Single nickel-related defects in molecular-sized nanodiamonds for multicolor bioimaging: an ab initio study

Quantum Point Defects for Solid-State Laser Refrigeration

Herein, the role that point defects have played over the last two decades in realizing solid-state laser refrigeration is discussed. A brief introduction to the field of solid-state laser refrigeration is given with an emphasis on the fundamental physical phenomena and quantized electronic transitions that have made solid-state laser-cooling possible. Lanthanide-based point defects, such as trivalent ytterbium ions (Yb3+ ), have played a central role in the first demonstrations and subsequent development of advanced materials for solid-state laser refrigeration. Significant discussion is devoted to the quantum mechanical description of optical transitions in lanthanide ions, and their influence on laser cooling. Transition-metal point defects have been shown to generate substantial background absorption in ceramic materials, decreasing the overall efficiency of a particular laser refrigeration material. Other potential color centers based on fluoride vacancies with multiple potential charge states are also considered. In conclusion, novel materials for solid-state laser refrigeration, including color centers in diamond that have recently been proposed to realize the solid-state laser refrigeration of semiconducting materials, are discussed.

Hybrids made of defective nanodiamonds interacting with DNA nucleobases

The characteristics of hybrids made of a defective nanodiamond and a biomolecule unit are investigated in this work. Focus is given on the interaction between the nanodiamond and a DNA nucleobase. The latter is placed close to the former in two different arrangements, realizing different bonding types. The nanodiamond includes a negatively charged nitrogen-vacancy center and is hydrogen terminated. Using quantum-mechanical calculations, we could elucidate the structural and electronic properties of such hybrids. Our study clearly identifies the importance of the relative orientation of the two components, the nanodiamond and the nucleobase, in the complex in controlling the electronic properties of the resulting hybrid. The position of the defect at the center or closer to its interface with the nucleobase further controls the electronic orbitals around the defect center, hence its optical activity. In the end, we discuss the relevance of our work in biosensing.

Fast synthesis of fluorescent SiO2@CdTe nanoparticles with reusability in detection of H2O2

In this study, highly fluorescent core/shell SiO₂@CdTe nanoparticles (NPs) were synthesized conveniently and efficiently via a hydrothermal method. The as-prepared SiO₂@CdTe NPs were uniform with good fluorescence preservation. The SiO₂@CdTe NPs could be used for the rapid detection of H₂O₂ with good sensitivity within several minutes. Excellent linear relationships existed between the quenching degrees of the SiO₂@CdTe NPs and the concentration of H₂O₂ in the range of 0.005 mM to 0.1 mM. The limit of detection (LOD) for H₂O₂ was 10 nM. Furthermore, it was proved that SiO₂@CdTe NPs could be used repeatedly for H₂O₂ detection due to their easy separation, which is an important feature. The excellent performance of SiO₂@CdTe NPs should facilitate their applications in chemistry or biology for detection of H₂O₂.