Biomaterials Flashcards
Biomaterials desirable properties? (10)
Biocompatible Biodegradable Mechanics - strength - toughness - flexibility Sterilisable Non-toxic Surface area Texture & Surface area FBR
Hydrogel advantages (4) & disadvantages (2)?
Ad: Range of chemistries Biocompatible High water content Potentially injectable Dis: Poor mechanical properties Difficult to sterilise
Hydrogel formation?
Physical
Chemical
Alginate & Dextran
Polysaccharides
Injectable, in situ gelling materials
Chitosan
Polysaccharide
Minimal FBR
Bone, cartilage, skin, liver
Cellulose
Polysaccharide
High mechanical & chemical stability
BUT no in vivo biodegradation
Starch
Polysaccharide
Partially degradable bone cements
Hyuluronan
Polysaccharide
stimulates differentiation & proliferation of chondrocytes, bone marrow stromal cells
Soft tissue eng
Collagen (ad/dis)
Protein
Wound dressing, artificial skin
AD: biocom/deg, cell binding, low antigenicity
DIS: low mech strength, risk of viral infection
Elastin
Protein
Excellent properties but complex purification and difficult processing
Polymer synthesis methods?
Addition
Step growth
Ring-opening
Homo vs copolymer?
Homo: higher Tg, slower degradation
Co: lower Tg, faster degradation
Biodegradable definition?
a substance capable of being decomposed by bacteria or other living organisms
Erosion definition?
Loss of mass of materials when degradation products diffuse and dissolve
Bulk erosion vs surface erosion
graphs
Why is degradation faster in vivo?
Faster chain scission via FBR
Faster mass loss from passive & active transport, increased solubility of oligomers due to presence of lipids, mechanical stresses and cellular activity
Ceramic definiton?
A body of crystalline, or partly crystalline, structure which is produced from essentially inorganic, nonmetallic substances and is formed from a molten mass which solidifies on cooling
Glass definition?
Specific form of amorphous inorganic solids that results from very rapid cooling of a viscous molten material to a solid state without crystallising
Glass-ceramic definition?
A slower and controlled cooling down of a glass, partly crystalline and partly glassy
Ceramic microstructure features?
Porosity, grains (boundaries, size, shape, orientation), microcracks
Effect mechanical properties (Hall-Petch)
Ceramic processing
Sintering
Hot pressing
Defects affect final properties!
Ceramic porosity equation
-
Ceramic degradation mechanisms?
Physiochemical, influenced by: - crystalline features (amorphous is faster) - thermodynamic stability - additives Cell-mediated degradation, influenced by: - osteoclasts & macrophages - physiochemical kinetics - surface roughness (rough = faster)
