Biomedical Engineering Reference
In-Depth Information
Fig. 14
Molecular and schematic models of the designer peptides and of the scaffolds. (
a
) Molecular
models of RADA16, RADA16-Bone Marrow Homing Peptide 1 (BMHP1) and RADA16-Bone
Marrow Homing Peptide 2 (BMHP2). RADA16 is an alternating16-residue peptide with basic
arginine (
blue
), hydrophobic alanine (
white
) and aspartic acid (
red
). These peptides self-assemble
once exposed to physiological pH solutions or salt. The alanines of the RADA16 providing hydro-
phobic interaction are on one side of the peptide, and the arginines and aspartates form comple-
mentary ionic bonds on the other. The BMHP1 and BMHP2 motifs were directly extended from
RADA16 with two glycine spacers and are composed of a lysine (
blue
), serine and threonine
(
green
) and different hydrophobic (
white
) residues. Neutral polar residues are drawn in
green
.
(
b
) Schematic models of several different functional motifs (different
colored bars
) could be
extended from RADA16 (
blue bars
) in order to design different peptides (I, II, III, IV and V). They
can be combined in different ratios. A schematic model of a self-assembling nanofi ber scaffold
with combinatorial motifs carrying different biological functions is shown
self-assembling properties and nanofi ber formations through mixing the modifi ed
peptides with the original RADA16-I. Although their nanofi ber structures appear
to be indistinguishable from the RADA16-I scaffold, the appended functional
motifs signifi cantly infl uenced cell behaviors.
Using the designer self-assembling peptide nanofi ber system, every ingredient of
the scaffold can be defi ned and combined with various functionalities including the
soluble factors. This is in sharp contrast with 2-D systems where cells attach and
spread only on the planar surface; cells residing in a 3-D environment can interact
with their extracellular matrix receptors to functional ligands appended to the pep-
tide scaffolds. It is possible that higher tissue architectures with multiple cell types,
rather than monolayers, could be constructed using these designer 3-D self-assembling
peptide nanofi ber scaffolds.
