Biopolymers Flashcards
Why is Cellulose used as a biopolymer?
Beta-1,4-linked glucose, more simple polysaccharide
Hydrogen bonding network create a very stable structure, but number of free hydroxyls make it amenable to chemical alteration
includes wood pulp, viscose rayon, cotton
Why is Bacterial Cellulose used as a biopolymer?
Produced by some bacteria
BC/fibroin - BC can be made into a scaffold but does not promote cell attachment, the added silk fibroin assists in attachment
why are proteoglycans used as a biopolymer?
Proteins attached mostly via O-linkage to polysaccharides called glycosaminoglycans (GAGs, make up 95% of molecule). Made up of disaccharide repeats of amino acid and uronic acid sugar, often heavily sulphated
GAG component determines function. Function as joint lubricants, structural components of extracellular matrix, mediate adhesion of cells to extracellular matrix, bind factors that stimulate cell proliferation
Produced by almost all mammalian cells.
If bound to lots of water, it forms hydrated gel able to withstand high compressive loads
Why is Hyaluronan (hyaluronic acid) used as a biopolymer?
Carbohydrate polymer. Lacks covalently linked peptide unlike other GAGs
Hyaluronan is used in many forms for a variety of conditions e.g. eye drops, face creams, serums. HA has anti-adhesion properties
Ubiquitous (found everywhere) in connective, epithelial and neural tissues, especially in joints and skin. Made commercially by fermenting bacteria. Main lubricant in synovial fluid
Why is Pectin used as a biopolymer?
4 main structures found in different proportions dependent on species of origin - Homogalacturonan, xylogalacturonan, rhamnogalacturonan I and II
Homogalacturonan (HG) – homo-polymer of galacturonic acid, can be decorated with methyl esters or O-acetyl esters.
Calcium ions can cross link HG strands through carboxylic acids, this polymerization leads to gelling, gel strength is proportional to number of cross links
Gelling – gel strength is influenced by concentration of calcium ions (increasing concentration will increase gelling speed and strength up to a certain point, increasing above certain concentration actually decreases gelling properties) and degree of methylation
Crosslinking can be through a number of chains
What is a DNA hydrogel?
Assembly of DNA based macrostructures can create gels with excellent biocompatibility, biodegradability, basic programmability, catalytic activity, therapeutic potential and molecular recognition and bonds
Composite hydrogels have different properties, different composites can be created such as DNA-protein, DNA-carbohydrate, DNA-acrylamide etc.
DNA gels can be used for in vitro transcription, producing proteins in highly regulated ways
Why are Protein Biocomposites used?
Some Biocomposites are created naturally e.g. collagen or elastin
Many proteins have repeating sequences that lead to consistent structure e.g. elastins, collagens, silks, keratins
Combinations of proteins can generate new multifunctional protein composite systems with tailored properties.
Tailorable properties include mechanical, electrical, electromagnetic, optical, chemical and thermal applications.
For example, a rigid protein (like silk) can be mixed with a soft protein (like tropoelastin) to mimic a range of elasticities of different human tissues.
What are 3 methods of polymerisation?
Addition polymerisation - radical cationic, anionic, coordination catalytic, block copolymerisation
Condensation polymerisation - water molecule is formed from each chain extension
RAFT (reversible addition-fragmentation chain transfer) - one of the most commonly used methods now. Allows the synthesis of polymeric architectures with predictable molecular weight, low molar mass dispersity
