Biomaterials

Front 1

Pi Bonds vs Sigma Bonds

Back 1

- Pi easier to break
- Pi easier to excite
- Pi much stiffer
- Pi help promote LRO

Front 2

Excitation Energy Equation

Back 2

E_exc ~ 1/lambda_exc

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Fluorescence

Back 3

Provide energy in form of light to excite valence electron

Front 4

UV-vis spectroscopy used for?

Back 4

Monitor peak intensity of absorption events for solution of molecules & macromolecules

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Relative Absorbance

Back 5

1 - I_x/I_o

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Absorbance equation

Back 6

A = (le)*c
l = path length (dim. of cuvette)
e = molar absorption coefficient @ lambda_char absorption
c = concentration

Front 7

Coordination Number (CN)

Back 7

Number ratio of one reference atom to all its nearest neighboring atom

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Lattice Point

Back 8

Individual point (or atom) within a crystalline lattice. Each lattice point is surrounded by identical arrangement of neighboring points.

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Basis

Back 9

Refers to a group of atoms associated with an individual lattice point.

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Unit cell

Back 10

smallest group of lattice points that completely describe the structural arrangement of atoms in a crystal or crystalline lattice.

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Close-packed planes & directions

Back 11

Easiest to move during plastic deformation

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Atomic Packing Factor

Back 12

Volume of atoms in unit cell / Total volume of unit cell

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Ceramic unit cells

Back 13

Ionic Solids

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NaCl Unit Cell

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Interpenetrating FCC unit cells

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CsCl Unit Cell

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Interpenetrating SC Cells

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Defect

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Disruption in the periodicity of a crystal

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Point Defect

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Disruption of a single lattice point or interstitial position

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Vacancy

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Missing an atom in a normally occupied position

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Interstitial

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Smaller atom that occupies an available space between lattice points

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Substitutional Atom

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Impurity atom that replaces an atom normally positioned at a lattice point

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Frenkel Defect

Back 21

Atom moves from one space within the lattice to another

Front 22

Schottky Defect

Back 22

Two atoms of opposite charge are removed from the lattice entirely

Front 23

Hume-Rothery Rules

Back 23

(1) Similar Size (<= 15% difference)
(2) Similar/identical crystal structure
(3) Similar electronegativity values
(4) Similar valency

Front 24

Diffusion Equation

Back 24

D = D_o * exp(-Q/(R*T))
D = Diffusivity (cm^2/s)
D_o = material constant (cm^2/s)
Q = Activation barrier (J)
R = gas constant (J/mol*K)
T = temperature (K)

Front 25

Diffusion requires:

Back 25

1) Free space
2) Activation energy (thermal energy)

Front 26

Flux

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Net # of atoms moving across the interface / unit time

Front 27

Fick's 1st Law:

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J = -(dC/dx) * D

Front 28

Polymerization Routes:

Back 28

1) Form new covalent bonds b/w different functional groups on monomers
2) Break pi bonds in UNSATURATED monomers to form new covalent bonds in polymer

Front 29

polyEthylene uses & Structure

Back 29

-joint implants
-flexible tubing (IV)

-(-CH2CH2-)n-

Front 30

Oligomer

Back 30

2-10 monomers

Front 31

Conformation

Back 31

Overall shape & structural attributes of polymer chain that can be changed through bond rotation

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Configuration

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Structural attributes of a polymer that can be altered by breaking covalent bonds

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"neat" or "melt" polymer

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100 wt% -- no solvent

Front 34

Stereoisomers

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Placement of side groups
1) Isotactic - identical arrangement of R
2) Syndiotactic - alternating R placement
3) Atactic - random R placement

Front 35

Steric Effects

Back 35

Size, chemical composition

Front 36

Edge dislocation

Back 36

Extra half-plane ends, causing a virtual line

Front 37

Burger's vector

Back 37

The extra vector required to close a box around a defect.

Front 38

Screw Dislocation

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Burger's vector parallel to dislocation line.

Front 39

Plastic deformation occurs through 2 routes:

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1) Creation of new dislocations
2) Movement of existing dislocations

Front 40

Dislocation glide

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movement of a dislocation line from the center of a material to the surface or edge

Front 41

Surface Tension

Back 41

planar defect on surface caused by unbonded atoms

Front 42

Grain boundary

Back 42

interface between crystals

Front 43

Void

Back 43

3D aggregates of vacancies

Front 44

Precipitate

Back 44

Cluster of substitutional or interstitial impurities

Front 45

Porogen

Back 45

chemical which promotes creation of voids

Front 46

platelets

Back 46

non-nucleated fragments of megakaryocytes

Front 47

platelet functions

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1. initially arrest bleeding by adhering to exposed collagen
2. conformational changes to integrin receptors on platelets:
a) further strengthens platelet adhesion to collagen
b) promotes platelet-platelet aggregation

Front 48

mediators of platelet adhesion to collagen:

Back 48

-GPVI (receptor on platelet)
-Von willebrand factor (ligand on collagen)

Front 49

Hemostasis Steps (5):

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1. Injury occurs - damages blood vessel & surrounding tissue
2. Platelets migrate to wound area & become activated by binding to exposed collagen
3. Activated platelets release granular content containing chemoattractants that recuruit & activate other platelets & recruit key molecules (e.g. fibrinogen monomers)
4. Fibrin Network forms
5. Platelet Plug fills the wound & serves as scaffold for repair.

Front 50

Fibrin Network Formation:

Back 50

Fibrinogen (unactive monomer precursor) --thrombin (secreted by activated platelets)--> fibrin monomer (active) --(Factor XIIIa + Ca++ allows formation of covalent bonds to form cross-linked fibrin polymer network)-->fibrin polymer network --(plasmin causes fibrinolysis)--> fibrin degredation products

Front 51

Hallmarks of Adaptive/Acquired Immune Response

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1. Specific
2. Diverse (genetic rearrangement)
3. Self & Non-Self
4. Memory

Front 52

Antibody (draw)

Back 52

1. Hinge Region
2. Binding pockets
3. disulfide bonds
4. Fab = antigen-binding region
5. Fc = crystallizable region (serves as ligand to bind to particular cell receptors)
6. IgM --> pentamer structure
7. IgA --> dimer structure

Front 53

Antibody Memory

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Naive T or B cell --> effector T or B or plasma cells --> clonal population --> regulation of effector cells --> leaves behind memory lymphocytes in case identical foreign invaders return to host

Front 54

Humoral Immune Response

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- Can be conferred to "non-immune" individuals
- B cells have Ig or Ab:
1. Immobilized on cell membrane
2. Secreted

Front 55

Role of Humoral Immune Response

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1. Ab binds to Ag to prevent Ag from binding to & invading host cells
2. Ab binds to Ag to mark it for phagocytosis by macrophages
3. Ab binds to Ag & then activates the complement system

Front 56

Complement System

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involves a complex mixture of different proteins that self-assemble on surface of foreign invader to membrane attack complex that results in a punctured hole

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Naive

Back 57

unactivated & has not yet been exposed to foreign Ag

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Epitope

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Binding domain of Ab which recognizes the Ag

Front 59

Types of T cells

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1. Helper T Cells
2. Cytotoxic T Cells

Front 60

Types of Helper T Cells

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TH1 - helps mediate plasma cell response
TH2 - helps mediate the Tc response

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Role of Cytotoxic T Cells

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recognize & kill non-self cells (e.g. infected host cells)

Front 62

3 types of primary bonds

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1. Metallic (delocalized electrons)
2. Covalent (sharing of electrons)
3. Ionic (electron donation)

Front 63

Electron subshells

Back 63

s - 2
p - 6
d - 10
f - 14

Front 64

UV-vis spectroscopy vs Fluorescence

Back 64

Antibonding & Bonding instead of Excited & ground state.

Front 65

PVC uses

Back 65

-less flexible tubing
-plasticizers often added to lubricate chain sliding

Front 66

Polyethylene oxide OR polyethylene glycol structure

Back 66

-(-CH2CH2O-)n-

Front 67

Polymethylmethacrylate (PMMA) structure

Back 67

-(-CH2CCH3COOCH3-)n-

Front 68

General structures of polymer chains (3)

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1. Linear
2. Branched
3. Network

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Network polymer junction sites

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formed either through bonding (more likely) or physical entanglement

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Crosslinking

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involves formation of new covalent bonds at junction sites aka crosslinking sites

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Hydrogel

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network polymer which is hydrophilic (as many network polymers are).

Front 72

BIS

Back 72

common crosslinker.

Front 73

Polyvinyl alcohol (PVA) structure

Back 73

-(-CH2CHOH-)n-

Front 74

Copolymer

Back 74

1. random (ABBABAAA...)
2. Alternating (ABABAB...)
3. Block (AAAABBBB...) (most common)

Example: PLGA = poly(lactic-co-glycolic acid)
- often used in drug delivery applications due to its biodegradability

Front 75

Step polymerization

Back 75

-polymer chains grow stepwise between any 2 reactive species
-monomers have 2 or more reactive sites
-monomer is used up quickly
-often has byproducts
-continues until no reactive sites are left

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Chain polymerization

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-monomers are typically unsaturated
-chain grows only by rxn of monomer with growing chain
-"break" unsaturated bonds to form new covalent bonds
-no byproduct
-involves distinct stages

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stages of chain polymerization

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1. Initiation
2. Propagation
3. Termination

Front 78

chain polymerization initiation

Back 78

Create free radical center from initiator species which often contains peroxide or azo bond (draw schematic)

Front 79

chain poymerization propagation

Back 79

bond monomer to free radical monomer end (draw schematic)

Front 80

chain polymerization termination

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a) combination - usually results in head-head orientation
b) disproportionation - involves movement of hydrogen from one monomer end to another

draw schematics of each

Front 81

Number average molecular weight

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Mn = sum(Ni*Mi)/sum(Ni)

Front 82

Weight average molecular weight

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Mw = sum(Ni*Mi^2)/sum(Ni*Mi)

Front 83

Diffusion Time/distance equation

Back 83

x=sqrt(D*t)

Front 84

Polyacrylamide

Back 84

(-CH2CHCONH2-)

Front 85

PVC

Back 85

CH2CHCl

Front 86

Monomer "head" and "tail"

Back 86

Head = C connected to side group
Tail = other C

Front 87

Chain Scission via oxidation (propagation and termination)

Back 87

See picture

Front 88

Homolysis (draw)

Back 88

2 r groups with one free radical each

Front 89

Heterolysis Initiation (draw)

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2 r groups, one positive, one negative

Front 90

Spherulites

Back 90

3D aggregate of lamellae (crystalline domain) and amorphous regions that radiate from center

Front 91

Lamellae

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crystalline domain of a polymer

Front 92

Shear stress equation (liquid)

Back 92

t = ns*
n = viscosity
s* = strain rate = ds/dt

Front 93

shear stress equation (elastic solid)

Back 93

t = Gs
G = elastic modulus
s = strain

Front 94

viscoelastic complex modulus

Back 94

= G + iG"
G = shear elastic modulus
G" = shear loss/viscous modulus

Front 95

Exchange of one adsorbate for another with higher affinity.

Back 95

Vroman effect

Front 96

method used to separate and identify DNA sequences

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Southern blotting

Front 97

EM proteins undergo enzymatic breakdown & rearrangement, aka

Back 97

remodeling

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Cells that are completely able to replicate or proliferate

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labile cells

Front 99

cells that can be cued to replicate, but not as readily.

Back 99

stable cells

Front 100

cells that are least liekly to replicate

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permanent cells

Front 101

stem cells that are capable of differentiating into any cell phenotype

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totipotent

Front 102

stem cells that are capable of differentiating into various blood cell phenotypes

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hematopoietic

Front 103

Explain the DVLO theory (forces involved, graph)

Back 103

refer to book

Front 104

Name transport mechanisms for proteins to arrive at a biomaterials surface

Back 104

diffusion, flow, convection

Front 105

Name two methods for separating proteins, which results in faster migration of proteins?

Back 105

SDS-PAGE & SEC

Faster: SEC

Front 106

Soluble chemical factors secreted by cells to affect the behavior of other cells

Back 106

cytokines

Front 107

Organelle responsible for post-translational modification

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golgi apparatus

Front 108

EM protein which undergoes post-translational modification outside the golgi apparatus

Back 108

collagen

Front 109

Define biomaterial

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any nonviable material intended to interface with biological systems to evaluate, treat, augment, or replace any tisue, organ or function of the body.

Front 110

Different types of RNA

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- mRNA (messenger)
- tRNA (transfer)
- rRNA (ribosomal)

Front 111

Different types of cytotoxicity assays

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1) direct contact
2) agar diffusion
3) elution

Front 112

4 steps in neutrophil recruitment to injury site

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1. Rolling (bind briefly to endothelium via selectin-carbohydrate)
2. Activation (chemoattractants IL-8 & MIP-1b)
3. Arrest (integrin binding to endothelium)
4. Migration through endothelium

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2 routes neutrophils use to destroy foreign material

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1) phagocytosis
2) secretion of reactive o2 & n2

Front 114

5 stages to normal wound repair following injury

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1) bleeding & clotting
2) inflammation
3) granulation tissue formation
4) foreign body reaction
5) fibrous capsule formation

Front 115

3 Important considerations when dealing with biomaterials

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- Processing
- Properties
- Structure/Composition

Front 116

How to denature proteins

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SDS or heat

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how to denature DNA

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heat

Front 118

purpose of ELISA

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to identify specific proteins based on their antibody binding

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purpose of Western Blotting

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to separate proteins based on their molecular weight alone

Front 120

3 types of cytoskeleton

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- microfibrils
- intermediate filaments
- microtubules

Front 121

define physicochemical (in reference to coatings)

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any method of surface coating that is not biological

Front 122

Self-Assembled Monolayers (SAMs)

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amphiphilic molecules which contain an attachment group

Front 123

Langmuir-Blodgett film

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refer to book pg 239