Biomaterials and scaffolds Flashcards
what is biomaterials?
- a nonviable material used in a medical device, intended to interact with biological systems.
- a material intended to interface with biological systems to evaluate, treat augment or replace any tissue, organ of function of the body.
what are the 4 main types of biomaterials?
- polymers
- cermaics
- semiconductor materials
- metals
what are polymers used for?
- skin/catrilage
- ocular implants
- drug delivery devices
what are ceramics used for?
- bone replacements
- heart valves
- dental implants
what are semiconductor materials used for?
- biosensors
- implantable microelectrodes
what are metals used for?
- dental implants
- orthopedic scres/fixation
what is the most common polymer used for drug delivery?
polyethylglycol
why are biosensor development needed?
want sensors that can detect changes in the environment which are coated in a good material that allows diffusion but prevents accumulation
why is titanium used in bone?
bioactive- bone will grow onto the surface of it
what are the 4 main things that need to be considered during biomaterial selection?
- mechanical
- biological
- chemical
- optical/electrical
- regulatory constraints
give 6 material selection parameters
- mechanical
- biocompatibility
- water absorption
- diffusion
- biostability
- degradation properites
what are the 3 main polymers used and why?
PLLA, PGA and PCL- they have FDA approval
what is a problem with PCL?
doesn’t degrade very well- hydrophobic
what is wrong with the 3 polymers that are used most?
they dont degrade in a linear way- get rapid transfer of mechanical load onto th new tissue. You also get a lot of debris- sterile inflammation
what are some simple biological parameters can control what happens in the cell?
- the surface roughness can determine how stem cells differentiate
- surface charge
- stiffness
why do we need scaffolds in biotechnology ? (4)
- Protect the cells.
- Enable delivery of cells to the area of need: gels maybe
- Retain the cells in the area of need.
- Modulate the cellular response.
what is the basic principle of tissue engineering? what is the potential problem with this model?
- cells from a biopsy
- monolayer cell culture
- expanded cells
- culture of a 3D polymeric scaffold
- generation of a graft
(can be too expensive and time consuming)
what are the three elements of tissue engineering/ regenerative medicine?
scaffold: porous, absorbable synthetic and natural biomaterials (collagen bs polygylocolic acid)
- cells (autologous or allogenic): differentiates cells of same type as tissue, stem cells
regulators: growth factors or their genes, mechanical loading, static versus dynamic culture
how can scaffolds be involved in matrix?
before it is absorbed a scaffold can serve as a matrix for cell adhesion to facilitate/“regulate” certain unit cell processes (e.g., mitosis, synthesis, migration) of cells in vivo or for cells seeded in vitro.
– the biomaterial may have ligands for cell receptors (integrins)
– the biomaterial may selectively adsorb adhesion proteins to which cells can bind
what are the 7 main roles of a scaffold?
- the scaffold serves as a framework to support cell migration into the defect from surrounding tissues; especially important when a fibrin clot is absent.
- serves as a delivery vehicle for exogenous cells, growth factors, and genes; large surface area.
- before it is absorbed a scaffold can serve as a matrix for cell adhesion to facilitate/“regulate” certain unit cell processes
- may structurally reinforce the defect to maintain the shape of the defect and prevent distortion of surrounding tissue.
- serves as a barrier to prevent the infiltration of surrounding tissue that may impede the process of regeneration
- Thescaffoldsmayservetosupport/carrycells grown ex vivo back into the implant site to migrate off the implant. Or:
- To entice cells from the surrounding tissues onto the scaffold to fill the defect.
what factors prevent regeneration?
- size of the defect: large bone defects will not regenerate easilyy
- collapse of the surrounding tissue into the defect: periodontal defects. solution is membranes for guided tissue regeneration- keep soft tissue out of the way while the bone comes back
- excessive strains in the reparative tissue- unstable structures that require fixation
what are 3 synthetic scaffold materials?
– Hydroxyapatite
– Calcium carbonate
– Calcium phosphate
what is a scaffold material used that is natural?
natural bone mineral - HA
what is a sinus lift? what is the problem with the granules here?
lift gum up- put an implant of lots of material such as synthetic or natural granules (bone chip maybe) and after 6 month hopefully the bone will grow in and you can put an implant in. They take up lot of room in the implant
