Samenvatting
Biomaterials summary lecture
- Vak
- Biomaterials 1
- Instelling
- Rijksuniversiteit Groningen (RuG)
Biomaterials summary lecture
[Meer zien]Voorbeeld 2 van de 13 pagina's
Voorbeeld 2 van de 13 pagina's
In winkelwagengesponsord bericht van onze partner
Verkoper
Volgen
Voorbeeld van de inhoud
Group 1 (Water contact angle)- Quantative measurement (determine wettability of a surface by water).
- Indication of hydrophilicity (smaller angle indicates hydrophilic surface)
- Wetting/ non-wetting (complete not wetting (180 degrees) complete wetting (90)
- Static contact angles (boundary is not moving)
- Dynamic contact angles (no stationary contact angles, 2 angles can be distinguished
(picture)
- Factors to consider (roughness, heterogeneity, purity of solvent etc.)
Group 2 (Ellipsometry)
- Measures thickness and optical constant of thin films, with high
precision. It measures the change of polarization upon reflection or
transmission in comparison to a model.
- Characterize composition, roughness, thickness etc.
- Different fields use this
- Advantages: measures at least two parameters of each wavelength & measures an
intensity ratio instead of intensities.
Elliptical polarization of light is used.
Group 3 (Atomic force microscopy)
Sharp tip attached to a cantilever(silicon) which is attached to a z-piezo
(nanometer range accuracy)
Bending of cantilever (by repulsive energy) changes the direction of the laser
beam
Feedback loop: variation surface height and results in photodiode
Contact AFM:
Simple
Strong repulsive forces
Deformation or damage to surface
Easy to interpret
Non-Contact AFM:
AKA. Dynamic force microscopy
5-15 nm above surface
No deformation
Amplitude to determine surface
Time delay in feedback loop (disadvantage)
Group 4 (Laser scanning confocal microscopy)
Capabilities of CLSM
- Focus on a single focal plane within the specimen achieving sharp images
- From these single planes a 3D image can be obtained (stack sliced images)
- -> Provides structural and organizational information about cells and tissues
Advantages of CLSM
Compared to widefield fluorescence microscopy
- Control over the depth of field (because uses specific wavelengths)
, - Reduction of information that is not in the focal plane
- Allows to slice thicker specimens
Compared to TEM
- 3D imaging (TEM doesn’t allow this)
- Easier specimen preparation
Compared to SEM
- No need for vacuum condition (with CLSM)
- More detail, not only surface (CLSM can give more than only surface)
Compared to AFM
- No risk of tip interfering with specimen for CLSM
Group 5 (Dynamic light scattering)
- Technique in physics used to determine the size of (macromolecules)
particles down to 1 nm in diameter. The basic principle of DLS: 1. The sample
is illuminated by a laser beam and the fluctuations of the scattered light are
detected at a known scattering angle (θ) by a fast photon detector.
Basic principles
- Brownian motion: particles are constantly colliding with solvent molecules collisions
cause a certain amount of energy to be transferred – induces particle movement
- Smaller particles are moving and diffusing at higher speed than larger particles
- The relation between the speed of the particles and the particle size is given by the
stokes-Einstein equation – the speed of the particles is given by the translational
diffusion coefficient D – Requirement: particles move solely based on Brownian
motion -> no sedimentation
- Size limits: 1. Upper size: sedimentation 2. Lower size: signal-to-noise ratio
Advantages and disadvantages
Advantages:
● non-invasive, fast, and automated
● modest development costs
● can analyze samples containing broad distribution of species with different molecular
masses
● can detect small amounts of higher mass species (<0.01% in many cases)
suitable for molecular weight determination and size measurements of molecules in the
range of 10µm to less than 1 nm
● can also obtain radius of gyration and the translational diffusion coefficient
Disadvantages and Limitations:
● highly sensitive to solvent viscosity and temperature
● low resolution method ⇒ cannot differentiate between closely related molecules (e.g.
monomer and dimer)
● can only analyze liquid dispersion, whereas laser diffraction is effective for dry powders
too
● presence of large aggregates significantly affect the measurements
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper annerixtvanderwal. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €5,49. Je zit daarna nergens aan vast.
Is Stuvia te vertrouwen?
4,6 sterren op Google & Trustpilot (+1000 reviews)
Afgelopen 30 dagen zijn er 84251 samenvattingen verkocht
Opgericht in 2010, al 14 jaar dé plek om samenvattingen te kopen