Biomedical Engineering Reference
In-Depth Information
(a)
(b)
(c)
(d)
1 mm
1 mm
1 mm
1.27 mm
1.27 m
0 mm
1.27 mm
1.27 m
0 mm
1.27 mm
1.27 m
0 mm
0 mm
0 mm
0 mm
0 mm
0 mm
0 mm
Gel
(e)
(f)
HO
O
O
N
O
NHAc
O
H
O
HO
Beads
O
HO
O
O
1
Cell
Nanofibers
Figure 4.6
3D images of encapsulation of
live Jurkat cells in the presence or absence
of nanofiber 1 and beads. The Jurkat cell en-
capsulation was promoted by the presence
of nanofiber 1 and further facilitated by the
addition of beads which caused even distri-
bution of the nanofiber networks. (A) Jurkat
cells in cell culture medium only; (B) Jurkat
cells in culture medium and in the pres-
ence of nanofiber 1(0.1 wt%); (C) Jurkat cells
in culture medium and in the presence of
both nanofiber 1(0.1 wt%) and beads. The
insets on the top right of the images show
images of the cell culture gel 1. The cells
and nanofibers were pre-labeled with dif-
ferent dyes. (D) Magnified z-slice image of
picture C; (E) The image and the diagram
(not drawn to scale) show how the Jurkat
cells were prepared to encapsulate in cell
culture medium, nanofiber 1(0.1 wt%) in the
presence of beads; (F) Chemical formula of
the gelator composed of nanfiber 1. (Figure
adapted from Ref. [56] (Copyright 2008) John
Wiley & Sons, Inc.)
4.4.3
Lipid-Based Molecular Gels
Lipids are present ubiquitously in the biological system, ranging frombeing a highly
efficient source of energy and major constituents of cellular membranes to various
hormones and signaling molecules required for cellular growth and differentiation
[58]. Due to their prevalence in nature and their inherent biocompatibility and
biostability, lipids have been widely studied and researched by the scientific
community, particularly in drug delivery and tissue engineering. The ability of
lipids, especially those with amphiphilic property, to self-assemble into two- and
three-dimensional supramolecular structures further contributed to their potential
to be used in material science research [59].
Typically, a lipid comprises three essential features, namely a hydrophobic
tail, a polar head, and a backbone that connects the two together [59]. The
polar groups found in lipids can be either one or more charge/uncharged polar
moieties, while the hydrophobic portions of lipids comprise either aromatic or
saturated/unsaturated aliphatic side chains. Lipids are further classified into various
subcategories such as phospholipids, isoprenoids, sphingolipids, glycerolipids, and
sterol lipids, according to their backbone structures. One interesting property of
lipids is their ability to self-associate and self-assemble into specific and ordered
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