Optimized linkage and quenching strategies for quantum dot molecular beacons

Preparation of fluorescent DNA probe by solid-phase organic synthesis

“…The residual free QDs would increase the background fluorescence of probe based on inorganic nanoparticles, and the residual unreacted ssDNA would hybridize with the complementary ssDNA in the system. In this work, the amount of QDs and ssDNA were nearly equal, and only simple filtration could remove the free ssDNA and nanoparticles because of the huge difference of particle sizes between solid-phase carriers and ssDNA rather than the slight difference of particle size or solubility between residual free nanoparticles and ssDNA conjugated nanoparticles in traditional ways [11][12][13]15]. When the pH was about 10, the Au-DNA and QD-DNA were cut off from the carriers.…”

“…CdTe QDs and AuNPs are a suitable donor-acceptor pair [13] because the emission spectrum of CdTe QDs and the absorption spectrum of AuNPs have a large overlap [15]. After hybridization between CdTe-DNA and Au-DNA, the CdTe and Au nanoparticles were close, therefore the fluorescence intensity of donors would decrease because of the energy transfer from the donors to acceptors and the formation of fluorescence probes with inorganic nanoparticles conjugated double-stranded DNA (QD-dsDNA-Au probe) [14,15].…”

“…As novel luminescent inorganic fluorophores, Quantum dots (QDs) are currently being widely used in biological probes, in vitro assay detection, in vivo cell labeling and imaging, because QDs show a broad and continuous excitation spectrum, narrow size-tunable symmetric emission spectrum and high fluorescence quantum yield [3][4][5][6][7][8]. Recently, complex nanostructures formed by linking QDs as energy donors and gold nanoparticles (AuNPs) as energy acceptors through DNA hybridization or streptavidin-biotin interaction have also been realized [9][10][11][12][13] and applied in the sensing biomolecular concentration [10]. AuNPs have a high extinction coefficient and a broad absorption spectrum in visible light that is overlapped by the emission wavelength of the usual energy donors.…”

“…In reported works, the amount of nanoparticles (QDs or AuNPs) exceeded that of DNA [11,15], thus less unreacted DNA would exist in system and the separation and purification of ssDNA conjugated AuNPs (Au-DNA) and QDs (QD-DNA) from reaction system could be mainly focused on the utilization of the differences between free nanoparticles and ssDNA conjugated nanoparticles. In traditional way, nanoparticles which were not linked to DNA were not subject to purification processes [12,15] or removed by ethanol precipitation [11] or spin filtration [13], and so on. Free ssDNA and nanoparticles which remained in system would influence the precision of detection and repetition ability of DNA probe.…”

Polymer-functionalized Gold Nanoparticles as Versatile Sensing Materials

“…82 The introduction of a gold nanoparticle enhanced the sensitivity up to 100-fold and improved the detectability for a single mismatch eight-fold compared to conventional MBs. 83 …”