Adaptation of inorganic quantum dots for stable molecular beacons

• Published in: Sensors and actuators. B, Chemical Vol. 102; no. 2; pp. 315 - 319
• Main Authors: Kim, Joong Hyun, Morikis, Dimitrios, Ozkan, Mihrimah
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 13.09.2004
• Subjects: DABCYL; Molecular beacon; Semiconductor quantum dot; Molecular beacon; DABCYL; Semiconductor quantum dot
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2004.04.107

We have developed semiconductor quantum dots (QDs)-conjugated molecular beacons (MBs). The organic fluorophores are replaced with inorganic fluorescent ZnS-capped CdSe quantum dots covered with mercaptoacetic acid monolayer. We confirmed the overlap between emission spectrum of the QD after the surface modification and the absorption spectrum of 4-(4′-dimethylaminophenylazo) benzoic acid (DABCYL) as an organic quencher molecule. About 90% overlap between QDs and DABCYLs’ spectra promotes fluorescent resonance energy transfer (FRET). FRET efficiency between QD-DABCYL and 6-FAM (organic fluorophore)-DABCYL are compared by using 3-D molecular modeling. The farthest and nearest possible separation between the fluorophore and the quencher are predicted using 3-D molecular model considering the rotational freedom of the bonds defined by the type of chemical linker between MB-fluorophore and MB-DABCYL. Finally, QD-modified MBs are tested with their complementary target deoxyribonucleic acid (DNA) sequence and for non-specific sequences. The use of QDs instead of organic fluorophores may offer multiplexed imaging during DNA or RNA analysis due to their broad UV absorption spectrum.