Biomaterial Basics
These are the four requirements of biomaterials covered in lecture: biocompatibility, sterilizability, functionability, and this fourth one, referring to how well a material can be produced.
manufacturability
Of the three metals compared in lecture (titanium, cobalt-chromium, stainless steel), this one is described as having the lowest cost and being the easiest to manufacture.
stainless steel
Lecture describes ceramics as refractory, polycrystalline, hard, wear-resistant, chemically inert, and this one mechanical property that means they "fail without warning."
brittle
This polymer, used in hip/knee bearing liners and inserts, has a very low wear coefficient against metal or ceramic but can trigger osteolysis from wear debris over time.
UHMWPE (ultra-high molecular weight polyethylene)
Lecture defines hydrogels as 3D cross-linked networks of polymers that do this to water/fluids.
__ and __
absorb and retain
This term, defined by the FDA, is "the ability of a material to perform with appropriate host response in a specific situation."
biocompatibility
This mechanical phenomenon occurs when titanium's stiffness causes surrounding bone to weaken from reduced mechanical loading.
stress shielding
Of the three ceramic categories compared in lecture (alumina/zirconia, hydroxyapatite/bioglass, tricalcium phosphate), this one is described as "resorbable" — it fully dissolves and is replaced by new bone.
tricalcium phosphate
This polymer, used in spinal fusion cages and trauma plates, has a modulus close to bone and is radiolucent (invisible on X-ray/CT).
PEEK (polyetheretherketone)
These are the three core components of tissue engineering, according to the lecture diagram: scaffolds, signals, and this third one, defined as cells that can differentiate into different cell types.
stem cells
These are the three sterilization methods listed in lecture for biomaterials.
gamma, gas (ethylene oxide/ETO), and steam autoclaving
This metal is described in lecture as having the "highest wear resistance" and is used for hip/knee bearing surfaces, though it carries a rare risk of ion release with wear.
cobalt-chromium
Hydroxyapatite and bioglass are described as this type of ceramic — one that bonds directly to bone, unlike a bioinert one.
bioactive
In PLA/PGA/PLGA, this is the process by which ester bonds break down into lactic acid and glycolic acid, which then enter the Krebs cycle.
bulk hydrolysis
This term describes transplanting an organ between two different species, such as engineering pig organs for human transplant.
xenotransplantation
These are the two broad classifications of biomaterials shown in lecture — one covering soft and hard tissue, the other covering metals, polymers, ceramics, and composites.
biological and synthetic
This nickel-titanium alloy is classified in lecture as a "smart material" because of its stimuli-responsive, shape-memory behavior.
nitinol
This is the general term for ceramics that show no chemical bond to bone, relying instead on mechanical fit — as with alumina and zirconia in hip/knee bearing surfaces.
bioinert
Between PLA and PGA, this one is stiffer and more crystalline, making it better suited for short-term support like sutures.
PGA (polyglycolic acid)
This is the maximum distance cells can be from a blood supply before they start to die, making vascularization a major tissue engineering challenge.
~200 μm
"Factors Affecting Biocompatibility" diagram splits properties into two categories: bulk material properties (physical/mechanical) and this other category, which includes surface charge, wettability, and corrosion resistance.
__ and __ properties
surface and chemical
This metal, used for temporary fixation like bone plates and screws, is described in lecture as the "least corrosion resistant long-term" of the three metals compared.
stainless steel
This is the surface property of calcium phosphate cements — nanocrystalline and highly this — that promotes protein adsorption and cell attachment, unlike a smooth solid implant.
porous
This is the design variable in PLGA — the ratio between its two monomers — that controls crystallinity, hydrophilicity, and degradation rate.
lactide:glycolide ratio
This tissue engineering technique, shown in lecture with inkjet, laser-assisted, extrusion, and stereolithography methods, builds tissue layer-by-layer using "bioink."
bioprinting