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11.3 Uniquely Encapsulated Drug/Biopolymer Nanofiber Systems for Drug Delivery 283

PCL crystal

Water diffusion Ion exchange
Swelling of fibers Drug release

Amorphous
region

IBU Ions in water LDH-IBU Ions exchange
Figure 11.5 Schematic showing IBU release process from LDH-IBU/PCL composite fibers.
(Reproduced with permission from Ref. [53]; Copyright 2012 Elsevier.)
were developed to act as a new double container drug delivery system for tunable
drug release property [53]. It shows that LDH nanoparticles have a heteroge-
neous nucleation effect on PCL chain segments, which can induce the LDH–IBU
platelets being wrapped up in the crystalline regions of PCL (Figure 11.5), thus
restricting molecular movements of water and IBU molecules. Similarly, layered
double-hydroxide intercalated with amoxicillin (LDH/AMOX) was successfully
encapsulated at different concentrations into PCL by electrospinning. The release
curves present an initial high-rate drug release period, followed by a second step
in which the release rate is slower, extending for longer time [54].

11.3
Uniquely Encapsulated Drug/Biopolymer Nanofiber Systems for Drug Delivery

Drug release characteristics largely depend on how well the drug is encapsulated
inside a carrier. Owing to the high ionic strength during electrospinning, drug
molecules are easy to locate on the fiber surface, leading to burst-release prob-
lems [55, 56]. Therefore, encapsulation and sustained release of drugs by conven-
tional electrospinning techniques still remain great challenges. Thus, core–shell
structured nanofibers or nanoparticles are developed by coaxial electrospinning,
emulsion electrospinning, or electrospray, which aims at protecting the unstable
biological agents from harsh environments and delivering the bioactive molecules
or drugs in a sustained way.

11.3.1
Coaxial Electrospun Drug/Biopolymer Nanofibers

Coaxial electrospinning, as a modification or extension of conventional elec-
trospinning with a major difference in the configuration of spinneret, allows