Imaging

Question 1

Contrast

Answer 1

The ability to distinguish stuff (quantitative)

Question 2

Contrast-enhancing techniques

Answer 2

Brightfield, Phase contrast, DiC, Hoffman modulation, darkfield, polarized light

Transforms differences in the cell into differences in brightness

Question 3

Bright-field illumination

Answer 3

Background very bright, specimen dark. Refractive index of cells/biological material just slightly higher than water

Question 4

Dark-field illumination

Answer 4

Only light scattered by specimen visible. Dark background, bright specimen.

Question 5

Resolution

Answer 5

How fine you can see (qualitative)

Question 6

Phase-constrast illumination

Answer 6

Thick part of cells appear dark cause higher viscosity. Restricted to thin specimens

Question 7

DIC

Answer 7

Better resolution than bright field and PC.

Question 8

Fluorescence

Answer 8

Photon excites electron with some energy P, electron drops down to ground state and emits some energy E which can be detected

Question 9

Absorption-Emission fluorescence spectra

Answer 9

Absorption graph show higher energy –> shorter wavelength than the emission graph.

Question 10

Stokes shift

Answer 10

Overlap of adsorption and emission graphs

Question 11

Why fluorescence?

Answer 11

High contrast, easy labeling, imaging of living cells

Question 12

Green fluorescent protein

Answer 12

Link to protein you want to express. If protein is created so is GFP and you can see if it worked.

Question 13

Widefield microscopy

Answer 13

Fast and efficient, but low contrast compared to confocal point microscopy

Question 14

Brownian motion

Answer 14

Random nanoparticle motion caused by temperature fluctuation of surrounding molecules

Question 15

Confocal microscopy

Answer 15

Focusing of different points of the specimen reducing background noise, allowing for high resultion images that can be reconstructed into 3d visualizations.

Question 16

Gaussian fit function

Answer 16

Intensifies bright pixels and darkens dark pixels, smoothening up pixelated images allowing for specific characterization and localization.

Question 17

FLIM

Answer 17

Fluorescence Life-time Imaging Microscopy

High resolution cell fluorescent imaging. Image contrast is based on excited state life-time, t, variations across the sample. The higher t, the fewer photons that can be detected from that point.

Question 18

TIRF

Answer 18

Total Internal Reflection Fluorescence

Fluorescence of samples close to a surface. Ideal for studying molecules/cells/bacteria attached to a surface or membrane.

Question 19

QCM-D

Answer 19

Quartz Crystal Microbalance with Dissipation

Mechanical technique that measures the mass change at the quartz sensor including the water coupled to the oscillation.

Question 20

Gold nanoparticles for cancer treatment

Answer 20

Nucleic acid delivery, drug delivery, photothermal theraphy (proposal A)

Question 21

Plasmons

Answer 21

In simpler terms, plasmons are like synchronized movements of electrons in metals when they interact with light,

Question 22

Key features of nanoplasmic structures

Answer 22

Field confinement - Plasmons allows light to be focused down to molecular dimensions

Field enhancement - enhancement of optical fields near metal nanostructures

Tunability of the enhancment effects in space and wavelength

Question 23

FRET

Answer 23

Förster Resonance Energy Transfer

Measures distance between flourophores in molecules. Emission energy from one flourophore becomes absorption energy to another and so on. Used to study protein dynamic, folding, interactions.

Question 24

SMLM

Answer 24

Single Molecule Localization Microscopy

Obtains information beyond diffraction limit (200 nm) by pinpointing positions of single fluorophores. Resolutions down to a few nanometers

Question 25

SMLM: Blinking

Answer 25

Fluorophores in samples emit fluorescence briefly and spontaneously. At any given time, most fluorophores are dark and only a few of them are blinking, allowing to localize them by PSF:ing their position. The blinking of fluorophores is aquired as a long sequence of thousands of frames, in order to localize millions of fluorophores.

Blinking techniques are, PALM, STORM