midterm 1 Flashcards
What are the 3 classes of materials? (and describe them)
- Metals - metallic bonds, sea of electrons
- Ceramics - ionic bonds, nondirectional
- Polymer - covalent bonds, directional
What is an example of a metal?
Titanium, gold, etc.
What is an example of a ceramic?
NaCl2, Hydroxyapatite
What is an example of a polymer?
PEG
What is an example use of metal biomaterials?
Dental Implants
What is an example use of ceramic biomaterials?
Bone scaffold, hip implants
What is an example use of polymer biomaterials?
Drug delivery, skin grafts
What are the types of material degradation, and explain what their difference is?
- Surface - layer by layer removing
- Bulk - equal degradation throughout the material
What are some traits that can be controlled by changing a material’s surface properties?
- cell adhesion/spread, by modifying the surface texture
- protein interactions
What can you do to modify the surface texture?
- or - charge
- increase the surface energy
- change hydrophobicity
What are two mechanical properties? Also, are they surface or bulk?
- softness/hardness - surface
- compliance - bulk
What is the equation for stress? (and units)
σ=F/A (units N/L^2)
What is the equation for strain? (and units)
ε=ΔL / l₀ (units L/L)
What are chemical characteristics?
- composition of biomaterial
- chemical structure
- conformation of reaction
What are some imaging techniques that can determine chemical characteristics?
- NMR (nuclear magnetic resonance)
- raman spectroscopy
- FTIR
What components make up a polymer?
monomers
Describe the structure of a copolymer
different repeated monomers
What are the steps of addition polymerization? (and products)
- Initiation - radical combine with double bond to make two single bonds
- propagation - multiple units chain together
- termination - stop adding more units
What is condensation polymeration? (and products)
Combining multiple chemicals to form a product polymer and water
Draw the structure of polyester
-R-O-R-CO- (see pdf)
Draw the structure of polyether
-O-R- (see pdf)
Draw the structure of polyanhydride
-CO-R-CO-O- (see pdf)
Draw the structure of polyamide
-CO-R-NH- (see pdf)
Draw the structure of polyurethane
-O-CO-NH-R- (see pdf)
What is the equation for PDI?
PDI = Mw / Mn
What is the equation for Mn?
Mn = Σ Xi Mi
What is the equation for Mw?
Mw = Σ Wi Mi
Rank the 4 types of polymer structures from strongest > weakest
Network > Crosslinked > Linear > Branched
strongest > weakest
Draw chain-fold structure
/\/\/\/\/\/\/\/\/\/
wewewewewewewew
What is the thermoset process?
to set a polymer using heat
What is a thermoplastic?
A plastic that can be reheated to change shape
What are examples of elastomers?
- Elastic
- Rubbers
What are 4 structures of copolymers?
- Random
- alternating
- bulk
- graft
What are types of natural polymers?
- Polypeptides - protein - amino acids is hetero bifunctional condensation (zein, gelatin, elastin)
- polysaccharides - sugar (hyaluronic acid)
What is a common example of a natural polymer?
DNA (long length, bound with hydrogen bonds)
What are the structures of proteins
- 1 (primary): Alu-gly-arg-
- 2 (secondary): organization of local amino acids into alpha-helices, beta-sheets, and loops
- 3 (tertiary): combine secondary structures
- 4 (quaternary): 1+protein
What are common side chains for alpha helices? (and examples)
- bulk side chains - uncommon
- lack side chain - uncommon
(glycine, protein)
What are common chemical pairs in beta sheets?
- C-N in parallel
- C-N
- C-N antiparallel (more stable)
- N-C (small hydrogen bond angle)
What are advantages and disadvantages of natural polymers
- Advantages: bioinert, bioactivity, hydrated
- Disadvantages: highly variable, hard to purify, immune response
What are advantages and disadvantages of synthetic polymers?
- Advantages: cheap, reproductive, not animal derived (low immunigenicity)
- Disadvantaes: unknown toxicity, no inherent cell interaction
What is the equation for degredation? (and what numbers indicate surface vs. bulk?)
rate of hydrolysis / rate of H20 entry
|»_space;1 surface, «1 bulk
What are 3 methods of degredation for polymers? (describe)
- Biodegredation - mediated by biological agent
- Bioerosion - physical dissolution
- Bioresorption - polymers removed by cellular activity
What is PEGylation
A process of conjugating one or more PEG polymer to a molecule to modify its size, hydrophobicity, and stability.
What are benefits of PEG?
- Making a larger - reduce renal clearance
- Stability - harder to degrade
- Hydrophobicity - last longer
- Increase circulation half-life
What is bioconjugation? (give details)
A + B –> A-B (conjugation)
The inative group A reacts with the initiating group EDC to form an active intermediate. This reacts with coupling target B to form the stable conjugate product A-B.
What is the most useful functional group in cysteine?
SH
What is the most useful functional group in serine and threonine
OH
What is the most useful functional group in tyrosine?
PhOH
What is the most useful functional group in lysine?
NH2
What is the most useful functional group in aspartic and glutamic?
CO2H
