Near‐Infrared SERS Nanoprobes with Plasmonic Au/Ag Hollow‐Shell Assemblies for In Vivo Multiplex Detection

For the effective application of surface‐enhanced Raman scattering (SERS) nanoprobes for in vivo targeting, the tissue transparency of the probe signals should be as high as it can be in order to increase detection sensitivity and signal reproducibility. Here, near‐infrared (NIR)‐sensitive SERS nanoprobes (NIR SERS dots) are demonstrated for in vivo multiplex detection. The NIR SERS dots consist of plasmonic Au/Ag hollow‐shell (HS) assemblies on the surface of silica nanospheres and simple aromatic Raman labels. The diameter of the HS interior is adjusted from 3 to 11 nm by varying the amount of Au³⁺ added, which results in a red‐shift of the plasmonic extinction of the Au/Ag nanoparticles toward the NIR (700–900 nm). The red‐shifted plasmonic extinction of NIR SERS dots causes enhanced SERS signals in the NIR optical window where endogenous tissue absorption coefficients are more than two orders of magnitude lower than those for ultraviolet and visible light. The signals from NIR SERS dots are detectable from 8‐mm deep in animal tissues. Three kinds of NIR SERS dots, which are injected into live animal tissues, produce strong SERS signals from deep tissues without spectral overlap, demonstrating their potential for in vivo multiplex detection of specific target molecules.     

Efficient Near‐Infrared Light‐Emitting Diodes based on In(Zn)As–In(Zn)P–GaP–ZnS Quantum Dots

Near‐infrared (NIR) lighting plays an increasingly important role in new facial recognition technologies and eye‐tracking devices, where covert and nonvisible illumination is needed. In particular, mobile or wearable gadgets that employ these technologies require electronic lighting components with ultrathin and flexible form factors that are currently unfulfilled by conventional GaAs‐based diodes. Colloidal quantum dots (QDs) and emerging perovskite light‐emitting diodes (LEDs) may fill this gap, but generally employ restricted heavy metals such as cadmium or lead. Here, a new NIR‐emitting diode based on heavy‐metal‐free In(Zn)As–In(Zn)P–GaP–ZnS quantum dots is reported. The quantum dots are prepared with a giant shell structure, enabled by a continuous injection synthesis approach, and display intense photoluminescence at 850 nm with a high quantum efficiency of 75%. A postsynthetic ligand exchange to a shorter‐chain 1‐mercapto‐6‐hexanol (MCH) affords the QDs with processability in polar solvents as well as an enhanced charge‐transport performance in electronic devices. Using solution‐processing methods, an ITO/ZnO/PEIE/QD/Poly‐TPD/MoO₃/Al electroluminescent device is fabricated and a high external quantum efficiency of 4.6% and a maximum radiance of 8.2 W sr^?1 m^?2 are achieved. This represents a significant leap in performance for NIR devices employing a colloidal III–V semiconductor QD system, and may find significant applications in emerging consumer electronic products.     

Cover Picture: Encapsulation of Water‐Immiscible Solvents in Polyglutamate/ Polyelectrolyte Nanocontainers (Adv. Funct. Mater. 8/2007)

A novel approach for encapsulation of hydrophobic materials into hydrophilic multifunctional shells is based on combining ultrasonic techniques and layer‐by‐layer protocols. Polyglutamate/polyelectrolyte nanocontainers of 600 nm size loaded with hydrophobic tetraphenylporphin are fabricated in work reported by Dmitri Shchukin and co‐workers on p. 1273. The hydrophobic core of the nanocontainers can encapsulate a huge variety of water‐insoluble drugs and the outer hydrophilic polyelectrolyte shell has controlled permeability and multifunctionality. A novel approach for encapsulation of hydrophobic materials into a hydrophilic multifunctional shell is presented, based on combining an ultrasonic technique and a layer‐by‐layer protocol. Polyglutamate/polyethyleneimine (PEI)/polyacrylic acid (PAA) and polyglutamate/PEI/PAA/silver nanocontainers loaded with a hydrophobic dye, 5,10,15,20‐tetraphenylporphin, dissolved in toluene, are fabricated. Uniform, stable, and monodisperse polyglutamate/PEI/PAA nanocontainers of about 600 nm are obtained. The hydrophobic core of the nanocontainers might contain a huge variety of water‐insoluble drugs and the outer polyelectrolyte shell may provide controlled permeability and desired multifunctionality. Confocal fluorescence microscopy and scanning electron microscopy are employed for the characterization of the resulting nanocontainers. Using sodium dodecyl sulfate as surfactant, the amount of nanocontainers, their monodispersity, and stability can be increased dramatically.