Simon Pope Flashcards
How to aid cytoplasmic staining?
Use fluorinated complexes. Aids with going across the cell membrane due to the lipid loving nature of fluorine (cell membrane is full of lipids).
or cyclohexyl groups
How to aid nucleus staining?
Planar aromatic systems encourage DNA intercalation. aids transport to the nucleus and allows it to bind to high conc of DNA.
Why long lifetimes can improve image contrast?
Long luminescence lifetime means autofluorescence can be avoided. Autofluorescne has a short life time so a time delay before detection can avoid it.
Features of ligands that allow water solubility?
- Ionic species
- Electronegative atoms that form H-bonds
Why Near IR emission wavelengths helpful in optical bio-imaging?
Biological tissue is much more transparent to Near-IR wavelengths
Example that produce these sorts of wavelengths are Yb(III) and Nd(III).
Why DOTA is well suited to coordinate to lanthanide ions
8 donar macrocyclic species
- Chelate and macrocyclic effect
- stability
- No leaching of metal ion
How solvent polarity effects emission wavelength?
- An increase in solvent polarity will stabilise the excited 3MLCT state. i.e. lower energy and higher wavelength.
- This can be useful in biological imagine as there will be a change in emission upon change of solvent polarity.
Why Mn species are non emmisive?
The Delta Energy is too small (T2g-eg) and therefore the Eg* orbital will be lower in energy than the 3MLCT. Energy will therefore be lost by vibrational processes.
Advantages of luminescence metal complexes?
- High sensitivity and low cost
- Specific starting and multichannel detection
- emission in UV-VIS-IR region
- Can be responsive to environment
Why is it attractive to have bi-modial imaging agents?
- Only one drug needs to be delivered into patient instead of two
- MRI imaging works on whole body but at low resolution
- Fluorescence give high resolution at cellular level
Importance of large stokes shift and long luminescence lifetime
-Large stoke shift avoids autofluorescence. If the stoke shift is too small “self-quenching” will occur. Re-absorption by neighbouring molecules and loss of intensity.
- Long luminescence life time allows the application of time-gating techniques
- autofluorescence has a short lifetime, so allow a time delay to avoid it.
Bathochromic shift
A shift too higher wavelength, lower energy. (red shift)
-Could increase conjugation or add EWG.
Why lanthanide emission spectra are line like?
4f orbitals a very contracted and close to the nucleus. They are uneffected by ligand field and therefore the energies are insensitive to the ligands and solvent. Only intensity of the peak is changed.
How to target mitochondria cells
- Include a chloromethyl group in complex
- There is a high conc of thiols in mitochondria
- Thiol reacts with chloromethyl to form adduct and increases the conc of fluorophore in cell
How respiratory activity in cells could be indicated
The quantum yield of a 3MLCT is sensitive to the amount of dissolved oxygen in the environment. The more oxygen present the more quenching (non radiative decay) will take place and therefore the intensity(quantum yield) will, be lowered.
