Biomedical Engineering Reference
In-Depth Information
[18,142]. Polysaccharide-decorated liposomes demonstrated
reduced permeability to water-soluble encapsulated materials and
protection from degradation by lipases [143].
Coating nanoparticles with polysaccharide can be achieved by
adsorption, incorporation, copolymerization, or covalent grafting
[144] and has been reported for many polysaccharides, including
pectin, pullulan, mannan, HA, heparin, chitosan, and dextran [144,
145].
5.5.1 Chitosan-CoatedNanoparticles
The cationic nature of chitosan enables its adherence to mucosal
surfaces. In addition, the ability of chitosan to open tight junctions
between epithelial cells has also been demonstrated [14]. These
characteristics make chitosan appealing as a coating agent of
nanocarriers designed for mucosal delivery. For example, chitosan-
coated poly-ε-caprolactone (PECL) nanoparticles allowed the
bioavailability of the anti-inflammatory drug indomethacin in the
cornea and aqueous humor following topical ocular instillation
[144]. In addition, chitosan coating of liposomes enhanced mucosal
adhesion in rat intestine [146]. The degree of adhesion showed
strong correlation to the amount of chitosan on the surface of the
liposomes. When the chitosan-coated liposomes were used for the
delivery of insulin, the eff ect determined by blood glucose levels was
more significant and longer lasting in comparison with uncoated
liposomes possibly due to mucoadhesion facilitated by the chitosan
coat.
Chitosan coating can be used to replace the cationic polymers
and lipids currently used for nucleic acid delivery thus overcoming
the toxicity, which is the major obstacle in using these compounds.
Chitosan-coated nanoparticles can interact with nucleic acids,
improving the nanoparticle loading efficiency and transfection
properties [144].
Structural benefits of coating nanoparticles with chitosan have
also been demonstrated: Chitosan-coated liposomes were more stable
in stimulated gastric fluids in comparison with uncoated liposomes
[147]. Chitosan-coated PECL nanoparticles also demonstrated
enhanced physical stability [18]. In addition, the chitosan coating
also facilitated the redispersion of lyophilized PECL nanoparticles.
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