Influence of chemical treatment and interaction with matrix on room temperature phosphorescence of carbon dots.

In this work, composite materials were formed based on various matrices (polymer and porous cellulose matrix) and carbon dots (CDs) with intense room-temperature phosphorescence (RTP). The effect of post-synthesis chemical treatment with citric acid or urea on the optical properties of composites was studied: the increase in carboxy and carbonyl groups led to an increase of RTP signals that could be seen with the naked eye over several seconds. The fabricated composites demonstrated good stability and reversibility of RTP signals by mild heating.

Green and Red Emissive N,O-Doped Chiral Carbon Dots Functionalized with l-Cysteine.

Although chirality plays an important role in the natural world, it has also attracted much scientific attention in nanotechnology, in particular, spintronics and bioapplications. Chiral carbon dots (CDs) are promising nanoparticles for sensing and bioimaging since they are biocompatible, ecofriendly, and free from toxic elements. Herein, green and red emissive chiral CDs are fabricated via surface modification treatment of achiral CDs at room temperature.

Energy-level engineering of carbon dots through a post-synthetic treatment with acids and amines.

Chemically synthesized carbon dots (CDs) have attracted a lot of attention as an eco-friendly and cost-efficient light-emitting material, and functionalization of CD surfaces with additives of different natures is a useful way to control their properties. In this study, we show how a post-synthetic treatment of CDs with citric acid, benzoic acid, urea and -phenylenediamine changes their chemical composition and optical properties. In particular, it results in the formation of carboxyl/imide/carbonyl groups at the CD surface, leading to the appearance of additional blue (or for CDs treated with phenylenediamine, blue and green) emissive optical centers on top of the remaining emission from the original CDs.

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.

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.

Carbon Dots with an Emission in the Near Infrared Produced from Organic Dyes in Porous Silica Microsphere Templates.

Carbon dots (CDs) with an emission in the near infrared spectral region are attractive due to their promising applications in bio-related areas, while their fabrication still remains a challenging task. Herein, we developed a template-assisted method using porous silica microspheres for the formation of CDs with optical transitions in the near infrared. Two organic dyes, Rhodamine 6G and IR1061 with emission in the yellow and near infrared spectral regions, respectively, were used as precursors for CDs.

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.

Strongly Luminescent Composites Based on Carbon Dots Embedded in a Nanoporous Silicate Glass.

Luminescent composites based on entirely non-toxic, environmentally friendly compounds are in high demand for a variety of applications in photonics and optoelectronics. Carbon dots are a recently developed kind of luminescent nanomaterial that is eco-friendly, biocompatible, easy-to-obtain, and inexpensive, with a stable and widely tunable emission. Herein, we introduce luminescent composites based on carbon dots of different chemical compositions and with different functional groups at the surface which were embedded in a nanoporous silicate glass.

Influence of the solvent environment on luminescent centers within carbon dots.

Carbon dots (CDs) are luminescent nanomaterials, with potential use in bioimaging and sensorics. Here, the influence of the surrounding solvent media on the optical properties of CDs synthesized from the most commonly employed precursors, namely citric acid and ethylenediamine, is investigated. The position of optical transitions of CDs can be tuned by the change of pH and solvent polarity.

Luminescence enhancement of alloyed quantum dots bound to gold nanoparticles by mercaptocarboxylic acids in colloidal complexes.

The understanding of the physical mechanisms of the nanoobjects interaction within the nanostructured complex materials is one of the main tasks for the development of novel materials with tunable properties. In this work, we develop a formation procedure of the colloidal complexes based on alloyed CdZnSe/ZnS quantum dots and gold nanoparticles where the various mercaptocarboxylic acids are used as the binding molecules. The QD photoluminescence enhancement (up to ×3.