Single up-conversion nanocrystal as a local temperature probe of electrically heated silver nanowire

Luminescence thermometry is a powerful technique for monitoring temperature in a sensitive, remote (through light), and minimally invasive manner. Up to now, many macroscopic and microscopic luminescence temperature probes exploiting different temperature sensing schemes have been investigated, with the majority of the studies using aggregates of nanothermometers. This work presents isolated single up-converting NaYF₄:Er³⁺/Yb³⁺ nanocrystals as functional temperature indicators operating in a standard confocal microscopy configuration. More specifically, the nanocrystals were used to monitor the temperature of a single silver nanowire, whose temperature was controlled electrically via the Joule process. We demonstrate that individual nanocrystals placed near the nanowire can precisely determine the temperature distribution in its surroundings. These results, which combine nanoscopic heat generation with temperature readout using isolated nanocrystals, represent an essential step for the application of isolated single nanoprobes for luminescence thermometry at the nanoscale.

Tip-enhanced Raman spectroscopy of bradykinin and its B2 receptor antagonists adsorbed onto colloidal suspended Ag nanowires

The tip-enhanced Raman scattering (TERS) spectra of bradykinin (BK) and its potent B2 BK receptor antagonists, [d-Arg(0),Hyp(3),Thi(5,8),l-Pip(7)]BK and [d-Arg(0),Hyp(3),Thi(5),d-Phe(7),l-Pip(8)]BK, approximately with a size of about 40 nm, adsorbed onto colloidal suspended Ag nanowires with diameter in the range of 350-500 nm and length of 2-50 μm were recorded. The metal surface plasmon resonance and morphology of the Ag nanowires were studied by ultraviolet-visible (UV-Vis) spectroscopy and scanning electron microscopy (SEM). Briefly, it was shown that two C-terminal amino acids of BK and [d-Arg(0),Hyp(3),Thi(5,8),l-Pip(7)]BK are involved in the interaction with the colloidal suspended Ag nanowire surface, whereas three last amino acids of the [d-Arg(0),Hyp(3),Thi(5),d-Phe(7),l-Pip(8)]BK sequence attached the Ag surface. Thus, BK adsorbs on the colloidal suspended Ag nanowires mainly through the Phe(5/8) ring (tilted orientation) and the one oxygen atom of the carboxylate group and the H2N-C-NH-CH2- fragment of Arg(9). In the case of [d-Arg(0),Hyp(3),Thi(5,8),l-Pip(7)]BK, the Thi(8) ring (through the lone electron pair on the sulfur atom) and the both oxygen atoms of the carboxylate group and the amine group of Arg(9) mainly participated in the interaction with the Ag nanowire surface. For [d-Arg(0),Hyp(3),Thi(5),d-Phe(7),l-Pip(8)]BK, the d-Phe(7) ring, the Pip(8) ring, and the Arg(9) side-chain assisted in the peptide interaction with the Ag surface. The obtained results emphasize the importance of the C-terminal part of these peptides in the adsorption process onto the colloidal suspended Ag nanowires.

Upconverting/magnetic: Gd2O3:(Er3+,Yb3+,Zn2+) nanoparticles for biological applications: effect of Zn2+ doping

Upconverting/paramagnetic Gd₂O₃:1% Er³⁺, 18% Yb³⁺ with Zn²⁺ nanoparticles (NPs) permits one to perform optical imaging.

Zn(1-x)Mg(x)Te nanowires grown by solid source molecular beam epitaxy

This paper reports on the epitaxial growth of single-crystalline ternary Zn(1-x)Mg(x)Te nanowires covering a broad compositional range of molar fraction 0≤x≤0.75. The nanowires were grown on (100), (110), and (111) GaAs substrates using a vapor-liquid-solid mechanism. Solid source molecular beam epitaxy and an Au-based nanocatalyst were used for these purposes. The composition of nanowires can be adjusted by changing the ratio of Mg to Zn molecular beam fluxes. Electron microscopy images show that the nanowires are smooth and slightly tapered. The diameters of the obtained nanowires are from 30 to 70 nm and their length is around 1 µm. X-ray diffraction analysis and transmission electron microscopy reveal that the nanowires have a zinc-blende structure throughout the whole range of obtained compositions, and have a [Formula: see text] growth axis. The Raman measurements reveal both the expected splitting and shift of phonon lines with increasing Mg content, thus proving the substitutional incorporation of Mg into metallic sites of the ZnTe lattice.