Functionalized nanoparticles are important analytical tool for biomedical applications. Pulsed laser ablation of bulk targets in an aqueous media is the one-step method for the fabrication, size manipulation and biofunctionalization of nanoparticles. We performed kHz laser ablation of a silver target by nanosecond pulses in tetramethylammonium hydroxide (TMAH) and sodium dodecyl sulfate (SDS) aqueous solutions to prepare silver nanoparticles. It was shown that the formation efficiency was increased by addition of TMAH and SDS as well as the stability of nanoparticles. The size decrease of the nanoparticles by addition of SDS was more remarkable than in the laser ablation in TMAH aqueous solutions. Emitted nanoparticles interact with TMAH and SDS in the secondary laser irradiation process leads to the nanoparticles stabilization in aqueous solutions.
We report on the deep-tissue imaging using novel upconversion nanoparticles (UCNPs) β-NaYF<sub>4</sub>:Yb<sup>3+</sup> ,Tm<sup>3+</sup> (excitation wavelength: 975 nm, detection wavelength: 800 nm) and glycerol as an optical clearing agent to enhance imaging from under 6-mm-thick porcine muscle tissue samples. We show that improvement of luminescent label visualization is caused by transforming of the diffuse label-emitted light into the direct component. This results in the increase in visibility (ratio of the sum and difference of the maximal and minimal intensity) of the label and increase in maximal signal intensity thus making the combination of the phosphors and optical clearing promising for precise detection of tissue-embedded labelled inhomogeneities.
In this paper, an overview of selected applications of semiconductor (TiO<sub>2</sub> and ZnO) and upconversion nanoparticles is presented. Depending on the size, the former are used as scattering and absorbing compounds in sunscreens and tissuemimicking phantoms; and in combination with gypsum – also as an antibacterial coating for indoor premises, while the latter, especially in combination with optical clearing – as a promising component for deep-biotissue imaging both in vitro and in vivo.
We report on the high-resolution deep-tissue imaging using novel water-dispersible upconversion nanoparticles (UCNPs)
β-NaYF<sub>4</sub>:Yb<sup>3+:</sup>Tm<sup>3+</sup>. Luminescence from the UCNP embedded into tissue-mimicking phantoms at the depth of 4 mm epi-illuminated with 975-nm laser radiation was detected. Fiber-optic detection shows 2-times better resolution compared with that obtained using CCD-based imaging modality. The conversion efficiency of upconversion particles and their cytotoxicity to HeLa cells were also investigated and reported.
The Mg<sub>0.27</sub>Zn<sub>0.73</sub>O/ZnO multiple quantum wells with different well width Lw have been grown by pulsed laser
deposition method. The interface roughness of quantum wells was inherited from the bottom one and did not exceed 1
nm. The quantum confinement effect has been observed. The exciton binding energy of the two-dimensional
Mg<sub>0.27</sub>Zn<sub>0.73</sub>O/ZnO structures was two times higher in comparison with the bulk ZnO. A sharp increase of exciton peak
intensity in the photoluminescence spectra at well width reduction was observed. The optical excited stimulated
emission in quantum wells Mg <sub>0.27</sub>Zn<sub>0.73</sub>O/ZnO with an excitation threshold ~210 kW/cm<sup>2</sup> has been demonstrated.