C2-HC 9 Flashcards
Biomaterials:
Biomaterials=
- Materials exploited in contact with living tissues, organisms, or microorganisms.
Non-viable material used in a medical device, intended to interact with biological systems in order to perform with an appropriate host response in a specific application. (There are multiple definitions.)
Classification of biomaterials:
- Artificial/synthetic origin (manmade)
○ Ceramics
○ Metals
○ Polymers- Composites: a mix of biomaterial and natural origin
- Natural origin
Biopolymers: collagen, alginate, hyaluronic acid
Extracellular matrix (ECM) functions:
Extracellular matrix (ECM)= a 3D-network consisting of extracellular macromolecules and minerals that provide structural and biochemical support to the surrounding cells. Functions: - Cell adhesion - Cell-cell communications - Differentiation Provides support for tissues
Polymers: definition & function
Polymers= large molecule consisting of repeating units (monomers).
polymers (and esters) are used for making stiff materials like scaffolds and micro/nanoparticles.
Polymerization:
Polymerization= process of linking together monomers.
Classification of polymers:
Classification:
- Homopolymer= single type of repeat unit
- Copolymer= 2 or more types of repeat unit
○ Random copolymer: monomers are randomly distributed in the polymer.
○ Alternating copolymer: monomers are alternated in the polymer.
○ Graft copolymer: main polymer covalently bonded to one or more side chains.
○ Block polymer: two or more homopolymer subunits linked by covalent bonds
Number of averaged molecular weight (Mn): & Weight averaged molecular weight (Mw): & Polydispersity index (PDI):
Number of averaged molecular weight (Mn)= the average of the molecular weights of individual chains.
&
Weight averaged molecular weight (Mw)= a bigger molecule contains more of the total mass of the polymer sample than the smaller molecules do. Important: the heavy molecules count more. Because: the longer the polymer, the more they contribute to the material properties.
If all your polymers are of the same length, than Mn and Mw would be equal.
&
Polydispersity index (PDI)= Mw/Mn (typically a value of 1.1-2.0). This is the with/ spread of the curve.
Advantages of natural polymers:
Advantages of natural polymers:
Biocompability
Cell-controlled degradability
Intrinsic cellular interactions
Disadvantages of natural polymers:
Disadvantages of natural polymers: Large batch variations Narrow/ limited range of mechanical properties Difficult to process Immune response
Advantages of synthetic polymers:
Advantages of synthetic polymers:
Precisely designed
Less batch-to-batch variations
Disadvantages of synthetic polymers:
Disadvantages of synthetic polymers:
Limited biogedrability
Use of toxic chemicals
Limited cell adhesion or proliferation
Natural polymers can be categorized into 3 groups:
Natural polymers can be categorized into 3 groups:
- Polysaccharides: example is alginate. Its popularity stems from how easily it can complex with CaCl. This way you already have a hydrogel just by mixing some calcium ions. - Proteins: based on amino acids linked together. Found in a multitude of tissues (e.g., collagen, gelatin, esastin, fibrin). - DNA and RNA: available in less quantity. Long polymers that can also be used to construct biomaterials.
Hydrogel:
Properties of a hydrogel:
- They have a highly porous and hydrophilic structure (they contain a lot of water!) that allows the free diffusion of oxygen, metabolites and nutrients, making contact with biological tissues highly favourable.
They are able to encapsulate in their porous structure water-soluble drugs (proteins, peptides, nucleic acids), cells, hydrophobic structures, etc.
Hydrogel:
increase of crosslink density > increase/decrease permeability?
increase of crosslink density > decrease permeability (than it is difficult for molecules to diffuse in and out)
Hydrogel:
increase of crosslink density > increase/decrease stiffness?
increase of crosslink density > increase stiffness
