-
Tiziana Passuello,
Marco Pedroni,
Fabio Piccinelli,
Stefano Polizzi,
Pasquina Marzola,
Stefano Tambalo,
Giamaica Conti,
Donatella Benati, Fiorenzo Vetrone,
Marco Bettinelli,
Adolfo Speghini
[show abstract]
[hide abstract]
ABSTRACT: A facile method for the synthesis of water dispersible Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) doped upconverting GdF(3) nanoparticles is reported. Strong upconversion emissions are observed in the red (for Er/Yb doped) and near-infrared (for Tm/Yb doped) regions upon laser excitation at 980 nm. The PEG coating ensures a good dispersion of the system in water and reduces the radiationless de-excitation of the excited states of the Er(3+) and Tm(3+) ions by water molecules. The r(2) relaxivity values are quite high with respect to the common T(2)-relaxing agents (22.6 ± 3.4 mM(-1) s(-1) and 15.8 ± 3.4 mM(-1) s(-1) for the Tm/Yb and Er/Yb doped samples, respectively), suggesting that the present NPs can be interesting as T(2) weighted contrast agents for proton MRI purpose. Preliminary experiments conducted in vitro, in stem cell cultures, and in vivo, after subcutaneous injection of the lanthanide-doped GdF(3) NPs, indicate scarce toxic effects. After an intravenous injection in mice, the GdF(3) NPs localize mainly in the liver. The present results indicate that the present Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) doped GdF(3) NPs are suitable candidates to be efficiently used as bimodal probes for both in vitro and in vivo optical and magnetic resonance imaging.
Nanoscale 11/2012; · 5.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The current status of luminescence nanothermometry is reviewed in detail. Based on the main parameters of luminescence including intensity, bandwidth, bandshape, polarization, spectral shift and lifetime, we initially describe and compare the different classes of luminescence nanothermometry. Subsequently, the various luminescent materials used in each case are discussed and the mechanisms at the root of the luminescence thermal sensitivity are described. The most important results obtained in each case are summarized and the advantages and disadvantages of these approaches are discussed.
Nanoscale 07/2012; 4(15):4301-26. · 5.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bis-spiropryran molecules were grafted onto the surface of upconverting nanoparticles. Fluorescence resonance energy transfer from the upconverting nanoparticles to the surface bis-spiropyran molecules triggered the transformation of the ring-closed bis-spiropyran to the ring-open bis-merocyanine forms.
Chemical Communications 06/2012; 48(58):7244-6. · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The white light emission of Tm3+/Yb3+/Ho3+-doped GdVO4 nanocrystals, following excitation with near-infrared light (λexc = 980 nm), via a multiphoton upconversion process is presented. Upconverted blue emission from the Tm3+ ions as well as green/red emissions from the Ho3+ ions contributes to the observed white light. The calculated Commission internationale de l'éclairage (CIE) color coordinates were calculated to be x = 0.34; y = 0.32 and lie at the center of the white region. Furthermore, the intensity of the upconverted white light was enhanced by the incorporation of monovalent Li+ ions into the GdVO4 matrix. An explanation for this enhancement is proposed based on X-ray diffraction and fluorescence lifetime measurements.
Optics Express 01/2012; 20(1):111-9. · 3.59 Impact Factor
-
Ning-Ning Dong,
Marco Pedroni,
Fabio Piccinelli,
Giamaica Conti,
Andrea Sbarbati,
Juan Enrique Ramírez-Hernández,
Laura Martínez Maestro,
Maria Carmen Iglesias-de la Cruz,
Francisco Sanz-Rodriguez,
Angeles Juarranz,
Feng Chen, Fiorenzo Vetrone,
John A Capobianco,
José García Solé,
Marco Bettinelli,
Daniel Jaque,
Adolfo Speghini
[show abstract]
[hide abstract]
ABSTRACT: In this study, we report on the remarkable two-photon excited fluorescence efficiency in the "biological window" of CaF(2):Tm(3+),Yb(3+) nanoparticles. On the basis of the strong Tm(3+) ion emission (at around 800 nm), tissue penetration depths as large as 2 mm have been demonstrated, which are more than 4 times those achievable based on the visible emissions in comparable CaF(2):Er(3+),Yb(3+) nanoparticles. The outstanding penetration depth, together with the fluorescence thermal sensitivity demonstrated here, makes CaF(2):Tm(3+),Yb(3+) nanoparticles ideal candidates as multifunctional nanoprobes for high contrast and highly penetrating in vivo fluorescence imaging applications.
ACS Nano 09/2011; 5(11):8665-71. · 10.77 Impact Factor
-
Small 05/2011; 7(13):1774-8. · 8.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The synthesis using the thermal decomposition of metal trifluoroacetates is being widely used to prepare oleate-capped lanthanide-doped upconverting NaYF(4):Er(3+)/Yb(3+) nanoparticles (Ln-UCNPs). These nanoparticles have no inherent aqueous dispersibility and inconvenient postsynthesis treatments are required to render them water dispersible. Here, we have developed a novel and facile approach to obtain water-dispersible, ligand-free, brightly upconverting Ln-UCNPs. We show that the upconversion luminescence is affected by the local environment of the lanthanide ions at the surface of the Ln-UCNPs. We observe a dramatic difference of the integrated upconverted red:green emission ratio for Ln-UCNPs dispersed in toluene compared to Ln-UCNPs dispersed in water. We can enhance or deactivate the upconversion luminescence by pH and H/D isotope vibronic control over the competitive radiative and nonradiative relaxation pathways for the red and green excited states. Direct biofunctionalization of the ligand-free, water-dispersible Ln-UCNPs will enable myriad new opportunities in targeting and drug delivery applications.
Nano Letters 02/2011; 11(2):835-40. · 13.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The intensity of high energy UV and blue upconverted emissions of Tm(3+) ions in Tm(3+)/Yb(3+) co-doped LiYF(4) colloidal nanocrystals was selectively reduced compared to the NIR emission at 802 nm. This was achieved by doping a small amount of Dy(3+) ions into the host matrix.
Chemical Communications 02/2011; 47(12):3481-3. · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The technological development of quantum dots has ushered in a new era in fluorescence bioimaging, which was propelled with the advent of novel multiphoton fluorescence microscopes. Here, the potential use of CdSe quantum dots has been evaluated as fluorescent nanothermometers for two-photon fluorescence microscopy. In addition to the enhancement in spatial resolution inherent to any multiphoton excitation processes, two-photon (near-infrared) excitation leads to a temperature sensitivity of the emission intensity much higher than that achieved under one-photon (visible) excitation. The peak emission wavelength is also temperature sensitive, providing an additional approach for thermal imaging, which is particularly interesting for systems where nanoparticles are not homogeneously dispersed. On the basis of these superior thermal sensitivity properties of the two-photon excited fluorescence, we have demonstrated the ability of CdSe quantum dots to image a temperature gradient artificially created in a biocompatible fluid (phosphate-buffered saline) and also their ability to measure an intracellular temperature increase externally induced in a single living cell.
Nano Letters 11/2010; · 13.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, we demonstrate for the first time that the new class of fluoride-based inorganic upconverting nanoparticles, NaYF4:Er3+, Yb3+, are the most efficient multiphoton excited fluorescent nanoparticles developed to date. The near-infrared-to-visible conversion efficiency of the aforementioned nanoparticles surpasses that of CdSe quantum dots and gold nanorods, which are the commercially available inorganic fluorescent nanoprobes presently used for multiphoton fluorescence bioimaging. The results presented here open new perspectives for the implementation of fluorescence tomography by multiphoton fluorescence imaging.
Optics Express 11/2010; 18(23):23544-53. · 3.59 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Water dispersible upconverting polyethylenimine (PEI)-capped NaYF(4) nanoparticles co-doped with trivalent erbium (Er(3+)) and ytterbium (Yb(3+)) were prepared via solvothermal synthesis with an 18 nm average particle diameter. These upconverting nanoparticles can be used to sensitize a light-harvesting phycobiliprotein (R-Phycoerythrin) via luminescence resonance energy transfer (LRET).
Nanoscale 07/2010; 2(7):1185-9. · 5.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Acquiring the temperature of a single living cell is not a trivial task. In this paper, we devise a novel nanothermometer, capable of accurately determining the temperature of solutions as well as biological systems such as HeLa cancer cells. The nanothermometer is based on the temperature-sensitive fluorescence of NaYF(4):Er(3+),Yb(3+) nanoparticles, where the intensity ratio of the green fluorescence bands of the Er(3+) dopant ions ((2)H(11/2) --> (4)I(15/2) and (4)S(3/2) --> (4)I(15/2)) changes with temperature. The nanothermometers were first used to obtain thermal profiles created when heating a colloidal solution of NaYF(4):Er(3+),Yb(3+) nanoparticles in water using a pump-probe experiment. Following incubation of the nanoparticles with HeLa cervical cancer cells and their subsequent uptake, the fluorescent nanothermometers measured the internal temperature of the living cell from 25 degrees C to its thermally induced death at 45 degrees C.
ACS Nano 06/2010; 4(6):3254-8. · 10.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report on the efficient incorporation of non-functionalized NaYF(4) : Er(3+), Yb(3+) nanoparticles inside HeLa live cancer cells by direct endocytosis. The efficient two-photon excited near-infrared-to-visible upconversion fluorescence of these nanoparticles is then used to obtain high-contrast intracellular fluorescence images of single cells. These images reveal a redistribution of the nanoparticles inside the cell as the incubation time increases. Thus, non-functionalized NaYF(4) : Er(3+), Yb(3+) nanoparticles emerge as very promising fluorescence probes for real-time imaging of cellular dynamics.
Nanoscale 04/2010; 2(4):495-8. · 5.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this study, monoclinic luminescent Gd2O3 nanocrystals doped with different concentrations of Er3+ (0.1, 1, and 10 mol%) were produced by propellant synthesis and flame spray pyrolysis (FSP). A comparison of their optical and morphological properties is reported. Following 980 nm excitation, an increase of the emission intensity from the 2H11/2, 4S3/2→ 4I15/2 and 4F9/2→ 4I15/2 transitions was observed with increasing Er 3+ concentration in the Gd2O3 nanocrystalline samples prepared via both techniques. However, the overall upconversion emission intensity was greater for the samples obtained by FSP. Furthermore, as the Er3+ concentration was increased, the intensity of the red ( 4F9/2&rarr4I15/2) emission was observed to increase more rapidly in comparison to the green (2H 11/2, 4S3/2&rarr4I15/2) emission resulting in an overall enhancement of the red component in the upconversion emission. Although both synthetic routes yield average crystallite sizes in the nanoscale, the TEM and SEM images conf
Materials Research Bulletin. 01/2010; 45(8):927-932.
-
Chemistry 08/2009; 15(38):9660-3. · 5.93 Impact Factor
-
Chemistry 07/2009; 15(38):9660 - 9663. · 5.93 Impact Factor
-
Advanced Functional Materials 07/2009; 19(18):2924 - 2929. · 10.18 Impact Factor
-
Advanced Materials 06/2009; 21(40):4025 - 4028. · 13.88 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Tetragonal barium yttrium fluoride (BaYF5) nanocrystals doped with 0.5 mol % Tm3+ and 15 mol % Yb3+ (BaYF5:Tm3+, Yb3+) were synthesized using the thermal decomposition method yielding rectangular-shaped nanocrystals (15 nm × 5 nm) that can (up)convert near-infrared light to higher energies such as blue, via a process known as upconversion. The upconversion spectrum of the BaYF5:Tm3+, Yb3+ nanocrystals, following excitation with 980 nm, revealed that the upconverted blue emission from the 1G4 → 3H6 transition was more intense than the infrared 3H4 → 3H6 emission at high excitation densities (90 W/cm2) contrary to what is normally observed for Tm3+/Yb3+ codoped nanomaterials. On the other hand, the infrared emission dominates at lower excitation densities (15 W/cm2) demonstrating a lack of excited Yb3+ ions to carry on the upconversion beyond the 3H4 excited state to the 1G4 excited state. A saturation of the upconversion process was observed in the power dependence studies at excitation densities above 57 W/cm2, causing a deviation in the expected number of photons required for the upconversion process. The upconversion properties of BaYF5:Tm3+, Yb3+ nanocrystals are elucidated and discussed.
05/2009;
-
Fabio Variola, Fiorenzo Vetrone,
Ludovic Richert,
Pawel Jedrzejowski,
Ji-Hyun Yi,
Sylvia Zalzal,
Sylvain Clair,
Andranik Sarkissian,
Dmitrii F Perepichka,
James D Wuest,
Federico Rosei,
Antonio Nanci
[show abstract]
[hide abstract]
ABSTRACT: The human body is an intricate biochemical-mechanical system, with an exceedingly precise hierarchical organization in which all components work together in harmony across a wide range of dimensions. Many fundamental biological processes take place at surfaces and interfaces (e.g., cell-matrix interactions), and these occur on the nanoscale. For this reason, current health-related research is actively following a biomimetic approach in learning how to create new biocompatible materials with nanostructured features. The ultimate aim is to reproduce and enhance the natural nanoscale elements present in the human body and to thereby develop new materials with improved biological activities. Progress in this area requires a multidisciplinary effort at the interface of biology, physics, and chemistry. In this Review, the major techniques that have been adopted to yield novel nanostructured versions of familiar biomaterials, focusing particularly on metals, are presented and the way in which nanometric surface cues can beneficially guide biological processes, exerting influence on cellular behavior, is illustrated.
Small 05/2009; 5(9):996-1006. · 8.35 Impact Factor
