The research aims at finding out how the hydrocarbon chain lengths and functional groups of a ligand attached to a Quantum Dot affect its fluorescence. By maximising fluorescence, the research aims to enable earlier detection of cancerous tissue and hence increase a patient’s chances of survival.

 

Copper Indium Sulfide Zinc Sulfide Core-Shell Quantum Dots were synthesised before ligands of different lengths and functional groups were attached to them. The fluorescence of the samples was then measured using a plate reader. The samples were also sent for TEM analysis.

 

It was found that the addition of ligands generally decreased the fluorescence. This is possibly because the ligands cause the Quantum Dots to agglutinate, as shown in our TEM images. The ligands can form hydrogen bonds and dipole interactions with one another, resulting in the Quantum Dots clumping together. This reduces the surface area to volume ratio of the Quantum Dots and hence decreases the fluorescence efficiency. As ligand length increases, the effects of agglutination become more significant due to stronger dipole interactions and fluorescence decreases even more.

 

The effect of different functional groups of the ligand on the fluorescence of the samples could not be be concluded since ligands of different functional groups, when attached, resulted in different dominant wavelengths of fluorescence in the samples.