Chitosan Derivatives - Chitosan Based Hydrogels: Functions and Applications - page 49

TAble 2.1
Applications of Acyl-Chitosan Derivatives

Application References

Drug delivery (hydrophobic and hydrophilic drugs) [34-46]

DNA delivery [47-49]

Polymeric surfactants, foaming forming agents [50]

Artificial viscosifiers (biomedical and pharmaceutical application) [50]

Dispersant/coating of nanoparticles (biolabeling and biosensoring) [51,52]

Antibacterial activity (biomedicine) [47]

Smart materials [53-56]

Tissue engineering [38]

One-step purification of IgG [57]

LB layers [58,59]

2.4.1.1 Acyl Derivatives from Anhydrides

N -Succinyl-chitosan (NSCS), with a well-designed structure and the ability to self-assemble
in regular nanosphere morphology, has been successfully synthesized [78]. The in vitro cell
culture indicates that NSCS is nontoxic and has cell compatibility. The interactions between
NSCS and bovine serum albumin (BSA) were studied [34]. It has been demonstrated that
BSA binds to NSCS with a molar ratio of 30:1. This study demonstrates the potential of the
NSCS matrix for encapsulation of proteins or other hydrophilic bioactive drugs.
Stearoyl, palmitoyl, and octanoyl chitosan derivatives with DSs from 0.9% to 29.6% have
been prepared [79]. The N-fatty acylations were carried out by reacting carboxylic anhy-
dride with chitosan in dimethylsulfoxide (DMSO). The chitosan derivative-based micelles
were spherical in shape, their sizes being in the range of 140-278 nm. The properties of
palmitoyl-chitosan micelles such as encapsulation capacity and controlled release ability
of the hydrophobic model drug ibuprofen (Ib) were evaluated [36]. Experimental results
indicated that the loading capacity of palmitoyl-chitosan was approximately 10%. The
drug release strongly depended on pH and temperature; low pH and high-temperature
accelerated drug release markedly.
Chitosan was selectively N-acylated with acetic, propionic, and hexanoic anhydrides
under homogeneous conditions in order to prepare N -acetyl chitosan (NACS), N -propionyl
chitosan (NPCS), and N -hexanoyl chitosan, respectively [47]. NACSs with different
N-acetylation degrees were obtained by controlling the degree of N-acetylation.
Intramolecular aggregation of NPCS and NACS was stronger with NPCS than with NACS.
Hydrophobic interaction of N-acylated chitosan substituted with longer acyl chains was
stronger. With moderate DS, intramolecular aggregation occurs predominantly.

2.4.1.2 Acyl Chitosan Derivatives from Acyl Chlorides

Oleoylchitosans (OCSs) have been synthesized by reacting chitosan with oleoyl chloride
[37]. The hemolysis rates of OCS nanoparticles tested in different conditions were well
within permissible limits (5%). OCS nanoparticles showed no cytotoxicity to mouse embryo
fibroblasts. DOX was efficiently loaded into OCS nanoparticles (encapsulation efficiency:
52.6%). The drug was rapidly and completely released from the nanoparticles (DOX-OCS
nanoparticles) at pH 3.8, whereas at pH 7.4 there was a sustained release after a burst release.