TECHNICAL TALK
Topic : Biomimetism in biomaterials, the
role of calcium phosphates
Speaker : C. Drouet
Centre Interuniversitaire de Recherche
et d'Ingénierie des Matériaux (CIRIMAT), UMR CNRS 5085,
ENSIACET, INPT.
118 route de
Narbonne, 31077 Toulouse Cedex 4, France
Date/Time :
(Refreshments
will be served at the end of the Seminar).
Venue : LT 9, NTU (Level 4, North Spine,
near SCE)
Abstract:
Biomimetism is a widely used term with many different meanings.
It is generally intended as the imitation of biological systems. This concept
is particularly appealing in the biomaterials field and is frequently invoked
to justify the use of calcium phosphates. However for most applications only a
partial restoration of the biological function is required (essentially related
to basic functions of the tissue) and the imitation of the composition,
structure and microstructure of natural tissues is not necessary. As synthetic
materials are generally unable to fulfil all biological functions, in most
cases the recipient body has to adapt to the presence of a foreign substitute
and its missing or altered biological functions. Two major points have to be
considered: the implant-tissue interface, and the degradation of biomaterials.
The
implant-tissue interface determines the biointegration
of a device and several levels of biointegration can
be achieved from the most primitive fibrous tissue isolation of a foreign body
to the most elaborate direct bonding to the biological tissue. The
implant-tissue interface shall be distinguished from cell-implant interactions
and a good surface for cell adhesion, proliferation and expression might not
necessarily lead to a good tissue-implant interaction.
Biodegradation
raises a different problem especially when biomaterials contain foreign
substances which activate unnatural metabolic
pathways. Even when the residues and metabolites of a biodegration
process are analogous to natural metabolites problems may arise due to uncontrolled
degradation and release. In some biomimetic processes
on the contrary the degradation remains under the control of cell activity and
the materials are able to adapt to different conditions (location of
implantation, individuals). The by-pass of cell control and the spontaneous
degradation of a material always involves a risk even
when substances naturally occurring in the body are involved.
Examples
of different types of biomaterials and body reactions will be given
illustrating the fact that biomaterials even when they
are considered as biomimetic might not be always
suited to the repair processes and/or functional needs of the body.
About
the Speaker
Dr. Drouet has a
Admission is free and all
are welcome. For enquiries, please
contact A/Prof R.V. Ramanujan,