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Quantum dots (QDs)
Quantum dots are semiconductor nanocrystals with size 3-10 nm
that show excellent optical properties.
They produce an intense monochromatic fluorescence when excited by a wide range of radiation.
This characteristic combined with their ability to bound to organic
molecules such as DNA, RNA and proteins makes them ideal candidates
for the development of novel detection techniques.
Materials required for Quantum dots-probe conjugation:
Quantum Dots, streptavidin, EDC, Borate buffer, biotinated probe
In a 1.5 ml microcentrifuge tube add 50 μl of QDs,
400 μl of Borate buffer,
96 μl of streptavidin and 11,4 μl of EDC
Stir gently for 1-2 hours at room temperature
Transfer the solution to a centrifugal ultrafiltration unit (100 kDa cutoff).
Centrifuge at 4.000xg for 10 min
Repeat for at least 5 buffer exchanges using borate buffer to remove any excess unbound protein
Elute the solution from the filter with 200 μl borate buffer
and add 64 μl biotinated probe
Incubate the solution for 15 min at room temperature
Transfer the solution to a centrifugal ultrafiltration unit (100 kDa cutoff)
Wash 3 times with borate buffer
Elute the QDs-probe from the filter with 500 μl borate buffer
Materials required for magnetic beads-probe conjugation:
Magnetic beads conjugated with streptavidin, PBS, biotinated probe
In a 1.5 ml microcentrifuge tube add 200 μl magnetic beads,
place the tube on a magnet for 1-2 min,