Conjugations between cysteamine-stabilized CdTe quantum dots and single stranded DNA

Cysteamine-stabilized CdTe quantum dots were used to directly conjugate with single stranded DNA through electrostatic attraction between positive amino function groups on the surface of CdTe quantum dots and negatively charged DNA. The conjugates exhibited different optical properties from that of CdTe quantum dots, for example, the fluorescence intensity was enhanced obviously with maximum emission peaks gradually red-shifting, and the conjugates were more stable. Under the optimum conditions, the fluorescence intensity was proportional to concentration of DNA over the range 0.16-0.48 mu g/mL. This proposed method demonstrated a versatile tool for the fluorescence probing of target DNA and fluorescence labeling.