Natural Polymers, Polysaccharide, & intro to Hydrogels Flashcards
What are the 4 characteristics of natural polymers?
- environmentally friendly
- emit low greenhouse gas
- low cytotoxicity
- biocompatible
What are the 6 sources for natural polymers?
- plants
- crustaceans
- animals
- humans
- microbials
- fungi
Where do polysaccharides mainly come from?
plants
What are polysaccharides?
long polymer chains composed of monosaccharide units bound together by glycosidic linkages
What is glucose and where does it come from?
simple sugar and comes from plants and algae
What is starch composed of?
30% amylose-linear and 70% amylopectin-branched
What are the 2 properties of starch?
- insoluble in COLD water
- hygroscopic - absorbs moisture from air
hygroscopic
absorbs moisture from air
What are the 4 applications with starch?
- bone replacement implants
- bone cements
- drug delivery
- tissue scaffolds
What sea animals results in abundant crustacean waste materials?
- lobsters
- crabs
- shrimps
What does chitin come from?
the processed shells and heads of crustaceans
What is chitin?
most important component of crustacean and insect exoskeletons or the cell walls of some bacteria and fungi (ex. mushrooms).
1. exoskeletons of crustacean and insects
2. cell walls of some bacteria and fungi
Chitin is a __________________ structure
highly crystalline structure
What are the 3 properties of the chitin structure?
- strong
- rigid
- linear
Chitin is soluble in concentrated ________________
acidic solvents
ex.
1. H3PO4
2. HCl
3. H2SO4
4. amide/LiCl
Chitin has trouble dissolving in common _____________
common organic solvents
ex.
1. DMSO
2. DMF
3. DCM
4. NMP
What is the disadvantage of chitin being insoluble in common solvents?
causes difficulty with processing
Chitosan is derived from?
Chitin
What groups in chitosan chains facilitate chemical modification?
amino and hydroxyl groups
What two things are known to affect the properties of derived materials?
- degree of deacetylation
- molecular weight
What are the 10 properties of chitosan?
- antioxidant
- hemostatic
- immunity enhancing
- anti-microbial
- analgesic
- biocompatible
- biodegradable
- almost water-soluble
- anti-tumor
- chelating
What medical issues does chitosan help reduce the time for?
- time of wound healing
- rebuilding connective tissue
Describe the anti-microbial activity of chitosan
- inhibits mRNA and protein synthesis via penetration of chitosan into the nuclei of the microorganism
- formation of an exterior barrier which deprives bacteria from nutrients and growth
- cationic charge interferes with negatively charged bacteria
What two types of chitosan might be useful in tumor growth prevention?
- low-molecular weight, water-soluble chitosans
- oligochitosans
How does chitosan prevent tumor growth?
partly through enhancing cytotoxic activity against tumors as an immunomodulator
chelation
ability to absorb metal ions
what natural polymer has the highest chelation rate?
chitosan
What applications is chitosan’s high chelation rate used for?
- water filtration
- removal of dyes, etc.
What can be enhanced for the chelation effects of chitosan?
- absorption
- selectivity
Modifications in what groups cause chemical and physical changes for chitosan?
amine and hydroxyl groups
What metals can chitosan absorb?
Zn, Hg, and Ag
where Ag is a disinfectant or bactericide
Changing what effects absorption for chelation rate of chitosan?
pH
What two things have the properties of disinfectants and bactericides?
chitosan and metal ions (Zn, Zr, and Ag)
What are the non-medical uses for chitosan?
- cosmetic moisturizers
- coating for fruits and vegetables
- water treatments (filters)
Pullulan is a _______ _______ polysaccharide of ____________
linear homopolysaccharide of glucose
Where does pullulan mainly come from?
strains of fungus Aureobasidium pullulans
Production process for pullulan is complicated because _________________________.
removal of melanin from Aureobasidium which adds to the production cost.
Pullulan has a very high __________
molecular weight
The flexibility of pullulan allows for it to form ________and ________.
fibers and distinct films.
List the 8 properties of pullulan
- very flexible
- hydrophilic - dissolves in water
- non-hydroscopic
- adhesive
- oxygen impermeability
- odorless, tasteless, and edible
- transparent
- low viscosity
What does low viscosity for pullulan mean?
it is stable when exposed to heating at high temperatures and changes in pH
4 Methods to alter properties of pullulan and results:
- esterification or etherification - to reduce water solubility
- hydrogenation - to increase stability
- carboxylation - to increase solubility in cold water
- co-polymerization - to change function and abilities
What are the medical applications of pullulan?
- drug delivery - coating for sustained release
- wound healing
- vaccines
- tissue engineering
What are the 2 limitations with pullulan?
- mechanical properties are weak due to its hydrophilic nature
- high cost of production limits its usage
What are hydrogels?
water-swollen, cross-linked polymer network produced by simple reaction of one or more monomers
What is the unique property of hydrogels with water?
swell and retain significant amount of water but does not dissolve in water
What causes the unique property of hydrogels with water?
hydrophilic functional groups attached to the polymer backbone
Why don’t hydrogels dissolve in water?
their crosslinking does not allow them to dissolve
What does the structure of hydrogels mimic?
body tissue
