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Biomaterials > Midterm exam > Flashcards

Midterm exam Flashcards

1
Q

Anode

A

oxidation: electron generation occurs here

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2
Q

Cathode

A

Reduction: electron consumption occurs here

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3
Q

biocompatibility

A

the ability of a material to perform well with a host

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4
Q

Bioglass

A

glass used in biomaterial applications

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5
Q

Bioactive

A

results in a specific bond formation between tissue and material

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6
Q

Compression molding

A

forming process that forces the material to conform to the mold

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7
Q

crevice corrosion

A

due to chemical environment, intense and localized, accelerated by defects (scratches). Occurs between two regions of same material. Prevented by using welds when possible

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8
Q

die swell

A

partial recovery of a polymer after passing through a die

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9
Q

extrusion

A

pushing or pulling a material through a die to form an object with a fixed cross section

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10
Q

fretting corrosion

A

due to mechanical environment. Removal of passivizing layer. Example:vibration

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11
Q

galvanic series

A

determines the nobility of metals (anodic cathodic)

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12
Q

glass transition temperature

A

the temperature where a polymer changes from a rubbery state to glassy

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13
Q

glassy state

A

a hard and brittle state

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14
Q

hydrogel

A

mostly water, soft and elastic, no flow when in the steady state

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15
Q

inflammation

A

expansion of tissue when there is bad biocompatibility

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16
Q

injection molding

A

processing parts by injecting material into a mold. Usable with many materials

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17
Q

inter-granular corrosion

A

corrosion caused by impurities at the grain boundaries. common for stainless steel. Controlled by proper metal selection, coating, heat treatment, passive oxide layers

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18
Q

interpenetrating network

A

a 3 dimensional network that exists in hydrogels.

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19
Q

passive layer

A

a protective layer usually on metals that passivizes corrosion

20
Q

pitting corrosion

A

takes place in the presence of aggressive anions (ex. chlorides). Damages passive layer at localized spots. Burrows into the metal

21
Q

plastification

A

the process of becoming plastic like

22
Q

powder processing

A

basic processing technique with metals. Results in low ductility, high Tm

23
Q

rubbery state

A

the state when above the glass transition temperature

24
Q

stress corrosion cracking

A

results from combination of mechanical load and mildly corrosive environment. Leads to cracking and failure

25
Q

thermoforming

A

heating a material to make it pliable, then shaping it in a mold.

26
Q

thermoplastic

A

a plastic that isn’t crosslinked and becomes pliable when heated (acrylic, nylon, PLA, PE, PTFE)

27
Q

thermoset

A

crosslinked polymer that is irreversible when cured. (polyurethanes, epoxy resin, polyimides).

28
Q

toxicology

A

concerned with the adverse effects of chemicals on living organisms

29
Q

electrospinning

A

uses an electric charge to make fine fibers

30
Q

In vitro testing alternatives to in vivo ? when should we use in vitro? What are the benefits/drawbacks to in vitro testing?

A

metabolic rates are slower in vitro, there?s lack of circulation, absence of mechanical strain, some cell types are difficult to harvest. Benefit of being cheap to perform, no risk to a host. Should be used whenever possible to avoid risk to host

31
Q

Who defines what types of biocompatibility and efficacy testing is required for a biomaterial?

A

FDA must approve the biomaterial

32
Q

Describe the wound healing response and Inflammatory cascades. Why it is important to understand when designing implants?

A

Inflammatory Phase: vasodilatation, capillary permeability, neutrophil infiltration, cytokine release. Proliferative Phase: 2 weeks post, fibroblast infiltration, collagen synthesis. Remodeling Phase: 3 weeks post injury, can last for years, mature scar formation, collagen resporption & remodeling

33
Q

How does biomaterial wear debris cause implant failure?

A

It can damage the passive layer or cause defects that lead to localized corrosion and eventually failure

34
Q

Be able to describe when a degradable material is desirable versus a nondegradable and vice versa.

A

degradable is desirable for when the material is designed to be temporary (ex. stitches, drug delivery)

35
Q

Classification of bioceramics ? be able to describe in your own words the different properties associated with each.

A

Bioinert: little or no reaction with tissue, but difficult to form bond with tissue. Bioactive: can bond to bone. Biodegradable: low bulk density, excellent biocompatibility.

36
Q

Why are bioceramics considered to be ?bioactive? and ?osteoconductive??

A

They form strong bonds with bone.

37
Q

In your own words describe how hydroxyapatite is used in biomedical applications.

A

It is used in biodegradable ceramics and it?s similar to bone and teeth. It can also be used in ocular implants, drug delivery, and as a space filler (diseased bone loss, excised tumors). Absorption rate impacted by surface area, crystallinity, grain size, ionic substitutions

38
Q

Processing ceramics.

A

powder pressing. attributes also impacted by heat treatments.

39
Q

Polymer processing.

A

thermosets and thermoplastics.

40
Q

Metal processing.

A

alloying, heat treatment, purification, casting, powder processing, cold working

41
Q

Why are traditional fabrication routes often not ideal for processing polymers into useful 3D structures for biomedical applications?

A

they result in surface defects

42
Q

Suture materials are fabricated by extrusion and may be made of resorbable or nonresorbable polymer. In your own words, when are resorbable sutures necessary and what specific polymer(s) should be used to make such a suture?

A

PLA and PGA are biodegradable. Nylon, polyester, PP, silk are not absorbable.

43
Q

What are the pros/cons of the three common polymers?

A

weaker than other biomaterials, cheaper, easy to process, more similar structure to tissue. PE and PMMA are hydrophobic (resist swelling).

44
Q

Describe in your own words, the functions of a biological hydrogel. Where in the body might these be found?

A

the patella and articular cartilage and the eye. They provide cussioning

45
Q

Distinguish between the three main types of cross-linking found within hydrogels.

A

physical, chemical, biological

46
Q

How may a hydrogel be designed to attract a certain cell type?

A

by putting drugs in the hydrogel

Biomaterials (1 decks)

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