CALCIUM PHOSPHATE BASED BIO-MATERIALS APPLICABLE IN ORTHOPEDIC - - PowerPoint PPT Presentation

CALCIUM PHOSPHATE BASED BIO-MATERIALS APPLICABLE IN ORTHOPEDIC AND DENTAL MEDICINE

• D. Rabadjieva, S. Tepavitcharova, K. Sezanova,
• R. Gergulova, M. Gabrashanska, R. Aleksandrova

Institute of General and Inorganic Chemistry Institute of Experimental Morphology, Pathology and Anthropology Bulgarian Academy of Sciences

Calcium phosphate biomaterials for

• rthopedic and dental medicine

Biological apatite

• Nano-sized
• Poorly crystallized
• Non-stoichiometric hydroxyapatite

Ca5(PO4)3OH

• Including Na, K, Mg, Cl and CO3

Calcium

• rthophosphates

Not toxic Biocompatible

Calcium phosphate biomaterials for

• rthopedic and dental medicine

RELATIONSHIPS SYNTHESIS – STRUCTURE – INTERFACE TRANSITIONS – MECHANICAL PROPERTIES – BIOLOGICAL PROPERTIES DEVELOPMENT

• f biomaterials with

improved physicochemical characteristics, biological adaptivity and activity

• To develop a method for preparation of calcium
• rthophosphate fine powders with composition and

particle size close to the biological apatite

• To modify the composition improving biological

properties of the materials

• To use these fine powders to prepare
• Composite materials with biodegradable polymer

matrices

• Cements or pastes
• To assess new materials by in vitro and in vivo studies

Method for preparation of calcium orthophosphate fine powders

APPROACH

Biomimetic system - SBF (Na+, K+, Mg2+, Ca2+, Cl-, SO4

2-, HCO3

• , HPO4

2-)

Organic molecules – amino acids, hydrogels, surfactants Ion modification - Mg2+ and Zn2+ Thermodynamic modeling for prediction the system behavior, for experimental design and assessment the experimental results

IDEA

Method for preparation of calcium orthophosphate fine powders Calculated saturation indices (SI) of the salts that might be precipitated in the biomimetic systems

SBF-CaCl2-K2HPO4-KOH SBF-CaCl2-K2HPO4-KOH SBF-CaCl2-MgCl2-K2HPO4-KOH SBF-CaCl2-ZnCl2-K2HPO4-KOH

Method for preparation of calcium orthophosphate fine powders SBFc-Cam K2HPO4 SBFc-Pm CaCl2+MgCl2 SBFc-Cam ZnCl2

• Drop-wise precipitation
• Under ammonia/glycine

buffer

• pH 8, room temperature
• Intensive stirring

Method for preparation of calcium orthophosphate fine powders

Method for preparation of calcium orthophosphate fine powders

PRECURSORS

Compositions of the initial precipitated solid phase

1 2 3 4 5 6 7 8 9

2

• th

e ta

• S

c a le

XRD powder data

Mg(Zn)/(Mg+Zn+Ca) = 0, 1, 2, 3, 5, 10, 13, 16 mol % Ca/P = 1.3 – 1.4 Na+ = 0.02-0.08 mmol/g; K+ = 0.01 – 0.02 mmol/g Cl- < 0.05 mmol/g Mg2+ = 0.03 – 0.05 mmol/g

IR spectra

Method for preparation of calcium orthophosphate fine powders

PRECURSORS

rZn2+ - 0.74 Å rMg2+ - 0.65 Å Calcium vacancies Са/Р<1.5 partially fill Ca vacancies isomorphic substitution

• f Ca

PO4

3-

rСa2+ – 1.00 Å rNa+ - 0.95 Å rK+– 1.33 Å

Result  CawMgxNayKz(PO4)6-v(CO3)v

SBF CO3

2-, Cl-, SO4 2-, PO4 3-

Na+, K+, Mg2+, Zn2+, Ca2+ Posner clusters - Ca9(PO4)6.nH2O

Method for preparation of calcium orthophosphate fine powders

PRECURSORS RELATIONS

Prepared in ammonia buffer Prepared in glycine buffer and hydrogel of xanthan gum Prepared in presence of surfactant PEG 7

Method for preparation of calcium orthophosphate fine powders

PRECURSORS RELATIONS

Synthesis (Ca+Mg+ Zn)/P Zn/(Ca+ Mg+Zn) Mg/(Ca+ Mg+Zn) SSA, m2/g Initial 3.00 14.00 Ammonia buffer 1.59 2.95 4.65 34 Glycine buffer 1.54 2.85 8.50 28 Glycine buffer in a presents PEG-7 1.59 2.90 8.23 30 Glycine buffer in a presents Xanthan gum 1.40 1.74 13.68 32

PHASE TRANSITIONS Low temperature - precursors maturation

Phase *Precipita tion МАP SAP SBFc SBFr SBFcg SBFc SBFr SBFcg Mg3(PO4)2:8H2O 0.2

• 2.84
• 2.38
• 2.43
• 6.58
• 3.88
• 5.57

CaCO3 1.46

• 0.6
• 0.82
• 2.87
• 1.75
• 2.74

CaHPO4:2H2O 2.7

• 0.75
• 0.67
• 0.6
• 1.25
• 1.78
• 1.39

Ca3(PO4)2(am2) 9.94

• 4.18
• 4.45
• 4.25

Ca4H(PO4)3:2.5H2O 13.69

• 4.22
• 5.01
• 4.44

Ca9MgH(PO4)7 16.43

• 5.41
• 5.49
• 5.4

Ca5(PO4)3(OH) 24.06

Calculated saturation indices (SI)

PHASE TRANSITIONS Low temperature - precursors maturation

SBF

• SBFc (HCO3 – 4 mmol/l)

SBFr (HCO3 – 27 mmol/l) SBFg (~SBFc + Glycine)

• 37oC, pH 7.3;
• Static regime; Solid/liquid ratio 4 g/l ;
• Duration – 1, 2, 4, 6, 24 h, 3, 10 days,

1 month;

• SBF solution changes - after 3-rd day

PHASE TRANSITIONS Low temperature - precursors maturation

10 20 30 40 50 60 70 80 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

SBFc SBFr SBFg PO4

time, h

10 20 30 40 50 60 70 80 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50

Ca

2+, mmol/l

time,h SBFc SBFr SBFg

10 20 30 40 50 60 70 80 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

time,h Mg

SBFc SBFr SBFg

KINETIC STUDIES Kinetic profile of PO4

3-, Ca2+ and Mg2+ contents in liquid

phases after different maturation times

PO4

3-

Ca2+ Mg2+

SBFg

002 300

2-theta-Scale initial

SBFc SBFr

10 20 30 40 50 60 10 20 30 40 50 60 10 20 30 40 50 60

1h 2h 4h 720h

002 300 002 300

PHASE TRANSITIONS Low temperature - precursors maturation XRD STUDIES XRD powder data of solid phases after different maturation times

Calcination at 600oC PHASE TRANSITIONS High temperatures

20 30 40

HA + TCP

Zn-TCP

P0 Zn1 Zn3 Zn 5 Zn10 Zn13

Zn-TCP

2-theta-scale

20 30 40

Mg-TCP HA + TCP HA + Mg-TCP 2-theta-scale

Mg0 Mg2 Mg5 Mg10 Mg16

Calcination at 800 and 1000oC PHASE TRANSITIONS High temperatures

PHASE TRANSITIONS High temperatures Mg/Zn-ACP mixed crystals

rMg2+, rZn2+ < rCa2+

unit cell distortion volume decrease Destabilization of Hydroxiapatite structure Mg/Zn-(-TCP)

PHASE TRANSITIONS High temperatures

CaOn coordination polyhedrons (n=3,6,7,8) -TCP substitution in CaOn n =3, 6 most suitable isomorphic substitution substitution in CaOn n =7,8 strong distortion -TCP

Method for preparation of calcium orthophosphate fine powders

Precursor precipitation Calcination Suspension gelling and liophilization Heating at 300oC and washing Second gelling and liophilization

Method for preparation of calcium orthophosphate fine powders Effect of ion modified calcium phosphate materials on viability and proliferation of human Lep 3 cells (MTT,72h)

Method for preparation of calcium orthophosphate fine powders

Zn-β-TCP, on the 14th week following intramuscular implantation as a paste: a) Small fragments of the Zn-β-TCP samples are encapsulated by a fibrous capsule (FC) and are separated by ingrown connective tissue. There is no lymphoid hyperplasia within a regional popliteal lymph node (PLN). b) Slight foreign body reaction including giant cells (GC) and macrophages. c) Ingrown new blood vessels (Vsc) within the newly formed connective tissue. A paraffin section stained with hematoxylin eosin.

Composite materials with biodegradable polymer matrices Calcium phosphate fine powders Hydrogels Gelatin Xanthan gum Carrageenan Saccharose

Composite materials with biodegradable polymer matrices Test in model bone system and Simulated Body Fluid

SEM images before and after 1 month in SBF

Composite materials with biodegradable polymer matrices Effect of composite scaffolds

• n the viability and

proliferation of rat bone marrow cells

control cultivated for 6 days in the presence of composite scaffolds

Acknowledgments

This work was financially supported by the Bulgarian Ministry of Education and Science under Project DFNI T02-5/2014.