Biomaterial

• The analysis of risks and benefits has to take into account tumourigenity, graft rejection, immunogenity and cell migration
• Applications of Biomaterials

  • Replacement of diseased or damaged tissue
  • Assist in healing
  • Improve function
• Replacement of diseased or damaged tissue


  • Orthopedic implants, heart valve, Hip prosthesis, Knee prosthesis
• Assist in healing


  • Medical glues, hemostatic sponges, sutures, bone plates, orthopedic screws
• Improve function


  • Cardiac stent, pacemaker, orthodontic wire
• Classification of biomaterials based on material source


  • Natural (Autograft, Allograft, Xenograft, Isograft)
  • Synthetic (Metals, ceramics, polymers, semiconductor materials)

  
• Bioinert


  Has minimal interaction with its surrounding tissue, Examples: stainless steel, titanium, alumina
• Bioactive


  Interacts with the surrounding tissue, Examples: hydroxyapatite, glass ceramic
• Bioresorbable


  Dissolved (resorbed) and slowly replaced by advancing tissue (such as bone), Examples: tricalcium phosphate, poly(lactic–co-glycolic acid) copolymers
• Biocompatibility


  Ability of material to obtain an appropriate biological response in a given application in the body
• Metals

  • Superior mechanical properties, Can be prepared in various forms and textures
  • May corrode and release harmful metallic ions, Dense and heavy, Not aesthetic, Not biodegradable
• Corrosion

  Deterioration of a metal, Chemical (non aqueous) corrosion, Electrochemical corrosion
• Titanium and Titanium alloys


  • Good mechanical properties, Corrosion resistance, Adsorption of the proteins on Ti surface, Not toxic, inert, and do not cause chronic inflammatory reactions
• Titanium's corrosion resistance is provided by a tightly adherent TiO2 film through passivation
• Ceramics, glasses, and glass-ceramics


  • Inert and superior biocompatibility, Bioactive, High compressive strength and hard, Aesthetic qualities, Can be injectable
  • Brittle and not flexible, Low tensile strength, Difficult to make and form
• Polymers


  • Resilient, Soft (low friction), Aesthetic, Biodegradable, Easy to manipulate, form, and use, Low cost
  • Low mechanical strength, May deform with time and temperature, Leaching monomers
• Tissue Engineering

  Reconstruct the diseased or damaged tissues
• Tissue Engineering


  1. Remove cells

  2. Expand number in culture

  3. Seed onto an appropriate scaffold with suitable growth factors

  4. Place into culture

  5. Re-implant engineered tissue repair damaged site
• Most tissues cannot regenerate when injured or diseased
• Even tissues that can regenerate spontaneously may not completely regenerate due to large defect and excessive tissue strain
• Replacement of tissue with permanent implants is greatly limited, e.g limited integration, low rate of regeneration
• Which tissue can regenerate


  • Connective tissues, Skin, Bone
  • Articular cartilage, ligament, inter-vertebral discs, Muscle (Smooth, Cardiac, skeletal), Nerve
• Potential cell sources (differentiated or adult stem cells)

  • Autogeneic (autologous) cells
  • Allogeneic cells
  • Xenogeneic cells