How hydrophobically modified chitosans are stabilized by biocompatible lipid aggregates.
Nanostructured hydrogels composed by biocompatible molecules are formulated and characterized. They are based on a polymer network formed by hydrophobically modified chitosans (HMCHIT or CnCHIT) in which vesicles of monoolein (MO) and oleic acid or sodium oleate (NaO), depending on pH, are embedded. The best conditions for gel formation, in terms of pH, length of the hydrophobic moieties of chitosan, and weight proportion among the three components were estimated by visual inspection of a large number of samples. Among all possible combinations, the system C12CHIT-MO-NaO in the weight proportion (1:1:1) is optimal for the formation of a well-structured gel-like system, which is also confirmed by rheological experiments. Electron paramagnetic resonance (EPR) measurements unambiguously show the presence of lipid bilayers in this mixture, indicating that MO-NaO vesicles are stabilized by C12CHIT even at acid pH. A wide small angle neutron scattering investigation performed on several ternary systems of general formula CnCHIT-MO-NaO shows that the length of the hydrophobic tail Cn is a crucial parameter in stabilizing the polymer network in which lipid vesicles are embedded. Structural parameters for the vesicles are determined by using a multilamellar model that admits the possibility of displacement of the center of each shell. The number of shells tends to be reduced by increasing the polymer content. The thickness and the distance between consecutive lamellae are not influenced by either the polymer or MO-NaO concentration. The hydrogel presented in this work, being fully biocompatible and nanostructured, is well-suited for possible application in drug delivery.
Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106-5080, United States.
Nino
N
Ruocco
Jülich Centre for Neutron Science, JCNS at MLZ, Forschungszentrum Jülich GmbH, 85747 Garching, Germany.
Henrich
H
Frielinghaus
Department of Chemical, Materials and Production Engineering, University of Naples "Federico II", Piazzale Tecchio 80, 80125 Naples, Italy; CSGI, Consorzio interuniversitario per lo sviluppo dei Sistemi a Grande Interfase, Florence, Italy.
Giuseppe
G
Vitiello
Department of Chemical Sciences, University of Naples "Federico II", Complesso di, Monte S. Angelo, via Cintia, 80126 Naples, Italy; CSGI, Consorzio interuniversitario per lo sviluppo dei Sistemi a Grande Interfase, Florence, Italy.
Gerardino
G
D'Errico
Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106-5080, United States.
Leslie G
LG
Leal
Jülich Centre for Neutron Science, JCNS-1, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; Jülich Centre for Neutron Science, JCNS at MLZ, Forschungszentrum Jülich GmbH, 85747 Garching, Germany.
Dieter
D
Richter
Department of Chemical Sciences, University of Naples "Federico II", Complesso di, Monte S. Angelo, via Cintia, 80126 Naples, Italy; CSGI, Consorzio interuniversitario per lo sviluppo dei Sistemi a Grande Interfase, Florence, Italy.
Ornella
O
Ortona
Department of Chemical Sciences, University of Naples "Federico II", Complesso di, Monte S. Angelo, via Cintia, 80126 Naples, Italy; CSGI, Consorzio interuniversitario per lo sviluppo dei Sistemi a Grande Interfase, Florence, Italy. Electronic address: luigi.paduano@unina.it.
Luigi
L
Paduano
D048271:Chitosan / Q000737:chemistry*; D016503:Drug Delivery Systems; D005989:Glycerides / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D019301:Oleic Acid / Q000737:chemistry; D012212:Rheology
D005989:Glycerides; D020100:Hydrogels; D008051:Lipid Bilayers; D019301:Oleic Acid; C013173:osteum; D048271:Chitosan; C005953:monoolein
Hydrogels; Hydrophobically modified chitosans; Olein–sodium oleate; Rheology; Structural characterization