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CHAPTER
11Materials forBiomedicalApplications
Biomaterials: Material intended to interface with biological systems to evaluate, treat, augment, or replace any tissue, organ, or function of the bodycf) Biological Materials
Biocompatibility 1. composition of biomaterials2. fabrication process3. implant production
1.1.2 History and Current Status of the Field
Plastics [poly(methylmethacrylate)] to Metal, Ceramic, Polymer
(1)Cardiovascular areaheart valvesynthetic vascular graft
(2) Artificial Joints
(3) Heart-lung machines
blood oxygenation limit blood coagulation problem
(4) Renal dialysis
blood cell lysisinfectionimmune response
1.1.3 Future Directions
inert biomaterialsbioactive materials
smart or instructive materials injectable materialsnano-structured materials
Biomaterials for complete integration
and full reproduction of damaged tissue
1.2 Biological Response to Biomaterials
inflammation, immune response, blood clotting, infection, tumor formation, implant calcification
Factors to be considered for biocompatibility
type of materialsshape of the implantmaterial degradation characteristics surface chemical properties bulk chemical and mechanical properties
the final location and application of the implant
protein and cellular response (in vitro and in vivo)
1.3 Biomaterial Product Testing and FDA Approval
Safe and effective FDA approves devices, not materials
1.4 Types of Biomaterials
1.4.1 Metalsnon-directional metallic bonds with highly mobile electrons
1.4.2 Ceramics non-directional ionic bonds between electron donors and acceptors
--- hard and nondegradable but brittle
1.4.3 Polymers directional covalent bonds
synthetic polymerspolymers from natural sources
1. Elastomers
2. Hydrogels
3. Composite materials
human tissues
1.4.4 Naturally Derived vs. Synthetic Polymers
Naturally Derived Polymers
1. full integration2. easy remodeling 3. limited amount available4. low mechanical properties 5. pathogenic contamination 6. immune response7. biomaterials of decellularized tissue
Synthetic Polymers
1. mass production and sterilization 2. physical, chemical, mechanical, and degradative properties 3. no tissue interaction 4. low healing 5. low chance of human application
1.5 Processing of Biomaterials
(1) surface modification to alter the surface chemical and physicalproperties
(2) shape
1.6 Important Properties of Biomaterials
1.6.1 Degradative properties
undesirable for implantation desirable for certain materials (biodegradable materials)
1.6.2 Surface properties
chemical and physical properties
1.6.3 Bulk properties
(1) mechanical properties : strength and stiffnessanisotropyfatigue property
(2) Physical properties crystallinity thermal transition
(3) Chemical propertieshydrophobicity
1.6.4 Characterization Techniques
Quantitative and Qualitative
1.7 Principles of Chemistry
1.7.1 Atomic structure proton, neutron, electron amu: atomic mass units
1.7.2 Atomic models
electrons: particle-like and wave-like qualities
1.7.3 Atomic Orbitals
Quantum numbers: size, shape, and orientation of the electron probability functions
1. Principal quantum number2. Azimuthal quantum number 3. Magnetic quantum number4. Spin quantum number
(1) Shapes of subshells
(2) Order of subshells and the Aufbau principle
1. Lower energy states filled first 2. Pauli exclusion principle (two electrons with opposite spin) 3. Hund’s rule
1.7.4 Valence Electrons and the Periodic Table
Closed-shell configuration and open-shell configuration Valence electrons: primary bonds like ionic and covalent bonds
1.7.5 Ionic Bonding
Bonding and Force-distance Curves
1.7.6 Covalent Bonding
(1)Atomic orbitals and hybridization
(2) Molecular orbitals
and bonds
(3) Mixed bonds
Ionic bonds ------------- Covalent bonds
1.7.7 Metallic Bonding
Electropositive elements without electronegative elements to accept electrons
Mobile electron cloud or sea Electron sharing but non-directional Mobility of electrons --- conductivity
1.7.8 Secondary Forces
Dipole-dipole interaction
Temporary (fluctuating) dipoles: van der Waals interaction
Permanent dipoles: hydrogen bonds