly(vinylpyrrolidine) (PVP) hydrogel with potential for a drug delivery system has been reported. 36 The structure is described in terms of a polymer-rich region (characteristic length $600 to 850 A ˚) comprising a network with correlation length $90 A ˚(see eqn (3) and (4) for definition of characteristic and correlation length). The structure of a chitosan-GP hydrogel has recently been investigated on the micron length scale by laser scanning confocal microscopy (LSCM).…”

Viscometric Properties of Carboxymethylchitosan Solutions

“…In order to overcome the water-insolubility and extend its applications, a number of water-soluble chitosan derivatives have been studied. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] The investigations indicated that some chitosan derivatives, such as (2-hydroxyl-3-dodecanoxyl) propyl-carboxymethylchitosan (HDP-CMCHS), (2-hydroxypropyl-3-butoxy) propyl-succinylchitosan (HBP-SCCHS), and (2-hydroxyl-3-butoxyl) propyl carboxymethyl-chitosan (HBP-CMCHS) are soluble, have good interfacial activity and form aggregates in concentrated solutions, contributing to their utilization in drug delivery. [12][13][14][15] In addition, HBP-CMCHS and carboxymethylchitosan (CMCHS) have been used in controlling the crystallization of CaCO 3 via the strong electrostatic interaction between the CMCHS -COO − groups and Ca 2+ ions, permitting the dispersion in aqueous solutions of the resulting CaCO 3 particles.…”