SHS of Porous Biomaterials on TiCoalloys with HAP for the Bone Implants

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SHS of Porous Biomaterials on TiCo-alloys with
HAP for the Bone Implants
Indian Institute of Science Centenary
Celebrations Indo-Russian Workshop
on Self-propagating High Temperature Synthesis
(SHS)

• A.E. Sytschev1, O.K. Kamynina1, S.G. Vadchenko1,
  
• E.N. Balikhina1, E.A. Krylova2, I.G. Plashchina2,
  I.I. Selezneva3, A.N. Konovalov3, A.S.
  Grigoryan4, A.K. Toporkova4
• 1 Institute of Structural Macrokinetics and
  Material Science RAS, Chernogolovka, Russia
• 2 Emanuel Institute of Biochemical Physics RAS,
  Moscow, Russia
• 3 Institute of Theoretical and Experimental
  Biophysics RAS, Puschino, Russia
• 4 Central Research Institute of Stomatology and
  Maxillo-facial Surgery of Federal Agency of
  High-Technology Medical Care, Moscow, Russia

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Task Objective

• Research and development of new mechanically
  strong and porous biocomposites from titanium
  alloys for use as bone bioimplants with
  properties close to those of natural bones.

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Requirements to Bioimplants

• Biochemical and biomechanical compatibility with
  living tissues
• Pore size 100?500 ?m for bone tissue and below
  100 ?m for connective tissue
• Mechanical strength

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SHS Processing of CoTi Porous Scaffolds for Bone
Graft Substitutes

• In cooperation with Dr. Irena Gotman
• Faculty of Materials Engineering, Technion,
  Haifa, Israel

Cobalt instead of Nickel
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Materials

• Fine powders of Co (1-2 µm) from Eurotungsten,
  of Ti (lt10 µm) from Performance Metal and Alloys
  (NJ, U.S.A.) as well as coarse Ti powder (gt100
  µm) from CERAC were used. Homogeneous powder
  Co-Ti blends were prepared by 1h high energy
  attrition milling with 2.5 grinding
  media-to-powder ratio.
• As a foaming additives fine (lt10 µm) titanium
  hydride, TiH2, powder (replacing part of the Ti
  in the blend) or Teflon, C2F4 were used.

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Experimental

• Given the relatively low exothermicity of the
  CoTi?CoTi reaction, Teflon has an advantage of
  adding carbon to the system that can react with
  Ti (TiC?TiC) and hereby increase the combustion
  temperature.

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XRD patterns of porous scaffolds synthesized via
combustion wave mode of SHS from equiatomic blend
of Co and Ti with addition of 4C2F4 as foaming
agent (a) Ti gt 100µm (b) Ti lt 10µm
X-ray Analysis
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SEM micrographs of porous scaffolds produced from
equatomic blends of Co and Ti powders with
addition of C2F4 via combustion wave mode of SHS
(a) and (b) Ti gt 100 µm (c) and (d) Ti lt 10
µm (a), (b) and (c) polished cross section (d)
pore surface.
SEM Analysis
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XRD patterns of scaffold synthesized from
equiatomic blend of Co and Ti (Ti lt 10µm) via
thermal explosion (TE) mode of SHS
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SEM micrographs of porous scaffolds produced from
equiatomic blend of Co and Ti (4TiH2 as a
foaming agent) via thermal explosion mode of SHS
in furnace at 1100ºC (a) polished cross
section (b) pore surface
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Mechanical Properties

• Microhardness (VHN) of the synthesized for all
  starting compositions was in the range 650850
  kg/mm2 (6.58.5 GPa).
• Compression strength, ss, for synthesized porous
  CoTi scaffolds varied from 15 to 40 MPa, being
  higher for specimens with lower porosity.

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Conclusions
All the above experiments demonstrate the
potential of the proposed SHS processing approach
for the synthesis of highly porous intermetallic
CoTi based structures. The results obtained
indicate that the porous bone graft substitutes
synthesized from Co-Ti equiatomic blends of Co-Ti
employing combustion wave propagation mode can be
used in load bearing applications. Corrosion
behaviour of CoTi based porous scaffolds
fabricated employing SHS processing routes in
body fluid should be investigated and compared
with that of Ti and Ti-6Al-4v alloy, which are
used for surgical implants.
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SHS of Porous Biomaterials on TiCo-alloys with HAP

• Calcium Hydroxyapatite
• HAP (Ca10(PO4)6OH2)

HAP has been patented by IBCP and BIOMED Ltd.
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System under study

• Ti Co HAP (Ca10(PO4)6OH2)
• The most popular material for recovery of bone
  tissue is amorphous calcium hydroxyapatite
  Ca10(PO4)6OH2 (HAP). The biocompatibilty of HAP
  grows in the presence of some biopolymers.
  Amorphous HAP HAP biopolymer
• HAP has been patented by IBCP and BIOMED Ltd.

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Examples of SHS-produced materials
(?) (b) (c) (d)
(e) (f)
mm
(?) (Ti Co 10 wt HAPcr) 1 wt TiH2 (b)
(Ti Co 25 wt HAPcr) 1 wt TiH2 (c) (Ti
Co 10 wt HAPorg) 1 wt TiH2 (d) (Ti Co
10 wt HAPam) 1 wt TiH2 (e) (Ti Co) 1 wt
TiH2 (f) (1.25Ti Co 10 wt HAPorg.) 1 wt
TiH2
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Sample Macrostructures
Ti Co 10 wt HAPcr Ti Co 10 wt
HAPorg
Ti Co 10 wt HAPam
Ti Co
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Pore Surface
Ti Co 10 wt HAPcr Ti Co
10 wt HAPorg
Ti Co 10 wt HAPam Ti
Co
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Microstructure of Synthesized Materials
Ti Co 10 wt HAPcr Ti Co 10 wt
HAPorg ? 22 MPa 115 MPa
Ti Co 10 wt HAPam
Ti Co 22.3 MPa
66.5 MPa
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Cytotoxicity Test
Institute of Theoretical and Experimental
Biophysics RAS, Puschino, Russia
Ti Co 10 wt HAPcr Ti Co 10
wt HAPorg
Ti Co 10 wt HAPam Ti
Co
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Cell growth on the Surface of Synthesized
Materials
Ti Co 10 wt HAPcr Ti Co
10 wt HAPorg
Ti Co 10 wt HAPam
Ti Co
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Growth of the Cell Tissue in Pores
Ti Co 10 wt HAPcr
Ti Co 10 wt
HAPorg
Ti Co 10 wt HAPam
Ti Co

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Spread-eagle Cells in the Pores
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The Cell Migration into the Pores
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Experiments in vivo
Central Research Institute of Stomatology and
Maxillo-facial Surgery of Federal Agency of
High-Technology Medical Care, Moscow, Russia
Implants 10 x 0.5 mm discs
Sixteen reproductive he-rats of the Vistar breed
have been operated. Hystological investigation
is in progress.
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Photos of the Capsules (after 20 days)
Very wide and flocculent capsule (40 mm) with
high cellularity (?50)
Wide capsule (24 mm) with lymphomacrophag spots
and vesiculas (?50)
Unfinished wide (20 ??) and flocculent capsule
(?50)
Thin capsule (lt 1 mm) containing a small amount
of cell elements (?50)
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Synthesized Implants
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SUMMARY

• Synthesis conditions (particle size of powders,
  green composition and density, initial
  temperature) for porous Ti?Co?HAP materials have
  been optimized
• The use of amorphous HAP and that doped with
  biopolymers afforded the preparation of
  single-phase materials with a uniform structure
• The materials prepared from the (Ti Co 10 wt
  HAPorg) 1 wt TiH2, (Ti Co 10 wt
  HAPam) 1 wt TiH2, and (Ti Co) 1 wt TiH2
  mixtures were found most suitable for the growth
  of mesenchimal stem cells of human beings
• The best results were obtained for the material
  prepared from the (Ti Co 10 wt HAPorg)
  1 TiH2 mixture

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• THANK YOU
• FOR YOUR ATTENTION !

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The most popular material for recovery of bone
tissue is amorphous calcium hydroxyapatite
Ca10(PO4)6OH2 (HAP). The biocompatibilty of HAP
grows in the presence of some biopolymers.
Amorphous HAP
HAP biopolymer
HAP has been patented by IBCP and BIOMED Ltd.