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Biomaterial > Biomaterials > Flashcards

Biomaterials Flashcards

1
Q

Why are biomaterials needed and important?

A

Because they can help with cartilage damage, hip fracture, drug delivery and wound dressing. The market for this is very big.

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2
Q

What is a biomaterial?

A

A material intended to interface with biological systems to evaluate, treat, augment or replace any tissue, organ or function of the body

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3
Q

Mention some different biomaterials.

A

Polymers, Metals, Ceramics, Composites

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4
Q

What is the definition of biocomatibility?

A

The ability of a material to preform with an appropriate host response in a specific application

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5
Q

What are Standards and what are they used for?

A

Standards are a document with guidelines that are to be followed. It is a consensus-built, repeatable way of doing something.

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6
Q

What are some factors that are evaluated for medical devices?

A
  • In vitro cytotoxicity
  • Immune response
  • Biodegradation
  • Interaction with blood
  • Systemic toxicity (acute and chronic)
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7
Q

Explain the different In vitro cytotoxicity tests

A
  • Direct contact test: determines if a material itself has potential to by cytotoxic
  • Indirect contact test: determines if material itself has potential to release agents that may be cytotoxic
  • Extraction test: material is extracted at 37 °C with culture medium and the extract is added to cell culture. Determines if a material extract has the potential to cause cell morphology change and/or lysis
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8
Q

Why can’t in vitro tests replace in vivo tests.

A

Because the in vitro tests do account for coagulation, inflammation, immune response, interactions with ECM. These aspects are very important for determining if the biocompatibility of a material.

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9
Q

Why are protein-cell-biomaterial interactions important?

A

Because cells don’t interact with a naked surface. There is often an adsorbed protein layer that mediated cellular behavior.

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10
Q

What properties are protein adsorption influenced by?

A
  • Protein properties: size, shape, the distribution of hydrophobic and hydrophilic groups, and the charge distribution
  • Surface properties: the topography of the surface, distribution of hydrophobic and hydrophilic groups, and the charge distribution
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11
Q

What is the driving force for protein adsorption?

A

The increase in entropy (disorder).

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12
Q

What can be the effects of adsorption of a protein to a biomaterial surface on the biological activity of the protein, compared to the activity in solution?

A
  • Partial dehydration of protein and material surface
  • Redistribution of charged groups in the interface
  • Conformational changes in the protein molecule
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13
Q

Mention one difference between hydrophobic and hydrophilic surfaces.

A

Hydrophilic surfaces generally allow reversible proteins adsorption

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14
Q

What factors determine the rate of protein diffusion to a biomaterial surface?

A

Protein concentration and diffusion coefficient

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15
Q

What is the difference between surface and bulk erosion?

A

Bulk erosion: decrease in molar mass and mechanical properties

Surface erosion: Significant mass loss while the MW and mechanical properties are unchanged

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16
Q

What happens when a biomaterial is implanted?

A
  • The immune response is activated
  • The Coagulation system is activated
  • The Complement system is activated
17
Q

What are the consequences of the foreign body response?

A
  • A fibrous capsule froms around the implant that may interfere with the implant
  • Macrophages secrete enzymes, acids and ROS that may degrade the biomaterial
18
Q

Why is the surface of a biomaterial important?

A

The surface properties determine the adsorption if proteins and cell interactions, therefore influencing the biocompatibility.

19
Q

Mention some methods for surface modification.

A
  • Wet chemistry: PEO (hydrophobic) inhibit all protein and cell interactions with the surface
  • Gas plasma treatment: Gas at low pressure is discharged by high frequency radio waves. Generates reactive species that modifies the surface.
  • Silanization
  • Self-assembled monolayers
20
Q

What are some methods for surface analysis?

A

AFM, SIMS, XPS, water contact angle

21
Q

What are some advantages of using additive manufacturing?

A
  • Rapid fabrication
  • Customized design
  • Low cost
  • Ideal low volume processing
22
Q

Describe 3 different additive manufacturing techniques.

A

Stereolithography: uses a laser to cure a photosensitive resin layer to create a 3D structure.

Extrusion-based AM: Creates a #D structure by extruding material through a nozzle layer-by-layer. There is a liquid to solid transition of the material.

Fused deposition modeling: Extruding a molten layer of material to create a 3D object

23
Q

What is the definition of a hydrogel?

A

Insoluble network of polymer chains and/or molecules that swell in aqueous solutions

24
Q

What is the difference between physical and chemical crosslinking in hydrogels?

A

Physical crosslinking: non covalent bonds that are non permanent. Can be hydrogen bonds, guest-host complexes.

Chemical crosslinking: covalent bonds that are permanent.

25
Q

What are some applications of hydrogels?

A

Recapiulate ECM properties, Cell carriers, Drug carriers

26
Q

Give some examples of biomedical uses for hydrogels.

A
  • Scaffolds in tissue engineering
  • Contact lenses
  • Sustained-release delivery systems
  • Lubricating surface coating
27
Q

What is the definition of bioink?

A

Cells containing material for 3D printing. Hydrogels are well suited for bioink formulations

28
Q

What are some disadvantages of autografts?

A
  • Facilitates bone ingrowth
  • Takes time
  • Limited supply
29
Q

What is the definition of osteoconduction?

A

Grafting materials form a framework outside the graft during the formation of the new bone. The bone grows on a surface

30
Q

What is the definition of osteogenesis?

A

The formation of bone

31
Q

What is the definition of osteoinduction?

A

The process by which osteogenesis is induced. Cells within the grafting material are converted into bone-forming cells to form the new bone

32
Q

What are some alternatives for bone grafts?

A
  • Synthetic scaffolds w/wo stimuli
  • Induction: BMPs or matrix derivatives
  • Cell-based TE: fresh bone marrow, cultured MSCs.
33
Q

Why do cell-based RM fail?

A

The cells die in big implants. Cells do nor survive in an environment without blood

34
Q

What are some guidelines that regulate the biomaterials biocompatibility from a cell-biomaterial interaction?

A
  • Specific adhesion proteins and cells receptors
  • Signal transduction
  • Cell differentiation
  • Tissue development
  • Host immune response mechanism
35
Q

What are som application of interfacing and modelling?

A
  • Regenerative medicine
  • Drug delivery
  • Gene therapy
  • In vitro tissue and disease models
36
Q

What are some advantages to 3D cell cultures compared to 2D?

A
  • Natural gradient formation
  • Physiologically relevant mechanism forces
  • In vivo-like cell morphology and gene expression (mimics the human relevant microenvironment)
37
Q

What are the ideal chemical, physical and biological characteristics of a biomaterial for engineering of bone tissue?

A
  • Biocompatibility
  • Mechanical properties
  • Porosity
  • Degradable
  • Bioactivity
  • Chemical stability

Biomaterial (2 decks)

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