Quantum dot

The residue of doxycycline in food can cause harm to human. Therefore, the detection of doxycycline residue is necessary. Herein, a ratiometric fluorescent probe was designed based on sulfur quantum dots (S dots) and Ca2+ . Due to static quenching and inter filter effect between doxycycline and S dots, doxycycline quenched fluorescence of S dots at 450 nm. Meanwhile, doxycycline and Ca2+ formed fluorescent complex through coordination to produce new peak at 520 nm. The ratio of fluorescence intensity (F520 /F450 ) and doxycycline concentration showed good linear relationship with detection limit of 0...

This review traces nanocrystal quantum dot (QD) research from the early discoveries to the present day and into the future. We describe the extensive body of theoretical and experimental knowledge that comprises the modern science of QDs. Indeed, the spatial confinement of electrons, holes, and excitons in nanocrystals, coupled with the ability of modern chemical synthesis to make complex designed structures, is today enabling multiple applications of QD size-tunable electronic and optical properties.

Light-emitting chiral carbonized polymer dots (Ch-CPDs) are attracting great interest due to their extraordinary photonic properties, but modulating their bandgap emission, especially at long wavelength, and maintaining their chiral structure to achieve multi-color, high-emission Ch-CPDs remains challenging. Here we report for the first time the synthesis of red- and multi-color emitting Ch-CPDs using the common precursors L-/D-tryptophan and o-phenylenediamine and a solvothermal approach at one temperature...

During the last decades, there has been growing interest in using therapeutic messager RNA (mRNA) together with drug delivery systems. Naked, unformulated mRNA is, however, unable to cross the cell membrane and is susceptible to degradation. Here we use graphene quantum dots (GQDs) functionalized with polyethyleneimine (PEI) as a novel mRNA delivery system. Our results show that these modified GQDs can be used to deliver intact and functional mRNA to Huh-7 hepatocarcinoma cells at low doses and, that the GQDs are not toxic, although cellular toxicity is a problem for these first-generation modified particles...

Salinity has destructive impacts in plant production; therefore, application of new approaches such as nanotechnology and plant priming is attracting increasing attention as an innovative means to ameliorate salt stress effects. Considering the unique properties and recorded beneficial influence of carbon quantum dots (CQDs) and proline in plant growth and physiological parameters when applied individually, their conjugation in the form of carbon quantum dot nanoparticles functionalized by proline (Pro-CQDs NPs) could lead to synergistic effects...

Carbon quantum dots (CDs), as one of the most potential fluorescent sensing materials, have attracted lots of attention in recent years. However, the low quantum yields (QYs), complicated separation and purification procedures have limited its application and large-scale production. In this paper, a facile and universal method was successfully developed to synthesize CDs-silica (SiO2) spheres composites (CS composites), which not only demonstrates 10-fold fluorescence enhancement compared with single CDs but also enables the purification with a simple centrifugation step...

The scrambling rate λs a measure of the early growth of decoherence in an interacting quantum system, has been conjectured to have a universal saturation bound, λs ≤ 2πkΒ T/ℏ, where T is the temperature. This decoherence arises from the spread of quantum information over a large number of untracked degrees of freedom. The commonly studied indicator of scrambling is the out of time-ordered correlator (OTOC) of noncommuting quantum operators, in-turn related to generalized uncertainty relations, and reminiscent of the Lyapunov exponent of classically chaotic systems...

As a potential carcinogen produced in food thermal processing, acrylamide (AM) can cause irreversible harm to human health. For the detection of AM in food products, a simple fluorescent biosensor based on single-stranded DNA (ssDNA) and carbon quantum dots (CQDs) was developed. Reduced fluorescence intensity of CQDs at 445 nm (excitation at 350 nm) was induced by the attachment of ssDNA. In the presence of AM, ssDNA was preferentially bound to AM by hydrogen bonding and the degree of fluorescence reduction was smaller than that without AM...

Quantum entanglement has been realized on a variety of physical platforms such as quantum dots, trapped atomic ions, and superconductors. Here we introduce specific molecular solids as promising alternative platforms. Our model system is triplet pentacene in a host single crystal at level anticrossing (LAC) conditions. First, a laser pulse generates the triplet state and initiates entanglement between an electron spin and 14 hyperfine coupled proton spins (quantum bits or qubits). This gives rise to large nuclear spin polarization...

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No abstract text is available yet for this article.

A MnO2 nanosheet-assisted ratiometric fluorescence probe based on carbon quantum dots (CQDs) and o-phenylenediamine (OPD) has been developed for the detection of the anticancer drug 6-mercaptopurine (6-MP). CQDs with strong fluorescence are synthesized via the one-step hydrothermal method. MnO2 nanosheets as an oxidase-mimicking nanomaterial directly oxidize OPD into 2,3-diaminophenazine (DAP) which has a fluorescence emission at 570 nm, whereas the fluorescence of CQDs at 445 nm is then reduced by the DAP through the inner filter effect (IFE) under a single excitation wavelength (370 nm)...

A cost-effective, facile, and sensitive fluorescence sensing strategy for Pb2+ ion detection has been developed based on the fluorescence resonance energy transfer (FRET) between carbon quantum dots (CQDs) and Au nanoparticles (NPs). Glutathione (GSH)-synthesized CQDs acted as both the fluorescence donor and the sorbent to extract Pb2+ ions from the solution via Pb-GSH complexes. Pb2+ ions on CQDs reacted with -SH groups on AuNPs to generate sandwich-type Au-PdS-CQDs, leading to a dramatic decrease in the fluorescence of the CQDs...

Purpose: Sensitive and selective point-of-care biosensor is an urgent pursuit of serological antibody detection to control parasite pathogen. For specific, quantitative and on-site screening of Trichinella spiralis infection in livestock, a quantum dot nanobead-monoclonal antibody (QB-mAb) probe-based immunochromatographic assay (ICA) was developed by introducing a competitive sandwich strategy (QB-CICA). Methods: In the QB-CICA, QB-mAb probes competed with serum antibody for a particular epitope, followed by immunocomplexes binding to capture antibody on the test line...

Interfacial solar evaporation (ISE) is an environmentally friendly and promising water treatment strategy. However, the bactericidal performance of an ISE system during the evaporation process is usually ignored, which may result in potential water safety hazards. In this study, a facile method is presented for the controllable synthesis of Ag quantum dots (QDs)/rGO to simultaneously achieve efficient solar evaporation and evaporated water disinfection. The size of the Ag nanoparticles (NPs) rather than the loading amount is the factor that considerably affects the solar evaporation efficiency and the bactericidal performance...

Functional separators, which are chemically modified and coated with nanostructured materials, are considered an effective and economical approach to suppressing the shuttle effect of lithium polysulfide (LiPS) and promoting the conversion kinetics of sulfur cathodes. Herein, we report cobalt-aluminum-layered double hydroxide quantum dots (LDH-QDs) deposited with nitrogen-doped graphene (NG) as a bifunctional separator for lithium-sulfur batteries (LSBs). The mesoporous LDH-QDs/NG hybrids possess abundant active sites of Co2+ and hydroxide groups, which result in capturing LiPSs through strong chemical interactions and accelerating the redox kinetics of the conversion reaction, as confirmed through X-ray photoelectron spectroscopy, adsorption tests, Li2 S nucleation tests, and electrokinetic analyses of the LiPS conversion...

To utilize the nanomaterials as an effective carrier for the drug delivery applications, it is important to study the interaction between nanomaterials and drug or biomolecules. In this study GSH functionalized Mn2+ -doped CdTe/ZnS QDs has been utilized as a model nanomaterial due to its high luminescence property. Folic acid (FA) gradually quenches the FL of GSH functionalized Mn2+  - doped CdTe/ZnS QDs. The Stern-Volmer quenching constant (Ksv ), binding constant (Ks ) and effective quenching constant (Ka) for the FA-QDs system is calculated to be 1...

Regulating nonlinear optical (NLO) absorption and refraction properties of graphene is significant in nonlinear photonics. In this work, the functionalizing strategy of quantum dots (QDs) was used for the regulation of the NLO properties of reduced graphene oxide (rGO) with Au nanospheres and Au@CdS core-shells. The third-order NLO properties of rGO-Au and rGO-Au@CdS nanocomposites were investigated by Z-scan technique with 38 ps laser pulses at 532 nm wavelength. The saturation absorption (SA) of rGO was weakened when it was combined with Au nanospheres and switched to reverse saturation absorption (RSA) when combined with Au@CdS core-shells as irradiance intensity increased...

Arrays of quantum dot micropillar lasers are an attractive technology platform for various applications in the wider field of nanophotonics. Of particular interest is the potential efficiency enhancement as a consequence of cavity quantum electrodynamics effects, which makes them prime candidates for next generation photonic neurons in neural network hardware. However, particularly for optical pumping, their power-conversion efficiency can be very low. Here we perform an in-depth experimental analysis of quantum dot microlasers and investigate their input-output relationship over a wide range of optical pumping conditions...

Auger recombination is an ultrafast and unnegligible photophysical process in colloidal semiconductor quantum dots (QDs) due to competition with charge separation or radiative recombination processes, pivotal for their applications ranging from bio-labeling, light-emitting diodes, QD lasing to solar energy conversion. Among diverse QDs, ternary chalcopyrite is recently receiving significant attention for its heavy-metal free property and remarkable optical performance. Given deficient understanding of the Auger process for ternary chalcopyrite QDs, CuInS2 QDs with various sizes are synthesized as a representative and the bi-exciton lifetime (τBX ) is derived by virtue of ultrafast time resolved absorption spectrum...