Exam 3

Question 1

L22. Describe what is meant by the term “wound Care Market”

Answer 1

Def: products for wound closure and those offering protection against drying out and infection-basically products that let the wound heal on its own

advanced: films, foams, ECM, tissue engineered and combination products developed to accelerate or promote faster and more efficient wound healing using knowledge of the ongoing biology.

Question 2

List the goals of an ideal wound care product

Answer 2

1. Hemostasis-closure/basic wound care
2. Environmental Protection
3. Minimize Scarring

REAL
Enhances healing process
-maintain a moist wound environment
-permit gas exchange
-mechanically support tissue until strength is increased
-Accelerate or actively promote healing
-Minimize Scarring

Reduce risks that inhibit wound healing

• protect against addt’l trauma/temp. changes
• absorb exudate
• non-adherent to healing tissue to allow removal.

Lower incidence of infection
-provide barrier to pathogens

Question 3

Describe three different methods to close a wound

Answer 3

Bandages

Sutures
-thread-like biomaterials used to sew tissue together or to ligate blood vessels;
-Classified accourding to
–fiber construction
–composition
–absorption characteristcs
-usually thermalplastic material, some natural
-different sizes microns-tow a car
Construction:
-monofilament-easy to glide through tissue, more difficult to tie, must be handled carefully
-braided monofilament
-braided fine: many monofilaments woven together
made by melt spinning process
Props: strength/elasticity should be comparable to target tissue

Staples
for closure of long incisions/surgical lacerations
-scalp/abdomen made from stainless stell
-quick, secure, reduced infection risk
-leaves more visible scar, must be removed, more painful

Adhesives
indicated for the closure of surface incision (laproscopic) or traumatic alcerations
cyanoacrylate monomers ~ superglue
-quick, painless, need not be removed
-limited strength, not approved for internal usage

Wound Dressings

Question 4

How would you differentiate the FBR around a non-absorbate suture and a typical wound healing process that does not involve a foreign body introduced in the wound?

Answer 4

FBR to non-absorbable sutrue is the same as to an implantable biomaterial device, which includes chronic inflammation and fibrous encapsulation

FBR is more active initially w/ degradable device, because surface area of sutrue increases while it’s breaking down,but eventually, it goes away. Leaves behind a larger scar due to replacement of FBR cells by connectie tissue

Question 5

What is the major difference in using a traditional gauze dressing as opposed to an active wound care product?

Answer 5

traditional doesn’t interact with biology, allows body to do its thing. used for draining necrotic wounds.
Ad: protection from dirt, gas permeable, inexpensive
cons: limited infection protection, does not maintin moist… can adhere to wound.

active, tries to interact with, augment or alter the rate of body’s natural processes-composed of hydrophilic elastomers. can elate drugs

Film dressing (polyurethane)- used for caheter fixation and anti-infective transparent dressing

pros: flexible, transparent, gas permable water proof
cons: non-absorptive so must be changed when exudate is present-no protection against…..

foam dressings: for minimal to heavy draining wounds, late stage ulcers, partial or full-thickness wounds
advantages; good for heavy draining, protective, high absorbency, gas permeable, can be packed deep into wounds
cons: if not changed frequently can accumulate….

hydrocolloids: mostly composed of Na-caboxymethylcellulose or gelatin-light to moderate draining superficial wounds-applied as dry sheet which absorbs exudate
cons: can led to coming off wound bed

hydrogels: ex. alginates-for full thickness wounds w/ moderate drainage-applied dry.
cons: difficult to keep in place, can promote bacterial proliferation

biologics: made from natural biomaterials that play in active role inthe wound healing process. ex. collagen/hyaluronic acid
pros: biodegradable, bioactive, stimulates wound healing. removes inflammatory molecules

bioengineered skin substitutes: living cells+polymer scaffolds

pros: can replace damaged tissues, cells secrete growth factors which can be stimulate wound healing, can be used for chronic wounds
cons: very expensive

Question 6

As part of your new career you are asked to invest millions of your firms savings in the wound care product market. What product or products would you invest in and why?

!!!

Answer 6

active wound care products!!!
bioengineered skin and skin substitutes(14% growth)
alginate dressings (16% growth)
hydrogels(less than 500 million, 12%)
foam dressings (most millions,12% growth)

most growth, diverse by aggressive

Question 7

List 4 major application areas for biomaterials in Cardiology

Answer 7

Vascular Access

Vasculature Repair Devices

Cardiac or Cardiac related devices

Extracorporal Device (artificical heart, blood/gas)

Question 8

In your opinion, what is the most important material used in cardiology applications and why?

Answer 8

?? Open Ended, will be on the exam
-like class of polymers-- be able to rationalize,

Question 9

What is a stent and how are they used?

Answer 9

Stent: tubular metallic mesh used to provide structural support to vessel walls and flatten plaques after angioplasty
made of: 314 Stainless steel, Co-Cr, Nitinol, Bioresorable polymers

placed in artery. balloon deploys and stent placed in vessel to mechanically hold the plaque.

Question 10

What is the major problem impacting the efficacy of stenting and describe two ways companies/researchers are trying to address the problem.

Answer 10

Restenosis in ~25% within 6 months. Causes primarily fibrous scar tissue, does not produce an optimal glycocalyx because endothelial cells do not completely line the lumen.

Drug Eluting Stents:
2003 Sirolimus (Cypeher):
antifungal rapamycin derived from easter island bacteria, immunosuppresant, antiproliferative, moderate incidence of renal failure.

Bioresorbable Stents

Question 11

What is a vascular graft and how are they used?

Answer 11

Vascular Graft: a substitute vessel which is used when a natural blood vessel fails;

used when autologous vessels: saphenous vein/mammary artery–use real cells to replace.

2nd options are synthetic vessels.

• treated allogenic or xenogenic tissue
• synthetic polymer fabrics
• laboratory-engineered tissue

Question 12

Why is there a need for artificial vascular grafts?

Answer 12

There is a limited supply of your own vessels to use.

Question 13

What are the three major types of vascular grafts?

Answer 13

1. veins from your own body
2. Synthetic polymer
   3 Laboratory engineered tissue (allogenic)

Question 14

What are the ideal properties of a vascular prosthesis?

Answer 14

Achieve and maintain hemeostasis
low thrombogenicity
low incidence of embolic shedding
promotes endothelial cell adhesion/proliferation
good suture retention

• achieve and maintain hemostasis
• low thrombogenicity
• low incidence of embolic shedding
• promotes endothelial cell adhesion/proliferation
• good suture retention
• adequate burst strength
• high fatigue resistance
• ability to be manipulated in a surgical setting

Question 15

What are the common complications with any type of vascular graft?

Answer 15

Perform poorly in low-flow, high resistance locations.

Thrombosis and Thromboembolism 
Infection 
Pseudoaneurysm 
Intimal hyperplasia (overactive physiologic repair response) 
Structural degradation

Question 16

What are the most common complications of heart valves?

Answer 16

synthetic/tissue

stenosis and regurgitation.

Thrombosis and thromboembolisms. Infection. Calcification. Structural failure.

Calcification
Infection
Thrombosis 
Thromboembolism 
Structural failure (regurgitation)

Question 17

What are the major advantages and disadvantages of mechanical and tissue valves

Answer 17

A. Mechanical - Advantages: durability, less frequent replacement. Disadvantages: patient must be on anticoagulants, noticeable clicking noise.
A. Biological - Advantages: patient does not need to be on anticoagulants, no noticeable noise. Disadvantages: increased rate of valve failure, more frequent replacement procedures.

Mechanical Advantages - Durability (15-20 years), Less frequent replacement
Disadvantages - Patient must be on anticoagulants, Noticeable ‘clicking’ noise
Biological Advantages - Patient does not need big supplies of blood anticoagulants*, No noticeable noise
Disadvantages - Increased rate of valve failure, More frequently replacement procedures (lasting around 10 years)

Question 18

What is meant by the term “cardiac pacemaker” and what are their basic component parts

Answer 18

A cardiac pacemaker is an implanted device that electrically shocks the myocardium to help control or restart heart rhythms. The basic components include the pulse generator, and the two pacing leads.

Cardiac pacemakers are medical devices that provide impulses to the conduction system to initiate contraction.
A pulse generator which includes a power source and circuitry to initiate the electric stimulus and to sense cardiac electrical activity.
One or more electrically insulated conductors leading from the pulse generator to the heart, with a bipolar electrode at the distal end of each.
A tissue or blood and tissue interface between electrode and adjacent simulatable myocardial cells.

Question 19

Provide a definition of the term hydrogel and provide two biomedical applications of this class of polymers

Answer 19

Water insoluble, three dimensional network of natural or synthetic hydrophilic polymeric chains that are connected by weak forces or covalent linkages capable of swelling (usually by at least 10-20%) in aqueous conditions.

Applications:
wound healing products
drug delivery
ophthalmic applications
reconstructive and cosmetic applications

Question 20

Using structural models provide two different schemes for fabricating a hydrogel network

Answer 20

Models mean drawings/diagrams.

hydrophobic polymer -> polar groups

from polar groups you either get chemical hydrogel or physical hydrogel

Be able to discuss chemical reactions that can form network compared to something that has physical reactions to form a network. Label drawing to prove understanding.

Question 21

How are hydrogel properties used in drug delivery? Proide at least one example

Answer 21

Swelling mediated Release
-As polymer swells and pore size increases, the drug can diffuse out.

Osmotic Pumps

• xerogels can be used to deliver drugs via osmotic pumps
• semipermeable membrane on exterior, thin elasteric membrane, inbetween the 2, there is xerogel, squeezes, and fluid is pumped out.

Question 22

What is meant by the term “natural hydrogel” and provide 2 examples

Answer 22

components of soft tissues. Biological samples that act as hydrogels that are not synthetic and are recognized by the body as natural.

poly(hyaluronic acid): non-sulfated GAG, found in connective, epithelial, and neural tissues

poly(sodium aglinate): polysaccharaide found in cells walls of brown algae

Def:
Derived by natural or biological molecules, natural tissues, or composed from an organism Examples:
Decellularized tissue
Polysaccharides

Functions:
decrease permeability to large molecules
add compressive strength
improve clearance of molecules
improve sliding/gliding
acts as a non-fouling and anti-thrombic surface

Question 23

What is meant by the term “Biometric Engineering”? Provide an example of such an approach

Answer 23

When you take something from nature and engineer it to be useful for your purpose.

immunoprotection for cell transportation

TRESCO: An engineering approach where lessons learned in nature are used to solve a practical problem or used in the design of a biomedical device. An example would be the use of sodium alginate to encapsulate living cells as an immunoprotective covering as happens in biofilms.

Question 24

How would you use the cell encapsulation approach to treat Parkinson’s disease?

– question won’t be asked, can disregard

Answer 24

implant dopamine secreting cells into the dopamine deficient brain tissue of a Parkinson patient

–question won’t be asked

Question 25

What device attributes are required in a clinically effective contact lens product?

Answer 25

``` Gas Permeable-oxygen soft flexible hydrophilic good mechanical stability favorable refractive index ```

Question 26

What are the most common contact lens materials to date and how are contact lenses made

Answer 26

combination contact lenses Galyfilcon A SenofilconA ``` TRESCO: Glass (less than the other 2), PMMA, Silicone -computer assisted lathing/polishing -spin casting-polymerization -molding-polymerization ```

Question 27

What are the major bicoompatibility issues related to contact lenses and how are the issues connected to the materials?

Answer 27

``` high coefficient of friction low oxygen transmissibility low wettability modulus lens dehydration lens replacement frequency thickness and edge configuration ``` Biocompatibility issues with contact lenses can lead to contact lens discomfort due to the high coefficient of friction, low oxygen transmissibility, low wettability, certain surface modifications, modulus, lens dehydration, lens replacement frequency, and thickness and edge configuration. An additional issue is corneal damage, which is physical abrasion or no longer getting oxygen to eyes.

Question 28

What is an "IOL" What are the problems encountered with these devices? How are these issues connected to the FBR to the implant?

Answer 28

Intraocular Lenses Have haptics, extend into ligament, and hold lens in place. temporary implant. often need to be revised every 2-5 years. ``` Revisions needed due to: incorrect lens power glare optical aberrations dislocation/decentration late postoperative opacification ``` Macrophages and fibroblasts grow on lens. FBR on lens is what causes opacification. phospholipid serves as site where hydroxyappetite grows. Rigid: PMMA Foldable: Siloxanes/Acrylates

Question 29

Develop an innovative strategy for preventing ocular shunt occlusion to improve glaucoma treatment WILL BE ON FINAL

Answer 29

Problems w/ shunts: failure due to fibrotic occlusion of shunt 1/3 of patients develop Choroid detachment occular motility often decreases and may become painful

Question 30

What is a metal and how does its bonding structure underlie its properties (explain at least one structure function relationship)?

Answer 30

Def: a dense, crystalline material that consist of one or more elements that readily share their electrons. nucli are cations, share electrons. sharing of electrons provides them with their properties. sea underlies most properties we take advantage of Shiny: photons are absorbed by free electrons. which jump to higher energy level, when they fall back down, they emit light conductors: when metal is heated, free electrons vibrate, increasing KE and temp. when current is applied, electrons enter in one side and generate movement. same number exit that entered malleable: when metal is hit, it deforms because sea of electrons shield cations from each other, preventing repulsion ductile: cations line up and are shielded from one another by sea of electrons

Question 31

How are stock metals made? | unlikely to be asked, still should know

Answer 31

Need to break down crystalline latice Raw: casting (forms ingots): --casting is the shaping of a metal by pouring it in the liquid state into a mold followed by solidification --liquid to solid phase change is accompanied by a change in volume and microstructure. Crystals solidify in process called Nucleation, initial crystals grow will grow along an axis until there is interference. called grain boundary. size, orientation and size distribution of grains affect the performance of metal and physical properties forging, rolling Powder: TRESCO: Generally by casting where the stock metal shape is made by pouring the metal in the liquid state into a mold follwed by solification

Question 32

What could you do as an engineer to affect the grain boundary distribution in a metal to improve its fatigue resistance?

Answer 32

Forging Recristallisation Forging: heat and pound/deform it while cooling Under tension Cool more slowly, to allow smaller grain formation Push through roller/compressor during forging, to force the alignment of grains. Alloying with vanadium Cool it slower so the crystalline structure forms more evenly (more homogenous) - less issues in the grain of the metal so it wont shatter or break as easily. Alloy - tougher than pure metals. Forging under tension/compression. HIP (Hot Isostatic Pressing) Definition: a manufacturing process in which metal powders are turned into compact solids by exposing the component to elevated temperature under isotactic gas pressure (typically Argon or Nitrogen) in a high pressure containment vessel. It is used to reduce the porosity of metals and increase the density of ceramics. It improves the materials mechanical properties and fatigue resistance.

Question 33

Why are alloys generally tougher than pure metals?

Answer 33

Alloying is a mixture of metals made by combining 2 or more elements in orde to generate alloys interstitial - -smaller elements fill holes that are in the main crystal structure - -increases mechanical strength substitution --condition in which atoms of different elements of similar size substitute within the crystal structure

Question 34

Describe how you would make a metallic stent for use in repairing the esophagus. In your description describe what material you would use and how you would go about fabricating the stent structure?

Answer 34

Use Nitinol !! see youtube video Nitinol wire is winding (knitted) around a jig, then it is heated to imprint the memory, lock in the structure. The stent is then polished by abrasive particles, which reduces microcracks, and removes impurities from the surface. follow up youtube video-- notice the stages!!! knit, heat to lock in structure, polished.

Question 35

Define a bioceramic and give two examples of these biomaterials

Answer 35

Def: solid, crystalline, inorganic compounds formed from combinations of a metal (Al, Zr, Ti) and a more electronegative elements through combinations of ionic and covalent bonds Examples: Bioinert: unreactive w/ living tissue -Aluminum oxide (Al2O3) or Alumina -Zirconium dioxide (ZrO2) or Zirconia Bioactive: induces a specific cellular reaction - Calcium phosphates - Bioactive glass (SiO2, CaO, Na2O, P2O5)

Question 36

Why do ceramics have very different physical properties than metals?

Answer 36

Presence of covalent bonding means that electrons are held much tighter than metals, leads to low conductivity, low ductility (very brittle), high stiffness and high melting point. Presence of electronegative element affects grain structure, they become a lot more uniform and smaller. That's why they're much harder than metals, but also makes them brittle. Addition of covalent bond leads to higher melting and processing temperatures. Also leads to restricted electron movement and thus is not as good of a conductor. Cracks propagate because of small grain sizes.

Question 37

Name two generally accepted design advantages of using ceramics in a biomedical device and provide an example to go along with each one?

Answer 37

TRESCO: 1. wear resistant 2. Compressive Strength 3. Asthetics (nice to look at)

Question 38

Describe how you would fabricate a femoral stem made entirely of alumina

Answer 38

Once ore is mined, it goes through the Bayer process to be ground in to a fine powder. Powder is Sintered in a mold, temperature is brought to near melting and under pressure, the grains are fused together. Then the piece is ground and polished.

Question 39

What is meant by the term "calcium phosphate" and what is a rationale for its use?

Answer 39

is a bioactive ceramic. natural ceramics (biocermaics) constitute the principle inorganic phase in norm calcification (?) in teeth and bone, this mineral is hydroxy appatite, put together in a hexagonal crystal bioactive (osteoinductive) activates osteoblasts to osteocyte. Ca5(PO4)3 (???) used as coatings to enhane osteo integration. applied as a powder in a plasma jet process

Question 40

Given what you know about orthopedic devices, which market segment would you invest in and why?

Answer 40

market projected to be at $66.2 billion/year WOULD INVEST IN: Joint reconstruction, spinal devices WHY: highest revenue. largest growth rate. knee's dominate with hips 2nd, followed by spinal devices, which is growing. mostly trauma management.

Question 41

Given what you know about the FBR to inert implant matreials provide a hypothesis to explain the biologic mechanism of what is referred to as aseptic loosening. likey

Answer 41

aseptic loosening and periprosthetic fracture (chronic phase) (is this just constant macrophage activation??) TRESCO: persistant macrophage activation results in bone resorption. Osteoclasts resorb bone. Because macrophgaes are constantly activated, will lose bone density

Question 42

What is the difference between arthroscopy to arthroplasty? likely

Answer 42

Arthroscopy: a surgical approach where a tube-like instrument is inserted into a joint to inspect, diagnose, treat or repair tissues. Arthroplasty: A surgical procedure where the articular surface of a joint is replaced, remodeled or realigned to either relieve pain or restore function after damage by arthritis or trauma

Question 43

What is meant by the term "osseointegration" and how would you treat a biologically inert metal to make it more osteoinductive?

Answer 43

The process where bone grows into or onto an implant. Using a combo of surface roughness and bioactive ceramics can promote bone formation and better integration. -surface roughness that resembles natural Ca-Phosphate grains hydroxyapatite ECM coatings Chemical Functionalization and Growth Factors.

Question 44

What recommendation or innovation would you make to improve the biocompatibility of standard internal fixation devices

Answer 44

follow up, end of L28 internal fixation are nails/rods, pins, wires, screws, plates -all stainless steel, similar to what you could buy at Home Depot TRESCO: Surface coatings, like hydroxyappatite. or surface roughening make it out of titanium that promotes osseointegration

Question 45

What is meant by the term "dental restoration" and what are the two most common approaches used?

Answer 45

Process to restore the function, integrity or form of a damaged tooth due to cavities or trauma. 1. inserting a material directly into the damaged region of the tooth (fillings) 2. biomaterials that cover the damaged or decayed tooth.

Question 46

Why is the mouth a particularly challenging tissue for implant surgery? likely

Answer 46

Microbiome, enamel doesn't regenerate. The Oral Microbiome - over 700 species of bacteria colonize the hard surfaces of the teeth and oral mucosa, the teeth are the only non-shedding surfaces in the human body, the ecological plaque hypothesis. Tresco: oral microbiology, variability of oral hygiene, and/or the immune status of the patient. TRESCO Micriobiome, particular flora that respond by producing acid. remember, animals don't get cavaties. so many bacteria and they promote FBR- STREP MUTANS

Question 47

Describe two different approaches to improve the longevity and functionality of dental implants

Answer 47

threaded implants. Surface treatment to improve osseointegration around implant, establish a soft tissue carrier that protects underlying hard tissues and the implant host interface. Longevity and functionality of dental implants depend upon: • the level of osseointegration around the implant body • the establishment of a soft tissue barrier that protects the underlying hard tissues and the implant host interface Additionally, two treatment options for dental restoration include inserting a material directly into the damaged region of the tooth (fillings) and fabricated materials outside of the mouth (crowns). Surface treatment to improve osseointegration Increase surface roughness Calcium phosphate or Hydroxyapatite coatings

Question 48

List 4 material requirements for restorative materials and provide an example of two materials used

Answer 48

``` Chemically Resistant Hard Wear Resistant Low thermal conductivity aesthetic ``` Metal Alloys & Porcelains USED: precious metals, gold, gold platina alloy, silver-palladium alloy, follow up bioceramic materials: composite resin, glass ionomer cement, porcelain

Question 49

Describe three complications associated with dental implants placed in bone?

Answer 49

Inflammation of the dental pulp or adjacent gingiva, increased plaque accumulation on composite resin fillings, allergic reactions with extra- and intraoral symptoms, infection, infection related loosening, mechanical failure, gingivitis, bone absorption. Infection from implant Aseptic loosening Bone resorption secondary to inflammation taps into very dense bone

Question 50

L30. Differentiate between the terms adhesive and sealant.

Answer 50

Adhesive: a natural or synthetic substance used in the fabrication of a biomedical device to bond materials together or to bond living tissue together. Most are polymers and are applied during polymerization or the “cure” step, in which polymerization takes place simultaneously with adhesive bond formation. Sealant:a natural or synthetic substance used to close a gap between in a medical device or tissue surfaces and prevent things air or other bodily fluids from crossing the gap. Used to seal the outer surface of a medical device or to stop bleeding, sealing a surgical incision to stop leakage in the respiratory system, GI tract, stop cerebrospinal fluid leaks, reinforce tissue around sutures or staples.

Question 51

As a design engineer, what generally needs to be considered in the selection of a particular adhesive?

Answer 51

TRESCO: The wetting nature of the adhesive and the surfaces that are going to be joined, surface roughness, surface cleanliness and the mechanism of adhesive solidification. Duration perhaps

Question 52

Differentiate between different bonding mechanisms.

Answer 52

TRESCO: 1. VdW (not an answer) 2. Mechanical interlocking 3. protein adsorption 4. Covalent Bond formation

Question 53

From a biomedical engineering perspective, what are the benefits and limitations of adhesives?

Answer 53

TRESCO: Ease of application, set or cure time, mechanical properties, durability or fatigue resistance, color/transparency, limits: toxicity and cost

Question 54

What is meant by the term “bone cement” and how is it used?

Answer 54

Polymethylmethacrylate: used for fixation of artificial joints to the skeleton and acts more as a filler Polymethylmethacrylate - used for fixation of artificial joints to the skeleton and acts as a filler, one part liquid, light cured for faster cure rates.

Question 55

Describe how sealants are used.

Answer 55

A common one in biomedical applications is fibrin sealants. Used primarily as a hemostatic agent and tissue adhesive. Promote wound healing but can lead to scarring. Earliest surgical glues used to mimic the late reactions in the clotting cascade; Consists of components obtained from pooled human plasma –fibrinogen and thrombin and calcium; Reacts with surrounding tissue in minutes and acts as a hemostatic agent; Used to stop bleeding after surgery or prevent accumulation of post-operative fluid; Limitations include expense, low availability with possible disease transmission, poor to moderate adhesion strength in wet wounds and not suitable for elastic tissues like the heart and lung;

Question 56

L31. Define the term biodegradable and describe several advantages for their clinical use

Answer 56

A natural or synthetic macromolecules that is broken down over time into non-toxic components following prolonged contact with living tissue or a biological fluid. do elicit a FBR that is often greater than their solid counterparts all are synthesized by condensation reactions, hydrolyzed w/ aqueous environment advantages: - provide a temporary function - Do not require a second surgery for removal - Rate of breakdown and resulting change in mechanical properties can be engineered to meet the need of an application.

Question 57

What are the advantages of synthetic degradable polymers over natural ones?

Answer 57

Unlimited Quantities Control over chemical and physical structure -crystallinity, porosity, degradation rate, mechanical properties, shape free from concerns of immunogenicity. dis: potential for toxicity due to degradation by-products

Question 58

What do you suspect determines whether a material will degrade by surface versus bulk erosion and why?

Answer 58

Microstructure which is due to synthesis/processing Bulk: -low degree of crystalinity, material absorbs water all over. Surface: -high degre of crystallinity, water penetrates slowly into device and gets smaller and smaller and smaller over time. TRESCO: - hydrolytic susceptibility of the polymer backbone - hydrophoilic/hydrophobic nature of the repeat units - initial MW - degree of crystallinity of microstructure - Morphology and surface area of the structure

Question 59

List the most important factors that affect the behavior of degradable polymers?

Answer 59

Backbone Chemistry, Microstructure-degree of crysallinity Hydrophilicity=faster degradation Crystallinity=slower degradation Morphology=faster -MW=slower - TRESCO: -hydrolytic susceptibility of the polymer backbone -hydrophoilic/hydrophobic nature of the repeat units -initial MW -degree of crystallinity of microstructure -Morphology and surface area of the structure

Question 60

What specific area of medicine do your predict will be the largest growth area for the use of biodegradable polymers in the future and why?

Answer 60

degradable orthopedic devices: popular outside of US, just waiting to take off here Temporary barriers during wound healing drug delivery vehicles

Question 61

How would you improve the effectiveness of medical practice today? (3 ways)

Answer 61

Open ended, think about it and be able to rational! put medical people in charge of business, abolish private insurance- allow everyone to obtain care they need; reform health education

Question 62

What is the economic potential of regenerative medicine and what segment of the market would you invest in and why?

Answer 62

Market includes - Growth Factors - Cell Therapy - Biomaterials - Engineered Tissues Funding/Potential currently worth 13.4 Bil by 2021 expected to be worth 38.7 Bil. FOLLOW UP

Question 63

What are the factors that determine whether you might choose to use an extracellular matrix scaffold over synthetic biodegradable ones

Answer 63

``` Will not activate FBR Integrate and signal ... 3-dimensional Can be tissue specific to binding domains Architecture ``` ECM derived: complex natural architecture (won't activate FBR), inherently immunomodulatory, promote hemostasis, promote wound healing, degrade quickly, will integrate for migration and expansion, 3D, tissue specific. Factors: architecture, stability, resorption rate, bioactive, strength, sterilization. ``` The factors in determining scaffold design include: • natural or synthetic or composite • architecture, porosity, bulk form • stability and resorption rate • composition • bioactivity • strength • manufacturability • sterilization ```

Question 64

Describe two concerns with the use of extracellular matrix scaffolds and materials?

Answer 64

TRESCO 1. Immunogenecity-recognizes that it's foreign, generates response 2. degrades quickly- macrophages are activated and are degraded by FBR

Question 65

Describe how you would create a tissue w/ more than one function and cell type

Answer 65

``` TRESCO: Seeding Scaffolding Bottom-Up or Modular Approach -cell sheets+aggreages+cell laden modules+cell printing -module assembly -engineered tissue ```

Question 66

dif between glass and ceramics

Answer 66

Glass is amorphous in structure and is so brittle