Ceramic Processing
Glass ceramics begin as glasses but become ____ ceramics during processing
polycrystalline
What are the two main methods/categories of sterilization
Physical methods: heat, pressure, filtration
Chemical method: gas and liquid sterilants
For bulk material characterization imaging, what technique would you use?
Light microscopy or SEM
What is the difference between adsorption and absorption?
Absorption: penetration of molecules into the bulk of a material
Adsorption: adhesion of molecules to a solid surface
Name 3 assays that can be used to measure the amount of absorbed protein (directly or indirectly)
Bonus: Name the assays that help determine the type/identity of the adsorbed protein
ATR-FTIR, AFM, HPLC, QCM, Colorimetric and Fluorescent Assay
Bonus: SIMS, ELISA, Western Blotting
What is the resulting piece of casted ceramic called, and two processes does to go through to form the final product?
Green ware, which then goes through drying and firing
Name two heat sterilization techniques; List their advantages and disadvantages
Dry-heat sterilization
Steam sterilization
Adv: simple, quick, fairly effective, no toxic residue
Dis: Not suitable for heat/moisture sensitive
hydrolytically degradable polymers
has to contact surface
Bulk material characterization:
What technique provides chemical information
Bonus: What techniques provide thermal and molecular weight information
Mass spectrometry
Bonus: DSC (thermal), HPLC (MW)
What material surface properties are most important to protein adsorbtion?
Charge, hydrophobicity, topography/roughness, steric concerns
Explain how ELISA works
The specific binding of antibodies may be linked to a molecule which enabled by colorimetric or fluorescent detection, commonly the primary antibody is not labeled, the secondary antibody is and it makes ELISA more specific.
Powder processing of ceramics result in what characteristic?
Reduced porosity
Name the different radiation sterilization techniques, what are their advantages and disadvantages?
UV sterilization (poor penetrating power), gamma ray sterilization, x-ray sterilization, electron beam sterilization (lower penetration depth)
Adv: High penetration depth (gamma ray, x-ray), quick, fairly effective, no toxic residue
Dis: low penetration (E-beam), some polymers are degradable, high capitol cost
What surface characterization techniques give you chemical information
Bonus: Mechanical properties of bulk materials can be characterized using:
AT-FTIR, XPS/ESCA, Raman (certain setups), Secondary Ion Mass Spectrometry (SIMS)
Bonus: Tensile, Compression, Shear and Bending tests
How does the dehydration of the surface (contribution to hydrophobicity) affect the adsorption in terms of entropy?
Hydrophobic areas coming together disorders water in the area, increasing entropy, and redistributing charges leading to adsorption of proteins due to fewer ion transfer from solvent is required.
Do you think that this adsorption profile was generated via QCM-D? Why or Why not?
Bonus: What other techniques that we’ve discussed so far would be best to use to generate this type of adsorption profile?
Most likely not; QCM-D measures the amount of absorbed protein (via absorbed mass), but cannot distinguish the between the two proteins in terms of identify
Bonus: ELISA, Western blotting or Mass Spectrometry (SIMS) would most likely be used
Which ceramic fabrication technique is likely to result in a high ultimate tensile strength: drain slip casting, hot isotactic pressing, or 3D printing?
Hot isotactic pressing produces less porous structures and would thus result in higher ultimate tensile strength
- Drain slip casting is generally used to produce structures with hollow structure
-3D printing is generally used to produce more porous and complex structures with weaker binding
Name the advantages and disadvantages of both EtO and Hydrogen peroxide plasma system sterilization
EtO:
Adv: low temp, excellent penetration depth, suitable for wide range
Dis: toxic/carcinogenic, time-consuming,
HP:
Adv: no toxic residue, good for heat/moisture sensitive
Dis: not suitable for some materials, limited clinical use
What surface characterization techniques can you use to characterize morphology/topography
Bonus: Name two other surface characterization techniques that show different important properties
TEM, SEM, SPM/AFM
Bonus: Contact angle analysis, and SPM/AFM
Protein stability and structure depends on
_____ ______
chemical compostion
What determiners of protein structure have the largest impact on protein adsorption to a material? Why?
Dehydration, redistribution of charged groups, structural rearrangement of the protein. All these three components play a role in protein adsorption due to their large effect on the Gibbs free energy.
Name the two different ceramic processing techniques that use glass and molds; Explain how they work
Pressing, pressure is applied to softened glass and placed in heated mold
Blowing, pressing happens first, then a jet of air forces soft glass to conform to mold
Consider a novel vascular stent made from a surgical grade steel. The stent has been coated with a novel polymer to help integration with native tissue and prevent further narrowing of the vessel. Would steam sterilization, ethylene oxide sterilization, or radiation sterilization be preferred for this device? Why?
Ethylene oxide would generally be preferred for sterilization of the coated stent. Recalling that polymers have lower melting temperatures than metals, steam sterilization would not be appropriate because it may melt the polymer coating. Although both radiation and EtO treatment may damage polymeric materials, this is often more of a concern with radiation. Therefore, the recommended method would be to sterilize the device with EtO and characterize both the metal and polymer components post-treatment to assure that no degradation has occurred.
Which characterization technique would you utilize to help estimate a polymer's affinity to the surface of your material
Contact angel analysis, SPM/AFM, SIMS
What is the relationship that protein concentration and surface affinity have to protein adsorption and what is the effect associated with it?
Surface affinity, which is reliant on size, charge, hydrophobicity, stability and unfolding rate, will ultimately supersede concentration because of an effect known as Vroman Effect
Explain the process of Western Blotting and the components of it.
Proteins are contained via gel electrophoresis, then treated with SDS, and loaded to a SDS containing PAAM gel and exposed to an electric field (SDS-PAGE), the larger molecules will migrate slow and they will separate by molecular weight, the gel is goes through blotting and blocked from non-specific binding. A primary antibody is added, and a labeled secondary antibody is added. A substrate is added to enable colorimetric detection