Optical detection of gadolinium(iii) ions via quantum dot aggregation

Abstract

CdTe quantum dot aggregation induced by trivalent metal ions is followed using fluorescence, dynamic light scattering and fluorescence correlation spectroscopy.

"Off/On” Fluorescent Probe based on Aggregation-Induced Quenching of ZnO-Quantum dots for Determination of Ara-C: Pharmacokinetic Applications, Adsorption Kinetics & Green Profile Assessment

“…Figure 1 b shows the formation of large disordered ZnO-QDs aggregates without morphological change when Ce 4+ ions were added which may be attributed to the ground-state electronic coupling or energy transfer through aggregates [ 38 ].…”

A guide to small fluorescent probes for single-molecule biophysics

“…We note that the extinction coefficients at the first exciton peak are much lower than those at shorter wavelengths, in contrast to organic dyes which have their largest extinction coefficient at the peak of their absorption spectrum. Coupled with their broad excitation spectra which increase towards the UV, relatively long lifetimes ( > 10 ns) and resistance to chemical degradation, CdTe and CdSe QDs are excellent candidates for tracking time-dependent dynamic processes (154) , biomedical imaging including in vivo tumour detection (167,168) , deep tissue imaging (169) , environmental sensing (170,171) and antibody detection (172) .…”

“…While the root cause of photoblinking is still debated, evidence points towards a mechanism in which electron transfer to trap states in the QD or surrounding matrix leads to photoinduced charging (198,199) . QD photoblinking provides a simple way of achieving super-resolution localization via conventional fluorescence microscopy (200) and blinking rates may be modulated in the presence of ions, offering environmental sensitivity (170,201,202) . Taken together, understanding, suppressing and manipulating the blinking characteristics of QDs are important lines of single-particle research.…”

An approach toward miRNA detectionviadifferent thermo-responsive aggregation/disaggregation of CdTe quantum dots

“…But aer addition of miR-155 and duplex formation with DNA probe, the interaction between chalcogenide QDs and DNA/miRNA heteroduplex [21][22][23][24][25][26][27] results in aggregation of the QD nanoparticles and their UV-vis absorption coefficient is reduced and therefore, their uorescence intensity also is reduced ("signal off") [28][29][30][31][32] (Scheme 3a 0 ). Then, by applying melting temperature, DNA probe strand dissociated from miRNA and red emission (at 615 nm) can be observed ("signal on") [32][33][34][35][36] (Scheme 3b 0 ). This is due to the shorter distances between the CdTe QDs in the dsDNA/miRNA than that of the ssDNA and free CdTe QDs, which can increase the dipole-dipole interaction between the CdTe QDs resulting in a larger Stoke's shi emission change.…”

“…Here, this nucleic acid heteroduplex aggregates thioglycolic acid (TGA)-stabilized CdTe QDs; and as a result, uorescence quenching occurs. [28][29][30][31][32] Applying melting temperature (T m : is dened as the temperature at which half of the double strand begins to dissociate), resulted in a larger Stoke's shi emission change upon the de-aggregation, [32][33][34][35][36] which depends on the concentration of miRNA. This is due to the shorter distances between the CdTe QDs in the heteroduplex than that of the single strand and free CdTe QDs, which can increase the dipole-dipole interaction between the CdTe QDs, resulting in a larger Stoke's shi emission change (Schemes 1-3).…”