The need for new electronic devices and applications is driving the use of transition metal dichalcogenides (TMDCs) as suitable materials to integrate the next generation of novel applications. Thickness control of semiconductors is the great importance to attain specific electrochemical properties. In this work we investigate the thickness fluctuation of 2D MoSe2 structures synthesized by pulsed laser ablation in liquids (PLAL) by changing the choice of liquid phase. For the characterization we used atomic absorption spectrometer, high resolution electron microscopy, Raman spectroscopy and photoluminescence spectroscopy. Thinner MoSe2 nanosheets resulted from PLAL synthesis in reline compared with those produced in water.
Biocompatible colloidal nanomaterials are of great interest in the biomedical field due to their ability to modulate redox reactions that translates into antioxidant aides. Common wet syntheses processes utilized to obtain chalcogens nanoparticles have limitations such as low yield, high cost and use environmentally unfriendly chemical precursors and solvents. Pulsed laser ablation in liquids (PLAL) has shown to be an affordable, clean and rapid technique to produce chalcogen nanoparticles. Among the chalcogens, selenium (Se) has well-known capabilities of regulating the glutathione to reduced glutathione (GSH/GSSG) ratio, an established marker of ROS antioxidant activity in eukaryotic cells. Recently there has been an interest to include heavier chalcogens, e.g., tellurium (Te), in biological enzymatic interactions; however, due to its relative cytotoxicity, use of Te nanoparticles as an alternative to reduce glutathione, has not been fully investigated. In this work, we introduce the synthesis and characterization of a selenium-tellurium (SeTe) nano-alloy by PLAL using a deep eutectic solvent (DES), water and acetone as the liquid phase to exploit DES’s biocompatible composition and its influence on the PLAL synthesis kinetics that result in production of polycrystalline, sub-100nm nanoparticles. To investigate the formation of nano-alloy, we compare the features and properties of colloidal nanoparticles produced by PLAL at three wavelengths, 1064, 532 and 355 nm, respectively. We test bioactivity of SeTe nano-alloys, using A-375 (malignant melanoma) and C-33A (epithelial retinoblastoma) cells through assessing viability and proliferation to determine their capabilities towards use as anticancer treatments.
Lanthanide doped upconversion nanoparticles (UCNPs) are promising luminescent materials for biomedical applications due to their ability to convert low energy, non-scattering NIR light to higher energy wavelength emissions. Sensing, bioimaging, drug delivery, therapy and photobiomodulation are the expected biomedical fields that will be impacted by the combination of NIR stimulation and upconversion emission. In the case of a typical upconversion from NIR, energy transfer occurs from Yb3+ sensitizer ions, which can be excited at 980 nm, to the activator lanthanide ions such as Er3+, Tm3+, Ho3+, Eu3+. Synthesis and design of the UCNPs and their introduction into the biological system requires stringent procedures due to the complex nature of biological environment at the cellular level. Our goal in this study is to develop small size, biocompatible UCNPs with a facile microwave assisted synthesis method and utilize them for photobiomodulation of neuronal cells. We aim to elucidate the intracellular mechanisms that are impacted by the upconversion photons emitted from designed nanotransducers towards stimulation of cell function. For this purpose, we sensitized blue emitting NaYF4 UCNPs and in-vitro laser irradiation experiments are conducted with NG108-15 (neuroblastoma-glioma hybrid) cells. Experiments are designed to further investigate the thermal and chemical effects that contribute to the resulted modifications in the cell function.
Inorganic fluorescent nanoprobes have been widely used as passive agents for intracellular imaging for decades. An emerging field of research is the development of these contrast agents and using them actively in a way that they respond to external stimulation by inducing photo-chemical, thermal or mechanical actions that enable control and modulation over cell function. To achieve such control, methods which are remote, non-invasive and with low-thermal means of stimulation is preferable. Among a large variety of candidates, lanthanide doped upconverting nanoparticles (UCNPs) are one of the most interesting class of fluorescent materials. Non-scattering, low energy near infrared (NIR) light can be used for excitation of UCNPs as on-demand light sources resulting in emission peaks throughout the near-UV and visible wavelengths. Towards this goal, we developed nano-size, hydrophilic, non-toxic and biocompatible core-shell nanoparticles with enhanced upconversion intensity for photo-biomodulation studies. Under this approach, un-doped LaF3 (inert) shell and Yb3+ doped LaF3 (active) shell are grown on core LaF3:20% Yb, 2% Tm upconverting nanoparticles for enhanced luminescence for the first time with rapid microwave-assisted synthesis method that employs Polyvinylpyrrolidone (PVP) as biocompatible surfactant. The as-synthesized high efficiency UCNPs are analyzed through XRD, TEM, HRTEM, and Photoluminescence spectrum that is acquired under 980 nm laser excitation. Confocal microscopy is used to visualize nanoparticles in cells. The cellular response to NIR irradiation and upconverted light are visualized by luminescence microscopy.
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