CHAPTER1 Materials for Biomedical Applications Biomaterials: Material intended to interface with biological systems to evaluate, treat, augment, or replace any tissue, organ, or function of the body cf) Biological Materials Biocompatibility 1. composition of biomaterials 2. fabrication process 3. implant production

1.1.2 History and Current Status of the Field Plastics [poly(methylmethacrylate)] to Metal, Ceramic, Polymer (1)Cardiovascular area heart valve synthetic vascular graft

(2) Artificial Joints

(3) Heart-lung machines blood oxygenation limit blood coagulation problem (4) Renal dialysis blood cell lysis infection immune response

1.1.3 Future Directions inert biomaterials bioactive materials smart or instructive materials injectable materials nano-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 materials shape of the implant material 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 Metals non-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 Polymers directional covalent bonds synthetic polymers polymers 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 integration 2. easy remodeling 3. limited amount available 4. low mechanical properties 5. pathogenic contamination 6. immune response 7. 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 physical properties (2) shape 1.6 Important Properties of Biomaterials Degradative properties undesirable for implantation desirable for certain materials (biodegradable materials) Surface properties chemical and physical properties

1.6.3 Bulk properties (1) mechanical properties : strength and stiffness anisotropy fatigue property (2) Physical properties crystallinity thermal transition (3) Chemical properties hydrophobicity Characterization Techniques Quantitative and Qualitative

1.7 Principles of Chemistry Atomic structure proton, neutron, electron amu: atomic mass units 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 number 2.Azimuthal quantum number 3.Magnetic quantum number 4.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