Phosphine-Free, Highly Emissive, Water-Soluble Mn:ZnSe/ZnS Core–Shell Nanorods: Synthesis, Characterization, and in Vitro Bioimaging of HEK293 and HeLa Cells

Abstract

Phosphine-free, highly luminescent one-dimensional Mn2+ ion-doped ZnSe­(core)/ZnS­(shell) nanorods (NRs) were synthesized by heating-up method (core) followed by hot injection route (shell). Effect of Mn2+ doping and shell thickness on structural and optical properties is reported. The NRs were formed with wurtzite-structured Mn:ZnSe core (diameter 2.52 nm) encapsulated epitaxially by a wurtzite-structured ZnS shell (thickness of 3.51 nm) with 3.1% lattice mismatch that alters the band alignment of the overall core–shell structure. A redshift was observed in optical absorption and photoluminescence (PL) emission due to an overall size increase with increasing shell thickness. Because of the reduction of defects/traps by surface passivation, the maximum photoluminescence quantum yield (QY) was obtained to be 49.35%. The exciton radiative lifetime for the core–shell NRs (1.678 ms) was more prolonged than that of the core (0.573 ms). A clear dependence of QY and lifetime was established on the Mn2+ content and ZnS shell thickness. The core–shell structure with thickest shell showed good photostability. Water solubility was achieved by ligand exchange with bifunctional 11-mercaptoundecanoic acid without modifying the optical and microstructural properties. These core–shell NRs were successfully tested for bioimaging of human HEK293 and HeLa cells with good permeability to cells. Toxicity was observed to be 3% for the 100 μg/mL dose.

Colloidal Gradated Alloyed (Cu)ZnInS/ZnS Core/Shell Nanocrystals with Tunable Optical Properties for Live Cell Optical Imaging

“…The degree of hypsochromic shift is increased from 13 to 51 nm with increasing Cu molar concentration in the core QDS (Table ). This hypsochromic shift of PL emission remarkably differs from the general bathochromic shift observed in emission for the binary systems after coating with ZnS shell ,. A similar result (hypsochromic shift in emission) was also observed in the previously reported ternary/quaternary alloy based core/shell systems ,,,,.…”

Nonepitaxial Gold‐Tipped ZnSe Hybrid Nanorods for Efficient Photocatalytic Hydrogen Production

“…As for S 2p, it has closely spaced spin–orbit components ( Δ = 1.16 eV, intensity ratio = 0.511) which overlap with those of Se 3p. The XPS spectrum of ZnSe NRs synthesized using dodecanethiol and oleylamine as the surfactant/solvents in this work was dominated by two peaks at 160.3 and 166.0 eV, which can be assigned to Se 3p 3/2 and Se 3p 5/2 , respectively . The other two weak peaks positioned at 162.4 and 163.5 eV correspond to the typical value of metal–thiol binding energy of S 2p …”

“…First, ZnSe NRs were synthesized by a heat‐up method according to a previously reported method with some modifications (see the Experimental Section in the Supporting Information). In a typical synthesis, zinc acetate and selenium powder were employed as the precursors while oleylamine (OLA) and 1‐dodecanethiol (DDT) were used as the ligand and solvent, respectively, to synthesize ZnSe NRs at 260 °C using standard Schleck techniques.…”

A Tunneling Dielectric Layer Free Floating Gate Nonvolatile Memory Employing Type‐I Core–Shell Quantum Dots as Discrete Charge‐Trapping/Tunneling Centers

“…Besides, considering the optoelectronic versatility of semiconductors compared with metals, it is worth investigating the application of semiconductor nanoparticles with the same charge confinement ability as the metal‐dielectric structure (e.g., type‐I core–shell quantum dots) in the FGT. In the present work, we demonstrate that the type‐I ZnSe/ZnS core–shell quantum dots, which do not contain toxic or noble element, can operate well as the discrete charge‐trapping/tunneling centers in an FGT nonvolatile memory. This FGT nonvolatile memory based on ZnSe/ZnS core–shell quantum dots showed a large memory window, a good endurance, and a stable retention.…”

“…The ZnSe@ZnS‐OA QDs solution in toluene was synthesized by capping three monolayers of ZnS on the ZnSe‐OA QDs using a so‐called “successive ion layer adsorption and reaction” method . The ZnSe‐MPA and ZnSe@ZnS‐MPA QDs solutions in deionized water (DI water) were obtained separately by replacing the surface ligand of ZnSe‐OA and ZnSe@ZnS‐OA QDs with mercaptopropionic acid using a reported procedure . The concentrations of these four solutions were roughly adjusted to be about 10 mg mL −1 .…”