Environmental Engineering Reference
In-Depth Information
Chapter 16
Tailored Bio-Polysaccharide Nanomicelles
for Targeted Drug Delivery
Sabyasachi Maiti
Abstract For poorly water-soluble drugs, the dissolution time in the gastrointes-
tinal contents may be longer than the transit time to the intended absorptive sites.
Therefore, dissolution of drugs is quite often the rate-limiting step for drug absorp-
tion. This poses a major challenge for effective oral delivery of poorly soluble
drugs. Recently, polymeric micelles composed of amphiphilic block or grafted
copolymers have shown much advantage in drug delivery systems and attracted
lots of interest due to its solubilization, low toxicity, long circulation, and passive
targeting against tumor. Generally, amphiphilic copolymers can self-assemble to
form nanosized spherical structures (10-200 nm) consisting of hydrophobic inner
core and hydrophilic outer shell in aqueous medium. The hydrophobic cores can be
used to entrap hydrophobic drugs, and release them in a controlled manner at a later
stage, while the hydrophilic shell provides stabilization for the micelles with no
need of additional stabilizers. Furthermore, the hydrophilic shell can be modified to
have desirable properties, such as evading scavenging by the mononuclear phago-
cyte system (MPS) or obtaining active targeting. Natural polysaccharides are
nontoxic, biodegradable, and easily amenable to chemical modifications to have
better materials for drug delivery applications. In most of cases, a number of
synthetic polymers have been investigated for their drug solubilizing capacity,
loading efficiency, improved bioavailability, and targeting efficiency. However,
the reports on natural polymer-based amphiphilic copolymer are limited in the
literature. The purpose of this chapter is to illustrate recent advancements in the
field of polymeric micelles emphasizing tailored bio-polysaccharide based micellar
carrier systems.
