Calculation of the highly excited SF6 vibrational state distributions and dissociation yields in different gas mixtures

Influence of the buffer gas on the multiphoton absorption and dissociation in different mixtures was investigated. Simple method based on the empirical and theoretical vibrational energy distribution is applied for high fluence regime. Collisional effects of buffer gas (Ar) are introduced to enhance the absorption and relaxation of irradiated molecules (SF6 and C2H4). Functional dependences of mean number of absorbed photons per molecule ( LT n GT (total)) on the Molecular excitation level are presented, enabling us to confirm or predict the level of excitation, number of molecules directly involved in the absorption process and dissociated during the laser pulse.International School and Conference on Optics and Optical Materials, Sep 03-07, 2007, Belgrade, Serbi

Limitations of the generalized coupled two-level model during the multiphoton absorption in different gas mixtures

Generalized coupled two-level model is applied in different gas mixtures and investigated for high fluence regime. Functional dependences of mean number of absorbed photons per molecule LT n GT (total) on buffer-gas pressure (P-buff) are presented, used to confirm or predict some possible physical and chemical processes, like enhanced absorption and/or dissociation. Limitations of proposed models are analyzed depending on both gas pressure and laser fluence. Results are compared with other previously obtained by the same experimental technique, but for different absorbing molecule.International School and Conference on Optics and Optical Materials, Sep 03-07, 2007, Belgrade, Serbi

Polyacrilic Acid and Chitosan Assisted Solvothermal Synthesis of Up-converting NaYF4: Yb,Er Particles

There is a growing interest for development of a facile and reproducible approach for the synthesis of biocompatible lanthanide doped up-converting nanoparticles (UCNPs) for deep tissue imaging and targeted drug delivery. Synthesis of such particles is usually performed through the decomposition of organometallic compounds, followed either with a ligands exchange or with a biocompatible layer coating. In this work, biocompatible NaYF4:Yb,Er (17 mol% Yb; 3 mol% Er) nanoparticles were synthesized by one-pot hydrothermal processing with an assistance of chitosan (Ch) or polyacrylic acid (PAA). Obtained powders were analyzed by X-ray powder diffraction (XRPD, Bruker D8 Discovery), field emission scanning electron microscopy (FE-SEM, Zeiss, DSM 960), transmission electron microscopy (TEM, JEOL JEM 2010), Fourier transform infrared (FTIR, Thermo Scientific Nicolet 6700) and photoluminescence (PL, Spex Fluorolog with C31034 cooled photomultiplier) spectroscopy. The results showed that although both powders crystallize in the same crystal arrangement (cubic, Fm-3m), particles size, shape and optical properties are dependent on the polymer used

Polyacrilic Acid and Chitosan Assisted Solvothermal Synthesis of Up-converting NaYF4: Yb,Er Particles

There is a growing interest for development of a facile and reproducible approach for the synthesis of biocompatible lanthanide doped up-converting nanoparticles (UCNPs) for deep tissue imaging and targeted drug delivery. Synthesis of such particles is usually performed through the decomposition of organometallic compounds, followed either with a ligands exchange or with a biocompatible layer coating. In this work, biocompatible NaYF4:Yb,Er (17 mol% Yb; 3 mol% Er) nanoparticles were synthesized by one-pot hydrothermal processing with an assistance of chitosan (Ch) or polyacrylic acid (PAA). Obtained powders were analyzed by X-ray powder diffraction (XRPD, Bruker D8 Discovery), field emission scanning electron microscopy (FE-SEM, Zeiss, DSM 960), transmission electron microscopy (TEM, JEOL JEM 2010), Fourier transform infrared (FTIR, Thermo Scientific Nicolet 6700) and photoluminescence (PL, Spex Fluorolog with C31034 cooled photomultiplier) spectroscopy. The results showed that although both powders crystallize in the same crystal arrangement (cubic, Fm-3m), particles size, shape and optical properties are dependent on the polymer used

Polyacrilic Acid and Chitosan Assisted Solvothermal Synthesis of Up-converting NaYF4: Yb,Er Particles

There is a growing interest for development of a facile and reproducible approach for the synthesis of biocompatible lanthanide doped up-converting nanoparticles (UCNPs) for deep tissue imaging and targeted drug delivery. Synthesis of such particles is usually performed through the decomposition of organometallic compounds, followed either with a ligands exchange or with a biocompatible layer coating. In this work, biocompatible NaYF4:Yb,Er (17 mol% Yb; 3 mol% Er) nanoparticles were synthesized by one-pot hydrothermal processing with an assistance of chitosan (Ch) or polyacrylic acid (PAA). Obtained powders were analyzed by X-ray powder diffraction (XRPD, Bruker D8 Discovery), field emission scanning electron microscopy (FE-SEM, Zeiss, DSM 960), transmission electron microscopy (TEM, JEOL JEM 2010), Fourier transform infrared (FTIR, Thermo Scientific Nicolet 6700) and photoluminescence (PL, Spex Fluorolog with C31034 cooled photomultiplier) spectroscopy. The results showed that although both powders crystallize in the same crystal arrangement (cubic, Fm-3m), particles size, shape and optical properties are dependent on the polymer used

Orange-Reddish Light Emitting Phosphor GdVO 4 :Sm 3+ Prepared by Solution Combustion Synthesis

The gadolinium vanadate doped with samarium (GdVO 4 :Sm 3+ ) nanopowder was prepared by the solution combustion synthesis (SCS) method. After synthesis, in order to achieve the full crystallinity, the material was annealed in air atmosphere at 900°C. Phase identification in the postannealed powder samples was performed by X-ray diffraction, and morphology was investigated by high-resolution scanning electron microscopy (SEM). Photoluminescence characterization of the emission spectrum and time-resolved analysis have been performed using the tunable laser optical parametric oscillator excitation and the streak camera. Several strong emission bands in the Sm 3+ emission spectrum were observed, located at 567 nm ( 4 G 5/2 – 6 H 5/2 ), 604 nm ( 4 G 5/2 – 6 H 7/2 ), and 646 (654) nm ( 4 G 5/2 – 6 H 9/2 ), respectively. The weak emission bands at 533 nm ( 4 F 3/2 – 6 H 5/2 ) and 706 nm ( 4 G 5/2 – 6 H 11/2 ) and a weak broad luminescence emission band of VO 4 3− were also observed by the detection system. We analyzed the possibility of using the host luminescence for two-color temperature sensing. The proposed method is improved by introducing the temporal dependence in the line intensity ratio measurements

Nonlinear laser scanning microscopy for imaging of the cells labeled by upconverting NaYF4:Yb,Er nanoparticles

The Nonlinear Laser Scanning Microscopy (NLSM) contributes to the cell labeling through addressing two main issues: photobleaching and phototoxicity. Moreover, an increase of the penetration depth and a reduction of background autofluorescence are achieved.We have used a multidisciplinary approach combining expertise in material science, nanoparticles synthesis and characterization, cancer cell and tissue labeling, and high resolution imaging, in order to accomplish in vitro imaging of the cancer cells. We have imaged the oral squamous carcinoma cells and human gingival cells. We have demonstrated that we are able to take high contrast images. We have shown position of the nanoparticles in cells, through colocalization of the cell auto-fluorescence and the nanoparticles up-conversion.We plan to improve our abilities through further optimization of the up-converting nanoparticles (smaller and brighter particles) and microscopy technique

NIR photo-driven upconversion in NaYF4:Yb,Er/PLGA particles for in vitro bioimaging of cancer cells

Lanthanide-doped fluoride up-converting nanoparticles (UCNPs) represent the new class of imaging contrast agents which hold great potential for overcoming existing problems associated with traditionally used dyes, proteins and quantum dots. In this study, a new kind of hybrid NaYF4:Yb,Er/PLGA nanoparticles for efficient biolabeling were prepared through one-pot solvothermal synthesis route. Morphological and structural characteristics of the as-designed particles were obtained using X-ray powder diffraction (XRPD), scanning and transmission electron microscopy (SEM/TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy, while their cytotoxicity as well as up-conversion (UC) labeling capability were tested in vitro toward human gingival cells (HGC) and oral squamous cell carcinoma (OSCC). The results revealed coexistence of the cubic (Fm-3m) and hexagonal (P63/m) phase in spherical and irregularly shaped nanoparticles, respectively. PLGA [Poly(lactic-co-glycolic acid)] ligands attached at the surface of UCNPs particles provide their enhanced cellular uptake and enable high-quality cells imaging through a near-infrared (NIR) laser scanning microscopy (λex = 980 nm). Moreover, the fact that NaYF4:Yb,Er/PLGA UCNPs show low cytotoxicity against HGC over the whole concentration range (10–50 μg/mL) while a dose dependent viability of OSCC is obtained indicates that these might be a promising candidates for targeted cancer cell therapy. © 2018 Elsevier B.V.This is the peer reviewed version of the following article: Mancic, L., A. Djukic-Vukovic, I. Dinic, M.G. Nikolic, M.D. Rabasovic, A.J. Krmpot, A.M.L.M. Costa, et al. 2018. “NIR Photo-Driven Upconversion in NaYF4:Yb,Er/PLGA Particles for in Vitro Bioimaging of Cancer Cells.” Materials Science and Engineering C 91: 597–605. [https://doi.org/10.1016/j.msec.2018.05.081]Published version: [https://hdl.handle.net/21.15107/rcub_dais_3693]Supporting information: [https://hdl.handle.net/21.15107/rcub_dais_5978

Supplementary data for the article: Mancic, L.; Djukic-Vukovic, A.; Dinic, I.; Nikolic, M. G.; Rabasovic, M. D.; Krmpot, A. J.; Costa, A. M. L. M.; Marinkovic, B. A.; Mojovic, L.; Milosevic, O. One-Step Synthesis of Amino-Functionalized up-Converting NaYF 4 :Yb,Er Nanoparticles for: In Vitro Cell Imaging. RSC Advances 2018, 8 (48), 27429–27437. https://doi.org/10.1039/c8ra04178d

Supplementary material for: [https://doi.org/10.1039/c8ra04178d]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2225

Interactions of ultrashort laser pulses with hemoglobin: Photophysical aspects and potential applications

Hemoglobin (Hb), a life-sustaining and highly abundant erythrocyte protein, is not readily fluorescent. A few studies have already reported Two-Photon Excited Fluorescence (TPEF) of Hb, however, the mechanisms through which Hb becomes fluorescent upon interaction with ultrashort laser pulses are not completely understood. Here, we characterized photophysically this interaction on Hb thin film and erythrocytes using fluorescence spectroscopy upon single-photon/two-photon absorption, and UV-VIS single-photon absorption spectroscopy. A gradual increase of the fluorescence intensity, ending up with saturation, is observed upon prolonged exposure of Hb thin layer and erythrocytes to ultrashort laser pulses at 730 nm. When compared to protoporphyrin IX (PpIX) and oxidized Hb by H2O2, TPEF spectra from a thin Hb film and erythrocytes showed good mutual agreement, broad peaking at 550 nm, supporting hemoglobin undergoes degradation and that same fluorescent specie(s) originating from the heme moiety are generated. The uniform square shaped patterns of the fluorescent photoproduct exhibited the same level of the fluorescence intensity even after 12 weeks from the formation, indicating high photoproduct stability. We finally demonstrated the full potential of the formed Hb photoproduct with TPEF scanning microscopy towards spatiotemporally controlled micropatterning in HTF and single human erythrocyte labelling and tracking in the whole blood