Biological Properties ISSUES TO ADDRESS... Biomaterials definition Different types of interaction between body and foreign material What are main characteristics.

Biological Properties

ISSUES TO ADDRESS...

•Biomaterials definition

•Different types of interaction between body and foreign material

•What are main characteristics of a biomaterial

•Types of biomaterials

•Applications of biomaterials

Biomaterials Definition• A multidisciplinary knowledge of studying materials

behavior in the body environment• Any material, natural or synthetic, that comprises

whole or part of a living structure or a biomedical device which performs, enhances, or replace a function that has been lost through disease or injury

Different types of interaction between body and foreign material

Type of foreign materialResultExample

ToxicTissues deathMost of the Metals

Nearly InertFibrous tissue formationMost of the Ceramics like Alumina and Zirconia

BioactiveSurface-tissue interaction at the interface

Hydroxyapatite, Bioglass

DegradableSubstitution of material whit tissue

Tricalcium phosphate, Collagen

What are main characteristics of a biomaterial?

• Biocompatibility• Mechanical properties• Properties regarding to application

Different types of biomaterials

PropertyMetalPolymerCeramic

BiocompatibilityLow

Toxic productsIntermediateCan be toxic

HighMostly bioactive

and non-toxic

MechanicalHigh intermediateLow

ProcessabilityintermediateHigh Low

Classification of application of materials in Biomedical Engineering

• Implants and tissue replacement• Tissue Engineering• Drug delivery systems• Biosensors and medical diagnosis

Implants and tissue replacement

Body Biomaterial

Fibrosis encapsulation Protein attachment Coagulation Mechanical degradation and erosion Undesirable immunological response Biomaterial rejection

BiocompatibilityBiocompatibility is the ability of the materials to

perform in the presence of an appropriate host for a specific application.

Titanium and titanium alloys (Thin surface oxide)Relatively inert good corrosion resistance

Cardiovascular substitutes:Artificial heart valves

• Heart Function : pumping blood to all parts of body• Entrance and outgoing of blood into ventricle heart

is occurring in heart valves

-Tricuspid valve - Pulmonary valve - Mitral valve- Aortic valve

Types of Artificial Heart Valves Natural substitutes(Bioprosthetic Heart Valves)- High biocompatibility and blood compability - Shorter life-time- Grafting problems like out break of disease

Artificial substitutes(Mechanical Heart Valves)- Longer life-time- Stronger mechanical properties- Can be lead to coagulation

Skin Tissue Engineering

Nerve repair

Injectable Scaffolds (Insitu forming)

Cell Source

1. Autologous cells2. Allogenic cells

• Primary cells• Cell-Lines• Stem cells

Stem cells

Drug Delivery Systems• Delivering drug or any other biological agent to a specific part of patients

body with the control of the dosage• Advantages:

– Increasing drugs effectiveness– Preventing from toxic dosages– Decreasing side effects– Preventing drug loss– Controlling drug behavior– Probability of targeted and prolonged release

Biosensors

• The term ‘‘biosensor’’ is used to cover sensor devices in order to determine the concentration of substances and other analytes of biological interest, in some cases even where they do not utilize a biological system directly

Biosensors

Biosensors

• Sensors compared with sense organs of man: - Optical sensors- eyesight - Gas sensors- olfaction - Sensors for pressure, temperature-touch - Acoustic sensors- hearing - Chemical sensors- taste

Materials for biosensors

Piezoelectric Sensors

Bioceramics

• Calcium phosphates: hydroxyapatite, tricalcium phosphate

• Alumina• Zirconia• Glass-Ceramics• Bioglass• Clays and LDHs( Layered Double Hydroxide)• Ferromagnetic bioceramics• Carbons

Types of bioceramicsFormsStructureapplication

Powder and granules PolycrystallineAmorphous

Filler, tissue regeneration and repair

CoatPolycrystallineAmorphousSemi-Crystal

Tissue bonding, anti-coagulation, anti-corrosion

BodySingle crystalPolycrystalline

AmorphousComposite

Tissue regeneration and replacement

Bioceramics advantages over other materials

• Consisting of elements similar to body physiological environment like: Ca, K, P, Na and Mg

• Products of mechanical degradation and chemical dissolution are inert and can be adsorbed through body metabolism

• Strong ionic and covalent bonds and lack of free electrons prevent formation of electrochemical cell

Types of Bioceramics

• Nearly Inert• Bioactive• Resorbable• Porous

Bioceramics applications

• Orthopedic implants• Dental implants• Grafts and substitutes• Hypodermic devices• Ear implants• Contact lens• Artificial heart valves