Tissue Engineering - Biomaterials III
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What are biomolecules and their use? What are two disadvantages to them?
Biomolecules are molecules such as proteins (VEGF, Insulin etc) thar are necessary to assemble cells. (There is no self-assembly understood)
Two disadvantages include the cost to produce these biomolecules and the half-life of the molecules.
What is an example of biomolecule delivery?
Biomolecules delivered in tissue engineering to assist tissue formation.
The biomolecule may be placed inside the scaffold or the cells that produce the biomolecule may be used.
What are some examples of controlled release systems?
- Scaffold/biomolecule integration
What are some benefits of nano-particles?
- Fairly easy preparation
- Good control over size and size distribution
- Good protection of the encapsulated drug
- Longer clearance times
What are some disadvantages of nano-particles?
- Extensive use of poly(vinyl alcohol) - PVA may have issues with toxicity
- General toxicity issues unknown
- Limited targeting abilities
What are types of nano-sized drug delivery vehicles?
- Nanosuspensions & Nanocrystals
- Solid Lipid Nanoparticles
- Polymeric Nanoparticles
These include: drug-enriched core, solid solution, drug-enriched shell
What are some aspects of polymer-based particle systems?
- Increase stability of volatile drug agents
- Produced relatively easily
- Vast source of chemistries available
- Many have engineered specificity both to the drug and the target - difficult to achieve with other carriers
- Drug-release profiles and triggering dependent on polymer structure.
What are some qualities of relevant polymers?
- Structure - mostly copolymers, combining different qualities of their parent polymers
What are some advantages of hydrogels?
- Benefits include:
- -closest analogue to living tissue
- -capable of binding large amounts of fluids and drugs including proteins
- -swelling ratio controllable by variation in structure (hydrophobic/hydrophilic ratio)
- -small changes in temperature, pH, electric/magnetic field can trigger large volume change/release of drug
- -in many cases, well defined release patterns
- -more difficult to characterize/predict behavior
- -not as many defined stoichiometric compounds
What are three methods of gene transfer?
- Viral vectors
- -retroviral vectors
- -adenoviral vectors
- Non-viral vectors
- Other methods
- -particle bombardment (gene gun)
What are some of the issues with naked DNA delivery?
- Not effective in vitro
- Inefficient in vivo
Works only certain tissues (ie muscle)
However, they are simple and inexpensive and plasmid delivery is posibly using hydrogels.
What would be an interesting use of biomimericty? What is biomimericetic materials?
Materials that are inspired from nature. Examples include the skin of the shark for it's properties and the structure of honeycombs.
The use of the honeycomb structure has been used for lightweigh and high compression applications. This may be beneficial for the use of loadbearing applications including humanbone. This would also allow for factors such as VEGF and PDGF to be embedded for vascularization.
What are three characteristics of skin and four functions of skin?
- -Poor conductor of electricity
- Functions of skin:
- -To protect the body from external insults
- -To contain all body fluids
- -To regulate body temperature
- -To protect from electrical current
What are two routes for penetration of transdermal drug delivery?
- Penetration includes
- -intercellular route
- -follicular route
What are the two mechanisms for transdermal drug delivery?
What are some advantages of transdermal drug delivery?
- Steady permeation of drug across skin
- Controlled drug delivery
- Good for acid and enzyme reactive drugs
- Minimum risk of side effects
- Limited toxic effects
- Easy drug administration
- Good for lipophillic drug molecules
What are some disadvantages and limitations of transdermal drug delivery?
- Possibility of a local irritation
- Allergic reactions are possible
- Risky for children
- Skin's low permeability
- Molecular size and polarity of drug
- Insufficient bioavailability
- Damage to a transdermal patch
(T/F) Polymeric systems have a great potential in drug delivery applications.
(T/F) Difficult characterization, expensive and long processes of synthesis and purification are major drawbacks of polymeric systems.
What are the three main elements of tissue engineering?
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