ElectrophoreticElectrophoretic deposition of deposition of

composite materials for biomedical composite materials for biomedical applicationsapplications

Rong MaSupervisor: Dr. Igor Supervisor: Dr. Igor ZhitomirskyZhitomirsky

MATLS 701 Seminar

2

OutlineOutline

•

Introduction

•

Literature review

•

Experimental techniques

•

Objectives

•

Approach and methodology

•

Results and discussion

•

Summary

3

Introduction

Materials for biomedical applications•

Metals

Stainless steel, Ti and Ti alloys•

Ceramics

Alumina, calcium phosphates, zirconia, titania, silica

•

Synthetic polymersPolypyrrole, poly(methyl methacrylate), polyetheretherketone

•

Natural polymersChitosan, alginate, hyaluronic acid

Titanium alloys

Alumina

PEEK-Optima®

Cells alginate microspheres

4

Toxic material The surrounding tissue dies

Bioinert material A fibrous tissue forms

Bioactive material An interfacial bond forms

Bioresorbable material The surrounding tissue replaces it

Implant-tissue response

Metals and alloysFavourable mechanical properties

Corrosion, allergic potential

Bioceramics

and polymersBiocompatible, bioactiveInsufficient mechanical strength

Surface modification

Combine

Ideal bulk propertiese.g. tensile strength or stiffness

Surface propertiese.g. biocompatibility, bioactivity

antimicrobial properties

5

IntroductionBone structureBone structure

Multi-layered structure

Protein (Collagen)

Ceramic (Hydroxyapatite)Polysaccharides(Hyaluronic acid)

(E.R. Wise, et al., 2007)

Recent discovery

Complex collagen-fiber-reinforcednanostructure 70 wt% Hydroxyapatite

+ Collagen

Proteins and polysaccharides are important in bone formation, with vital roles in modulating mineral size and crystallinity.

Protein (Collagen)

Ceramic (Hydroxyapatite)Polysaccharides(Hyaluronic acid)

6

Nanostructured

Composite Films

Layer-by-layer assembly Electrodeposition

Deposition time10-20 h 0.5m film 1-2 min

7

Literature reviewLiterature review

Electrophoretic

deposition (EPD)Two steps:1. Charged particles forced to move toward an electrode (electrophoresis)2. Particles coagulate at one of the electrode and form a coherent deposit

Charged particle electrophoresis

Advantages

fast, room temp, low cost, industrially scaleable, no waste, good control over film properties

8

Chit-NH2 + H3 O+

Chit-NH3+ + H2 O

insoluble soluble

Chit-NH3+ + OH-

Chit-NH2 + H2 O

soluble insoluble

Chitosan

Literature reviewLiterature reviewElectrogenerated base

Cathode

High pH2H2 O + 2e- → H2 + 2OH-

Chit-NH3+ Chit-NH2

Natural polysaccharide

9

(300)Peak

(002)PeakComposite film

As-received HA

High pH region

_

Low pH region

Chitosan-HA composite coatings

X. Pang, I. Zhitomirsky, Materials Chemistry and Physics, 94(2005)245

Sketch of arrangement of mineral particles with collagen fibrils in natural bone

Preferred orientation of HA in the Preferred orientation of HA in the coatings as it is in the bonecoatings as it is in the bone

Chitosan-hydroxyapatite

composite

10

Hyaluronic

acid (Hya) coating

AnodeMixed ethanol-water

2H2 O O2 + 4H+ + 4e-

Hya-Hya-H

F. Sun, et al. Surface Engineering,

25(2009)621

Hyaluronic

acid coatings:

Reduce platelet adhesion

Reduce the gliding resistance of tendon implants

Contain drugs for controlled release

Precipitation by cross-linking using chemicals (alkalines, polyepoxy)

But, limited the hyaluronic

acid combined with specific functional biomacromolecules

11

Coatings containing proteins

Protein Denaturation Strong acid or base Organic solvent Heat Radiation Concentrated inorganic salt

Bovine serum albumin (BSA)BSA coating showed reduced bacterialadherence and anti-thrombogenic

properties

Hemoglobin

(Hgb)Enzymatic Activity

MethodsLayer-by-layer assemblySpin coating Pulsed laser deposition… …

Circular dichroism

spectroscopy

α-helical

β-sheet

coilcoil

12

Electrochemical problem related to the deposition of proteins

NH2NH2

NH2

COOH

COOH

HOOC

Protein composed ofamino acid units

pH

+

Cha

rge

0

Isoelectric point( pI )

Electrogenerated acid2H2

O O2

+ 4H+

+ 4e-

Electrogenerated base2H2

O + 2e-

→ H2

+ 2OH-

Low pH+ High pH -

Acidic solution pH<pI

NH3+

OOC-

+

+ ++

+

+

-

- --

-

-

+

+ ++

+

+

-

- --

-

-+

+ ++

+

+

-

- --

-

-+

+ ++

+

+

Basic solution pH>pI

-

- --

-

-

-

- --

-

--

- --

-

--

- --

-

- -

- --

-

-

+

+ ++

+

++

+ ++

+

++

+ ++

+

+ +

+ ++

+

+

CathodeAnode

13

ObjectivesObjectives

•

Development of new electrochemical methods for deposition of composite coatings containing proteins

•

Development of electrochemical method for the deposition of hyaluronic

acid and

its composite materials from aqueous solutions

•

Investigation of deposition kinetics, mechanism, microstructure and properties of the composite coatings

14

Coatings by EPD

Characterization of the coatings

Investigation of deposition yield

Thermogravimetric

and differential thermal analysis

Scanning electron microscopy

Fourier transform infrared spectroscopy

Circular dichroism

spectroscopy

Approach and methodology

15

Results and discussionResults and discussion

Deposition from 0.5g/L

chitosan aqueous solution

containing 0.25g/L BSA

Deposition yield:

M=M= ttSCSCss UU/d/d

((UU==UUappliedapplied voltagevoltage ––UUvoltagevoltage dropdrop ))Decreased Decreased deposition deposition

raterate

Cathodic EPD of chitosan and BSA from aqueous solutions

S

F

S

F

16

Cathodic

EPD of chitosan

and BSA

2000 1800 1600 1400 1200 1000 800 600

T

rans

mitt

ance

(a.u

.)

Wavenumbers (cm-1)

C+B

CHI

BSA

(CHI) 0.5g/L chitosan solution, (BSA) as-received BSA,(C+B) 0.5g/L chitosan solution containing 0.25g/L BSA

Indicate the possibility of EPD of chitosan

coatings containing BSA!

chitosan

Protein

Chit-NH3+ BSAn-

Complex

Fourier transform infrared spectra

17

High pH

Electrogenerated base2H2 O + 2e- → H2 + 2OH-

Acidic solution pH<pI

++

+ +

++

++

+ ++

+

NH3+

++

+ ++

+

NH3+

OOC-

OOC-

Cathode

Proteins co-deposition:

Charge compensated

Became neutralized

Form a complex deposit

Proposed deposition process

18

Anodic EPD of Anodic EPD of hyaluronichyaluronic

acid from acid from aquaousaquaous solutionsolution

Films prepared at constant voltage of 20 V and deposition time of 3 min from aqueous solutions.

Deposition yield:

MM== tSEtSECCss M= tSECs (1-Cs /Cc ) -1

μ

mobility of hyaluronic

acid molecule,

Cs ,Cc concentrations of hyaluronic

acid in

suspension and deposit.

X. Pang, I. Zhitomirsky,Colloid and Interface science 300(2009)323

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Anodic coAnodic co--deposition of deposition of hyaluronichyaluronic acidacid--BSA complex filmBSA complex film

Films prepared from 0.6 g/L HYNa aqueous Solution containing 0.4 g/L BSA

Films prepared from 3 g/L HYNa aqueous solution

Fourier transform infrared spectra

2000 1800 1600 1400 1200 1000 800Wave number (cm-1)

Tra

nsm

ittan

ce (a

.u.)

HYA

BSA

H+B

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Mechanism of Co-deposition hyaluronic acid-BSA complex

Electrogenerated acid2H2

O O2

+ 4H+

+ 4e-

Low pH +

-

- --

-

-

+

+ ++

+

+

+

+ ++

+

+

-

- --

-

-

-

- --

-

-

-

- --

-

-

nBSA

+ mHYNa

→ (nBSA)(mHY-)

+ mNa+

Intra-polymer (soluable)Inter-polymer (phase separation)

S. Xu, et al. Chem.Pharm.Bull., 48(2000)779

(nBSA)(mHY-)

+

+ ++

+

++

+ ++

+

+

Anode

21

BSA maintain its activity

after deposition

200 210 220 230 240 250 260-30

-25

-20

-15

-10

-5

0

5

10

BSA

Elli

ptic

ity1

03 (deg

cm

2 dm

ole-1

)

Wavelength (nm)

Hya-BSA mixed solution

Hya-BSA complex HyNa

Circular dichroism

spectroscopy

mixturemixture

22

Summary

•

Polysaccharides (chitosan, alginate, hyaluronic acid) have been deposited from aqueous solutions

•

Electrophoretic deposition methods have been developed for fabrication of Chit-BSA

,

Alg-BSA, Hya-BSA, Hya-Hgb, composite films

•

Deposition mechanisms have been proposed which paves the way for developing novel coatings, including proteins and enzymes, for biomedical applications

23

Future work•

Electrodeposition

of composite films

containing other proteins and enzymes for application in biomedical implants and biosensors

•

Investigation coatings electrochemical properties and bioactivities

24

Thank you !