Semiconductor quantum dots (QDs) could significantly impact the performance of biomedical near-infrared (NIR) imaging by providing fluorescent probes that are brighter and more photostable than conventional organic dyes. However, toxicity components NIR emitting II-VI IV-VI QDs have been made so far (Cd, Hg, Te, Pb, etc.) has remained a major obstacle to clinical use QDs. Here, we present synthesis CuInS(2)/ZnS core/shell in ( approximately 800 nm) with good yield stability even after...

We have designed and synthesized a series of modular ligands based on poly(ethylene glycol) (PEG) coupled with functional terminal groups to promote water-solubility biocompatibility quantum dots (QDs). Each ligand is comprised three modules: PEG single chain hydrophilicity, dihydrolipoic acid (DHLA) unit connected one end the for strong anchoring onto QD surface, potential biological group (biotin, carboxyl, amine) at other PEG. Water-soluble QDs capped these were prepared via cap exchange...

Luminescent quantum dots (QDs) were proven to be very effective fluorescence resonance energy transfer donors with an array of organic dye acceptors, and several based biosensing assemblies utilizing QDs have been demonstrated in the past few years. Conversely, gold nanoparticles (Au-NPs) are known for their capacity induce strong quenching conventional donors. Using a rigid variable-length polypeptide as bifunctional biological linker, we monitor photoluminescence CdSe-ZnS by Au-NP...

Luminescent semiconductor nanocrystals or quantum dots (QDs) are a recentlydeveloped class of nanomaterial whose unique photophysical properties helping tocreate new generation robust fluorescent biosensors. QD interest forbiosensing include high yields, broad absorption spectra coupled to narrow sizetunablephotoluminescent emissions and exceptional resistance both photobleaching andchemical degradation. In this review, we examine the progress in adapting QDs for severalpredominantly vitro...

To investigate the effect of branching on linear and nonlinear optical properties, a specific series chromophores, epitome (multi)branched dipoles, has been thoroughly explored by combined theoretical experimental approach. Excited-state structure calculations based quantum-chemical techniques (time-dependent density functional theory) as well Frenkel exciton model nicely complement photoluminescence one- two-photon absorption findings contribute to their interpretation. This allowed us get...

Luminescent semiconductor quantum dots (QDs) have great potential for use in biological assays and imaging. These nanocrystals are capped with surface ligands (bifunctional molecules, amphiphilic polymers, phospholipids, etc.) that render them hydrophilic provide functional properties. coatings alters their hydrodynamic radii charge, which can drastically affect properties such as diffusion within the cell cytoplasm. Heavy atom techniques transmission electron microscopy X-ray scattering...

We present a single particle fluorescence resonance energy transfer (spFRET) study of freely diffusing self-assembled quantum dot (QD) bioconjugate sensors, composed CdSe-ZnS core-shell QD donors surrounded by dye-labeled protein acceptors. first show that there is direct correlation between and ensemble FRET measurements in terms derived efficiencies donor-acceptor separation distances. also find that, addition to increased sensitivity, spFRET provides information about efficiency...

We present a molecular characterization of metal-affinity driven self-assembly between CdSe−ZnS core−shell quantum dots (QDs) and series proteins peptides appended with various length polyhistidine tags. In particular, we investigated the kinetics surface-immobilized QDs proteins/peptides under flow conditions, as well freely diffusing (solution phase). first configuration, were immobilized onto functionalized substrates then exposed to dye-labeled peptides/proteins. Using evanescent wave...

We demonstrate the use of self-assembled luminescent semiconductor quantum dot (QD)−peptide bioconjugates for selective intracellular labeling several eukaryotic cell lines. A bifunctional oligoarginine penetrating peptide (based on HIV-1 Tat protein motif) bearing a terminal polyhistidine tract was synthesized and used to facilitate transmembrane delivery QD bioconjugates. The sequence allows self-assemble onto surface via metal-affinity interactions while specific across cellular membrane...

[structure: see text] Novel octupolar fluorophores derived from the symmetrical functionalization of a triphenylamine core with strong acceptor peripheral groups via phenylene-ethynylene linkers have been synthesized and shown to exhibit high fluorescence quantum yields, very large TPA cross-sections in red-NIR region, suitable photostability.

We have developed a novel surface coating for semiconductor quantum dots (QDs) based on heterobifunctional ligand that overcomes most of the previous limits these fluorescent probes in bioimaging applications. Here we show QDs capped with bidentate zwitterionic dihydrolipoic acid−sulfobetaine (DHLA−SB) ligands are favorable alternative to polyethylene glycol-coated nanoparticles since they combine small sizes, low nonspecific adsorption, preserved optical properties, and excellent stability...

Self-assembly of proteins, peptides, DNA, and other biomolecules to semiconductor quantum dots (QD) is an attractive bioconjugation route that can circumvent many the problems associated with covalent chemistry subsequent purification. Polyhistidine sequences have been shown facilitate self-assembly proteins peptides ZnS-overcoated CdSe QDs via complexation unoccupied coordination metal sites on nanocrystal surface. We describe synthesis characterization a thiol-reactive hexahistidine...

Near-infrared (NIR) semiconductor quantum dots (QDs) represent promising fluorescent probes for biological and biomedical imaging. CuInSe2 is a good candidate these applications due to its bandgap in the near-infrared reduced toxicity of components compared other NIR QD materials (CdTe, CdHgTe, PbS, etc.). Here we present simple one-pot synthetic route without injection make sphalerite Cu−In−Se core Cu−In−Se/ZnS core/shell QDs. We show that photoluminescence (PL) resulting QDs can be tuned...

We utilize cell penetrating peptide functionalized QDs as specific vectors for the intracellular delivery of model fluorescent protein cargos. Multiple copies two structurally diverse proteins, 27 kDa monomeric yellow and 240 multichromophore b-phycoerythrin complex, were attached to using either metal-affinity driven self-assembly or biotin−Streptavidin binding, respectively. Cellular uptake these complexes was found depend on additional presence cell-penetrating peptides within QD−protein...

Biocompatible, near‐infrared luminescent gold nanoclusters (AuNCs) are synthesized directly in water using poly(ethylene glycol)‐dithiolane ligands terminating either a carboxyl, amine, azide, or methoxy group. The ≈1.5 nm diameter AuNCs fluoresce at ≈820 with quantum yields that range from 4–8%, depending on the terminal functional group present, and display average luminescence lifetimes approaching 1.5 μs. two‐photon absorption (TPA) cross‐section excited fluorescence (TPEF) properties...

We report the synthesis and properties of a novel class nanocrystals with mixed dimensionality: dot-in-plate core/shell nanostructure. This system was synthesized by growing flat, disk-shaped, CdS shell on spherical CdSe cores. The anisotropic pressure induced drastically splits first exciton fine structure in two: “heavy hole” “light states become separated up to 65 meV. As result, these exhibit an emission strongly polarized two dimensions, plane perpendicular wurtzite crystal c axis. use...

Colloidal quantum dots (QDs) have a large fraction of their atoms arrayed on surfaces and are capped with bifunctional ligands, which make photoluminescence highly sensitive to potential charge transfer or from the surrounding environment. In this report, we used peptides as bridges between CdSe-ZnS QDs metal complexes promote QDs. We found that quenching QD emission is dependent relative position oxidation levels complex used; it also traces number brought in close proximity nanocrystal...

We have designed new nanoprobes applicable for both positron emission tomography (PET) and optical fluorescence in vivo imaging. Fluorine-18, which is commonly used clinical imaging, has been coupled to phospholipid quantum dot (QD) micelles. This probe was injected mice we demonstrated that its dynamic quantitative whole body biodistribution pharmacokinetics could be monitored using PET as well the kinetics of their cellular uptake fibered confocal Phospholipid micelle encapsulation QDs...

Nonradiative fluorescence resonance energy transfer (FRET) between a luminescent quantum dot (QD) donor and proximal dye brought in close proximity of the QD surface via conjugation with dye-labeled peptide (or protein) is shown (see figure). The system excited near IR irradiation (well below absorption band QD), fast two-photon process, which produces FRET signal very low background contribution due to substantially reduced nonlinear direct excitation dye. Supporting information for this...

We characterized the resonance energy transfer interactions for conjugates consisting of QD donors self-assembled with three distinct fluorescent protein acceptors: two monomeric proteins, dsRed derivative mCherry or yellow and multi-chromophore b-phycoerythrin light harvesting complex. Using steady-state time-resolved fluorescence, we showed that nonradiative excitation in these can be described within Förster dipole-dipole formalism, efficiencies vary degree spectral overlap,...