Minimizing the fluorescence quenching caused by uncontrolled aggregation of CdSe/CdS core/shell quantum dots for biosensor applications

The fluorescence quenching of CdSe/CdS core/shell quantum dots (QDs) with various shell thicknesses is investigated. Inducing aggregation of the core/shell QDs with the addition of NaCl shows that the fluorescence quenching efficiency decreases monotonically as the CdS shell thickness increases because of the reduced spectral overlap between the emission and absorption spectra. In addition, hybridization between the oligonucleotide-functionalized QDs and its complementary DNA with the fluorescent dye is used to study the fluorescence quenching caused by the Förster resonance energy transfer (FRET) and any uncontrolled aggregation. These experiments allow quantitative estimation of the effects of FRET and uncontrolled aggregation on the fluorescence quenching efficiency, which can be used to determine conditions to minimize undesirable fluorescence quenching due to uncontrolled aggregation in energy transfer-based biosensor applications.