(55a) Helical Rosette Nanotubes as a Biomimetic Tissue Engineering Scaffold Material

It is widely known that mimicking the nanometric features of natural tissues in biomaterials is
very useful for improving cell adhesion, proliferation and differentiation.
Helical rosette nanotubes (HRN) are one type of such organic nanomaterials which self-assemble when added to water.
Through non-covalent interactions such as H-bonding, base
stacking interactions
and hydrophobic interactions, the building blocks of HRN when self-assembled
form a stable nanotube with a hollow core 11 Å across. Since the chemical
properties and
nanometric structures of HRN are very similar to those
of collagen and hydroxyapatite
(the nanostructured constituent components in bone),
it is anticipated that HRN would be more
well-suited for orthopaedic applications
compared to conventional implant materials such as titanium which do
not mimic the nanometer features of bone. For this reason, the current study is focused on
investigating HRN as
a potential orthopaedic tissue engineering scaffold. Compared to uncoated titanium,
in vitro studies clearly showed that osteoblasts
(bone-forming cells) adhered more on specialized versions of HRN, specifically
HRN functionalized
with lysine (K) and arginine (Arg) when coated on titanium
surfaces. This
phenomenon may be attributed to the presence of amino acids side chains (such as
arginine and lysine) as well as the
biologically-inspired nanometric features that HRN
form when coated on titanium. Moreover, HRN can undergo a phase transition from
liquid to a viscous gel when heated to 60 °C or when added directly to
serum-free media at body temperatures. Transmission electron microscopy (TEM) showed that a densely-packed nanotube network is formed in the viscous gel. Further in
vitro studies including measuring osteoblast adhesion and subsequent functions when cultured
in the viscous HRN
tissue engineering scaffold will be presented. In this manner, this study
introduces a new self-assembled nanomaterial, HRN, that is showing promising in various orthopaedic tissue engineering applications.