Dr. Kalpana S. Katti
BONE BIOMATERIALS
Bone Replacement Materials: Composites and Tissue Engineering
v Composites
In the quest for new materials
for bone replacement, it is of interest to form new composites with mechanical
properties similar to that of bone to avoid problems such as stress shielding
of surrounding bone that are associated with the currently used coated metallic
bone implants. Bone is primarily composed of the mineral hydroxyapatite and
collagen in addition to water and cells. The unique properties of bone arise
from the role of organics in synthesis of the hydroxyapatite. This molecular
control of crystallization of inorganic phases by organic has shown great
promise for fabrication of new structural composites for several applications.
Recently, attempts at mineralization of synthetic hydroxyapatite in the
presence of organic additives, (insitu mineralization) have shown some
improvement in resulting mechanical properties. However, fundamental
understanding of the role of organic on bulk mechanical properties is lacking.
This understanding will allow design of composites with mechanical properties
tailored for bone replacement. The focus of this research is to investigate means of
controlling mechanical properties in insitu HAP-polymer composites for their
potential use as bone replacement. The major aim of the project is to identify
and determine fundamental molecular interactions between HAP and the chosen
polymeric additives during mineralization of HAP that lead to the resulting
microstructure and bulk mechanical properties. This research involves
experimental work involving synthesis of the composite powder, mechanical
consolidation of powder, mechanical testing of the composite in combination
with spectroscopic characterization.
v Tissue Engineering
Polymeric scaffolds
that can withstand load and also allow bone tissue to grow and generate new
bone is the essence of the bone tissue engineering efforts. Our efforts have
been towards influencing interfacial behavior in composite scaffolds to manipulate
mechanical behavior, and bioactivity.
v Molecular Modeling the polymer-mineral
interface
The molecular interactions in polymer-mineral interfaces
are known to have significant role of mechanical response of the composite
system. We have modeled interactions between such dissimilar molecules using
molecular dynamics (MD). We have obtained the parameters of CVFF (consistent
valence force field) for monoclinic
hydroxyapatite. The MD simulations showed that several hydrogen bonds may form
between HAP and polyacrylic acid depending upon the exposed surface of HAP.
Also there are some favourable planes of HAP where polyacrylic acid is most
likely to attach. We have also simulated the mineralization of HAP using a
“synthetic biomineralization” process. These modeling studies are supported by experimental
studies that include photoacoustic spectroscopy experiments on both porous and
non porous composite samples for potential joint replacement and bone tissue
engineering applications.
v People
v Recent
Publications
.
v D. Verma, K. S. katti, D. R. Katti, B. Mohanty, (2007), "Mechanical response and multilevel structure of biomimetic hydroxyapatite/polygalaacturonic/chitosan nanocomposites", Mater. Sci. Eng. C. in press
v R. Bhowmik, K.S. Katti, and D.R. Katti, (2007) “Molecular Modeling of polyacrylic acid- hydroxyapatite interface” Polymer, 48, 664-674.
v P. Ghosh, D. R. Katti, K. S. Katti, (2007), Mineral proximity influences mechanical response of proteins in biological mineral-protein hybrid system, Biomacromolecules, 8, 851-856.
v
R. Bhowmik K.S. Katti, D. Verma and D.R. Katti, (2007), “Probing Molecular Interactions in Bone Biomaterials: Through Molecular Dynamics and Fourier Transform Infrared Spectroscopy”, Mat. Sci. Eng C
v P. Ghosh, D. R. Katti, K. S. Katti, (2006) “Impact of b -sheet conformations on the mechanical response of protein in biocomposites” Materials and Manufacturing Processes, 21, 676-682.
v K. S. Katti, Phanikumar Turlapati, Devendra Verma, Praveen Kumar Gujjula, Dinesh R. Katti, (2006),“Static and dynamic mechanical behavior of hydroxyapatite-polyacrylic acid composites under simulated body fluid”, American Journal of Biochemistry and Biotechnology, 2 (2), 73-79.
v
D. Verma, K. S. Katti, D. R. Katti, (2006), Bioactivity in Insitu Polycaprolactone-Hydroxyapatite composites”, Journal of Biomedical Materials Research78A, 772-780.
v D. Verma, K. S. Katti, D. R. Katti, (2006), “Molecular Interactions in Hydroxyapatite/Polyacrylic Acid /Polycaprolactone Composites: A Photoacoustic FTIR Spectroscopy Study”, Journal of Biomedical Materials Research A, 77, 59-66.
v K. S. Katti, (2004), “ Biomaterials in total hip replacement,” Colloids and Interfaces B. 39, 133-142.
v Funding
National Science Foundation CAREER Award
