Compact,Polyvalent Mannose Quantum Dots as Sensitive,Ratiometric FRET Probes for Multivalent Protein–Ligand Interactions

A highly efficient cap‐exchange approach for preparing compact, dense polyvalent mannose‐capped quantum dots (QDs) has been developed. The resulting QDs have been successfully used to probe multivalent interactions of HIV/Ebola receptors DC‐SIGN and DC‐SIGNR (collectively termed as DC‐SIGN/R) using a sensitive, ratiometric Förster resonance energy transfer (FRET) assay. The QD probes specifically bind DC‐SIGN, but not its closely related receptor DC‐SIGNR, which is further confirmed by its specific blocking of DC‐SIGN engagement with the Ebola virus glycoprotein. Tuning the QD surface mannose valency reveals that DC‐SIGN binds more efficiently to densely packed mannosides. A FRET‐based thermodynamic study reveals that the binding is enthalpy‐driven. This work establishes QD FRET as a rapid, sensitive technique for probing structure and thermodynamics of multivalent protein–ligand interactions.     

Single‐Nanoparticle Cell Barcoding by Tunable FRET from Lanthanides to Quantum Dots

Fluorescence barcoding based on nanoparticles provides many advantages for multiparameter imaging. However, creating different concentration‐independent codes without mixing various nanoparticles and by using single‐wavelength excitation and emission for multiplexed cellular imaging is extremely challenging. Herein, we report the development of quantum dots (QDs) with two different SiO₂ shell thicknesses (6 and 12 nm) that are coated with two different lanthanide complexes (Tb and Eu). FRET from the Tb or Eu donors to the QD acceptors resulted in four distinct photoluminescence (PL) decays, which were encoded by simple time‐gated (TG) PL intensity detection in three individual temporal detection windows. The well‐defined single‐nanoparticle codes were used for live cell imaging and a one‐measurement distinction of four different cells in a single field of view. This single‐color barcoding strategy opens new opportunities for multiplexed labeling and tracking of cells.     

Positively Charged Compact Quantum Dot–DNA Complexes for Detection of Nucleic Acids

Selective DNA detection: The fluorescence, from stable cationic QDs, is quenched by 90% on complexation with modified DNA molecules. The QD–DNA probe is capable of detecting pathogenic DNA fragments at concentrations as low as 200 nM in solution and shows selective fluorescence recovery in the presence of target DNA (see spectrum c in figure) vs noncomplementary DNA (spectrum d).

     

Antimonene Quantum Dots: Synthesis and Application as Near‐Infrared Photothermal Agents for Effective Cancer Therapy

Photothermal therapy (PTT) has shown significant potential for cancer therapy. However, developing nanomaterials (NMs)‐based photothermal agents (PTAs) with satisfactory photothermal conversion efficacy (PTCE) and biocompatibility remains a key challenge. Herein, a new generation of PTAs based on two‐dimensional (2D) antimonene quantum dots (AMQDs) was developed by a novel liquid exfoliation method. Surface modification of AMQDs with polyethylene glycol (PEG) significantly enhanced both biocompatibility and stability in physiological medium. The PEG‐coated AMQDs showed a PTCE of 45.5 %, which is higher than many other NMs‐based PTAs such as graphene, Au, MoS₂, and black phosphorus (BP). The AMQDs‐based PTAs also exhibited a unique feature of NIR‐induced rapid degradability. Through both in vitro and in vivo studies, the PEG‐coated AMQDs demonstrated notable NIR‐induced tumor ablation ability. This work is expected to expand the utility of 2D antimonene (AM) to biomedical applications through the development of an entirely novel PTA platform.     

High‐Performance CsPb1−xSnxBr3 Perovskite Quantum Dots for Light‐Emitting Diodes

All inorganic CsPbBr₃ perovskite quantum dots (QDs) are potential emitters for electroluminescent displays. We have developed a facile hot‐injection method to partially replace the toxic Pb²⁺ with highly stable Sn⁴⁺. Meanwhile, the absolute photoluminescence quantum yield of CsPb_1−x Sn_x Br₃ increased from 45 % to 83 % with Sn^IV substitution. The transient absorption (TA) exciton dynamics in undoped CsPbBr₃ and CsPb_0.67Sn_0.33Br₃ QDs at various excitation fluences were determined by femtosecond transient absorption, time‐resolved photoluminescence, and single‐dot spectroscopy, providing clear evidence for the suppression of trion generation by Sn doping. These highly luminescent CsPb_0.67Sn_0.33Br₃ QDs emit at 517 nm. A device based on these QDs exhibited a luminance of 12 500 cd m⁻², a current efficiency of 11.63 cd A⁻¹, an external quantum efficiency of 4.13 %, a power efficiency of 6.76 lm w⁻¹, and a low turn‐on voltage of 3.6 V, which are the best values among reported tin‐based perovskite quantum‐dot LEDs.     

CdS Quantum Dots as Fluorescence Probes for the Detection of Selenite

Abstract

Water-soluble cadmium sulfide (CdS) quantum dots (QD) capped by mercaptoacetic acid were synthesized by aqueous-phase arrested precipitation and characterized by transmission electron microscopy, a spectrofluorometer, and an ultraviolet visible (UV-Vis) spectrophotometer. Based on the fluorescence quenching of CdS QD by selenite in the presence of glutathione (GSH), a simple, rapid, sensitive, and selective detection method for selenite was proposed. Under the optimum conditions, the calibration graph was linear in the range of 0.05 µmol L^?1 to 11.2 µmol L^?1. The limit of detection is 0.03 µmol L^?1. The usefulness of the proposed method was evaluated for the determination of selenite in sodium selenite tablet and sodium selenite and vitamin E injection, and the results agreed with the labeled values. In addition, the effect of foreign ions (common anions and biologically relevant cations) on the fluorescence of the CdS QD was examined to evaluate the selectivity. The quenching mechanism is also described.     

CdS Quantum Dots as Fluorescence Probes for Detection of Adriamycin Hydrochloride

IntroductionQuantum dots(QDs) have generated a great dealof interest because of their quantum confinement andsurface properties, which make possible the absorptionand emission of size-tuned QDs, thereby resulting inlarge Stokes shifts[1,2]. Because of the…     

Photo‐Cross‐Linked Small‐Molecule Microarrays as Chemical Genomic Tools for Dissecting Protein–Ligand Interactions

We have developed a unique photo‐cross‐linking approach for immobilizing a variety of small molecules in a functional‐group‐independent manner. Our approach depends on the reactivity of the carbene species generated from trifluoromethylaryldiazirine upon UV irradiation. It was demonstrated in model experiments that the photogenerated carbenes were able to react with every small molecule tested, and they produced multiple conjugates in most cases. It was also found in on‐array immobilization experiments that various small molecules were immobilized, and the immobilized small molecules retained their ability to interact with their binding proteins. With this approach, photo‐cross‐linked microarrays of about 2000 natural products and drugs were constructed. This photo‐cross‐linked microarray format was found to be useful not merely for ligand screening but also to study the structure–activity relationship, that is, the relationship between the structural motif (or pharmacophore) found in small molecules and its binding affinity toward a protein, by taking advantage of the nonselective nature of the photo‐cross‐linking process.