Near-infrared two-photon excited photoluminescence from Yb-doped CsPbClBr perovskite nanocrystals embedded into amphiphilic silica microspheres.

Nonlinear absorption of metal-halide perovskite nanocrystals (NCs) makes them an ideal candidate for applications which require multiphoton-excited photoluminescence. By doping perovskite NCs with lanthanides, their emission can be extended into the near-infrared (NIR) spectral region. We demonstrate how the combination of Yb doping and bandgap engineering of cesium lead halide perovskite NCs performed by anion exchange (from Cl to Br) leads to efficient and tunable emitters that operate under two-photon excitation in the NIR spectral region.

One-Pot Synthesis of Silica-Coated Gold Nanostructures Loaded with Cyanine 5.5 for Cell Imaging by SERS Spectroscopy.

Anisotropic gold nanoparticles have been recognized as promising agents for medical diagnostics and cancer therapy due to their wide functionality, photothermal effect, and ability for optical signal amplification in the near-infrared range. In this work, a simple and rapid method for the preparation of bone-shaped gold nanoparticles coated with a dye-impregnated silica shell with an aminated surface is proposed. The possibility of further functionalization the nanostructures with a delivery vector using folic acid as an example is demonstrated.

Carbon Dot Emission Enhancement in Covalent Complexes with Plasmonic Metal Nanoparticles.

Carbon dots can be used for the fabrication of colloidal multi-purpose complexes for sensing and bio-visualization due to their easy and scalable synthesis, control of their spectral responses over a wide spectral range, and possibility of surface functionalization to meet the application task. Here, we developed a chemical protocol of colloidal complex formation via covalent bonding between carbon dots and plasmonic metal nanoparticles in order to influence and improve their fluorescence. We demonstrate how interactions between carbon dots and metal nanoparticles in the formed complexes, and thus their optical responses, depend on the type of bonds between particles, the architecture of the complexes, and the degree of overlapping of absorption and emission of carbon dots with the plasmon resonance of metals.

Near-Infrared Emission of HgTe Nanoplatelets Tuned by Pb-Doping.

Doping the semiconductor nanocrystals is one of the most effective ways to obtain unique materials suitable for high-performance next-generation optoelectronic devices. In this study, we demonstrate a novel nanomaterial for the near-infrared spectral region. To do this, we developed a partial cation exchange reaction on the HgTe nanoplatelets, substituting Hg cations with Pb cations.

Engineering the Optical Properties of CsPbBr Nanoplatelets through Cd Doping.

Lead halide perovskite nanoplatelets (NPls) attract significant attention due to their exceptional and tunable optical properties. Doping is a versatile strategy for modifying and improving the optical properties of colloidal nanostructures. However, the protocols for B-site doping have been rarely reported for 2D perovskite NPls.

Dual-Purpose Sensing Nanoprobe Based on Carbon Dots from o-Phenylenediamine: pH and Solvent Polarity Measurement.

Today, the development of nanomaterials with sensing properties attracts much scientific interest because of the demand for low-cost nontoxic colloidal nanoprobes with high sensitivity and selectivity for various biomedical and environment-related applications. Carbon dots (CDs) are promising candidates for these applications as they demonstrate unique optical properties with intense emissions, biocompatibility, and ease of fabrication. Herein, we developed synthesis protocols to obtain CDs based on o-phenylenediamine with a variety of optical responses depending on additional precursors and changes in the reaction media.

Revealing the nature of optical activity in carbon dots produced from different chiral precursor molecules.

Carbon dots (CDs) are light-emitting nanoparticles that show great promise for applications in biology and medicine due to the ease of fabrication, biocompatibility, and attractive optical properties. Optical chirality, on the other hand, is an intrinsic feature inherent in many objects in nature, and it can play an important role in the formation of artificial complexes based on CDs that are implemented for enantiomer recognition, site-specific bonding, etc. We employed a one-step hydrothermal synthesis to produce chiral CDs from the commonly used precursors citric acid and ethylenediamine together with a set of different chiral precursors, namely, L-isomers of cysteine, glutathione, phenylglycine, and tryptophan.

Chiral carbon dots based on L/D-cysteine produced room temperature surface modification and one-pot carbonization.

Since chirality is one of the phenomena often occurring in nature, optically active chiral compounds are important for applications in the fields of biology, pharmacology, and medicine. With this in mind, chiral carbon dots (CDs), which are eco-friendly and easy-to-obtain light-emissive nanoparticles, offer great potential for sensing, bioimaging, enantioselective synthesis, and development of emitters of circularly polarized light. Herein, chiral CDs have been produced via two synthetic approaches using a chiral amino acid precursor l/d-cysteine: (i) surface modification treatment of achiral CDs at room temperature and (ii) one-pot carbonization in the presence of chiral precursor.

The influence of thermal treatment conditions (solvothermal versus microwave) and solvent polarity on the morphology and emission of phloroglucinol-based nitrogen-doped carbon dots.

The optical properties of chemically synthesized carbon dots (CDs) can be widely tuned via doping and surface modification with heteroatoms such as nitrogen, which results in a range of potential applications. Herein, two most commonly used synthesis approaches, namely, solvothermal and microwave-assisted thermal treatments, have been used for the preparation of CDs from phloroglucinol using three different nitrogen containing solvents, namely, ethylenediamine, dimethylformamide, and formamide. Based on the analysis of the morphology and optical properties, we demonstrate the tenability of the CD appearance from amorphous or well-carbonized spherical particles to onion-like ones, which is controlled by solvent polarity, whereas the thermal treatment conditions mostly influence the degree of N-doping and the nature of emissive centers of CDs formed.

Laser-Induced Deposition of Plasmonic Ag and Pt Nanoparticles, and Periodic Arrays.

Surfaces functionalized with metal nanoparticles (NPs) are of great interest due to their wide potential applications in sensing, biomedicine, nanophotonics, etc. However, the precisely controllable decoration with plasmonic nanoparticles requires sophisticated techniques that are often multistep and complex. Here, we present a laser-induced deposition (LID) approach allowing for single-step surface decoration with NPs of controllable composition, morphology, and spatial distribution.

Synthesis of the FeOOH Microtubes with Inner Surface Modified by Ag Nanoparticles.

Lepidocrocite (γ-FeOOH) microtubes with scroll morphology prepared by gas-solution interface technique (GSIT) have been modified by silver nanoparticles (Ag NPs). The successive ionic layer deposition (SILD) was first used for the synthesis of the Ag NPs on the lower surface of a solid film freely lying on the surface of a solution. The sizes of Ag NPs are about 15 nm after one synthesis cycle, and their diameters reach 35 nm after three SILD cycles.

Interface-Assisted Synthesis of Single-Crystalline ScF Microtubes.

Scandium fluoride (ScF) microtubes with nanoscale wall thickness were for the first time successfully synthesized by an interface-assisted technique at the surface of a scandium nitrate aqueous solution without the addition of any surfactant as a result of interaction with hydrofluoric acid from the gaseous phase in only 30 min. X-ray diffraction analysis, scanning electron microscopy, helium ionic microscopy, transmission electron microscopy (TEM), and high-resolution TEM (HRTEM) were used to examine the morphology and crystal structure of ScF microtubes. The results show that the ScF microtube is single-crystalline and has a hexagonal structure.