modified natural macromolecules Biomaterials ceramics metals Classes Biomaterials composites synthetic polymers modified natural macromolecules

Biomaterials Materiais Vantagens Desvantagens Aplicações clínicas Polímeros Elasticidade; fácil de preparar; baixa densidade Baixa força mecânica; degradação Suturas; veias; dentes; tendões artificiais Metais Força de tensão elevada; alta resistência ao uso Baixa biocompatibilidadecorrosão em meios fisiológicos; alta densidade Ortopedia (parafusos, placas); implantes dentários Cerâmicos Boa compatibilidade resistência à corrosão; inerte Baixa força de impacto; difícil de fabricar; alta densidade Próteses; dentes Compósitos Cerâmicos revestidos com metal Difícil de fabricar Válvulas artificiais

> 2000 Romans, Chineses, Aztec Biomaterials History > 2000 Romans, Chineses, Aztec Teeth gold Glass eye 20th century Plastics PMMA 1937, Dentistry PMMA 2nd World War Lenses

Resistance to degradation Chemical and Physical Characterization Biomaterials Preparation Choice Biomaterials Biocompatibility Resistance to degradation Chemical and Physical Characterization

Considerations Biomaterials (The effect of the organism on the implant and the effect of the implant on the organism) Considerations 1- The material must not leach or release soluble components into the living system 2- The living systems must not degrade the implant, unless this degradation is intentional 3- Biocompatible 4- Non toxic and non carcinogenic 5- Chemically inert and stable 6- Right mechanical strength 7- Right density 8- Relatively inexpensive, reproducible and easy to fabricate and process on a large scale

Implants Biomaterials Success of Biomaterials or implants is highly dependent on three major factors Properties and biocompatibility of the implant Condition of the recipient Competency of the surgeon who implants

Ideal Biomaterial Biomaterials Must NOT cause Thrombosis Alteration of plasma proteins Destruction of enzymes Adverse immune responses Damage to adjacent tissues Cancer Toxic or allergic reactions

Sterilization Biomaterials Steam (15-30 minutes at 121ºC) Ethylene oxide (48 hours at 30-50ºC) Radiation (UV or Co – 25KGy) Electron beam (25KGy) Dry heat (> 140ºC) New technologies (ClO2, plasma, ozone, X-ray)

Biomaterials Characterization Chemical Physical Biocompatibility “in vivo” “in vitro” Surface characterization

Applications Biomaterials Orthopedy Ophtalmology Dentistry Cosmetic Cardiology

Biomaterials Cardiology Stent

Biomaterials Stent application

Biomaterials Heart valves

Improve blood compatibility Biomaterials Improve blood compatibility Protect the body from the device Surface Modification Increase or decrease wettability of the surface Reduce (or increase) tissue adhesion Protect the device from the body Add biologically active substances to the surface layer Modify the appearance Alter the protein adsortion characteristics

Biopolymers Biostable Polymers Biodegradable Polymers Chemically and mechanically stable in biological medium for extended period of time, which is desired for long term applications – hip implant Biodegradable Polymers Which are required during limited time period – drug delivery system

Biomedical Applications of Polymeric Materials Biopolymers Biomedical Applications of Polymeric Materials Medical - Surgical Applications - Syringes - Bandages - Sutures, etc... Systems with therapeutic function - Drug delivery systems - Diagnostics: Biosensors

Biopolymers Systems to Replace or Assist Malfunctioning Body Parts - Contact lenses - Artificial teeth - Insulin pumps - Artificial kidney - Artificial heart - Orthopeadic protheses - Cardiovascular implants

Biomedical Applications of Synthetic Polymers Biopolymers Biomedical Applications of Synthetic Polymers Orthopaedics (18%) Dialysis (6%) Ophthalmic (4%) Surgery (3%) Dental (2%) Cardiology (26%) Controlled drug delivery systems (25%)

Methacrylic and Acrylic Polymers Biopolymers Methacrylic and Acrylic Polymers CH2 CH COOH CH2 C CH3 COOH acrylic acid - Contact lenses - Bone cements - Dental implants methacrylic acid

Composition of Bone Cement Biopolymers Composition of Bone Cement

Preparation of the Cement Biopolymers Preparation of the Cement

Biopolymers Hip Joint PMMA Metal PE

Biopolymers Poly(urethanes) OCN – diisocyanate – N – C – O - polyether – O – C – N – diisocyanate - NCO H O O H Artificial hearts Blood bags Catheters Heart valves Pacemaker leads Tubing for grafts Ligament replacements

Some Biodegradable Polymeric Biomaterials Biopolymers Some Biodegradable Polymeric Biomaterials

poly(dimethylsiloxane) Biopolymers Silicone Polymers ( ) CH3 Si O n Plastic surgical materials Breast implants Adhesives Heart valves Oxygenators Contact lenses Catheters Blood pumps poly(dimethylsiloxane)

Biomaterials Hydrogels

Hydrogels Biomaterials Background Hydrogels are water-swollen, cross-linked polymeric structures produced by the simple reaction of one or more monomers or by association bonds such as hydrogen bonds and strong van der Waals interactions between chains. The title of my presentation is “Biocatalytic Hydrogels” and reports the work that I have doing during my PhD project under supervision of Prof. Helena Gil and Prof. Jontahan Dordick in the Chemical Engineering Department of Coimbra University and Rensselear Polytechnic Institute. What is hydrogels ? Basically Hydrogels are three-dimensional polymer network that do not disolve in water but are able to swell and retain a significant amount of water. There are several applications for hydrogels such as ... But the physical properties of gels make them attractive for a variety of biomedical and pharmaceutical applications such as... We are mainly interested to use hydrogels for biomedical purposes such as networks to grow cells for tissue enginnering and small solutes and protein controlled-release systems.

Hydrogels Biomaterials Applications: Biotechnology and material fields: super-absorbent diapers; water-treatment additives; membranes for separating biological compounds such as proteins; matrix for affinity chromatography and gel electrophoresis.

Hydrogels Biomaterials Applications: Biomedical field: contact lenses; synthetic joint cartilage; matrix in bone surgery; networks to grow cells for tissue enginnering; small solutes and protein controlled-release systems.

Applications Biomaterials Hydrogels as drug delivery systems and scaffolds for tissue engineering Small drugs, Proteins, Growth factors, Plasmid DNA Cell-adhesion factors Cells

Biomaterials They perform very well when implanted sub-cutaneously, intramuscularly or peritonealy. This is confirmed by implantation studies up to one year duration on various types of animals.

Advantages of hydrogels as Biomaterials Permeable for aqueous solids Permeable to body fluids Soft when hydrated Low adherance to tissue and mucuous membranes Water absorption , swelling Permeable for drug solutions

Hydrogels cathegories by Biomaterials Hydrogels cathegories by origin Natural Synthetic water content Low swelling (20-50%) Medium swelling (50-90%) High swelling (90-99,5%) Super-absorbent (>99,5%)

Hydrogels cathegories by Biomaterials Hydrogels cathegories by processing Thermoset (covalently crosslinked) Thermoplastic (physicaly cross-linked, solid meltable) chemical stability Biodegradable Bioerodible Non-degradable

Essential structure features of hydrogels Biomaterials Essential structure features of hydrogels Polymer chain of hydrophilic units with a broad range of chemical structure but forming strong H-bonds with water Hydrophilic chains tied together by multiple links of covalent or physical nature but stable in presence of water