Trapping and patterning of biological objects using photovoltaic tweezers

Photovoltaic tweezers are a recently proposed technique for manipulation and patterning of micro- and nano-objects. It is based in the dielectrophoretic forces associated to the electric fields induced by illumination of certain ferroelectrics due to the bulk photovoltaic effect. The technique has been applied to the patterning of dielectric and metal micro- and nano-particles. In this work, we report the use of photovoltaic tweezers to pattern biological objects on LiNbO3:Fe. Specifically, spores and pollen grains and their nanometric fragments have been trapped and patterned. 1D and 2D arrangements have been achieved by deposition in air or from a hexane suspension. The quality of patterns obtained with nanometric fragments is even better than previous results using photovoltaic tweezers with inorganic micro- and nano-particles. In fact, 1D patterns with a period of 2 μm, almost half of the minimum reported period achieved with photovoltaic tweezers, have been obtained with pollen fragmentsThis work was supported by Spanish projects MAT2011-28379-C03 and MAT2014-57704-C0

Diffractive optical devices produced by light-assisted trapping of nanoparticles

© 2015 Optical Society of America.]. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibitedOne and two-dimensional diffractive optical devices have been fabricated by light assisted trapping and patterning of nanoparticles. The method is based on the dielectrophoretic forces appearing in the vicinity of a photovoltaic crystal, such as Fe:LiNbO3, during or after illumination. By illumination with the appropriate light distribution, the nanoparticles are organized along patterns designed at will. One- and two-dimensional diffractive components have been achieved on X- and Z-cut Fe:LiNbO3 crystals, with their polar axes parallel and perpendicular to the crystal surface, respectively. Diffraction gratings with periods down to around a few micrometers have been produced using metal (Al, Ag) nanoparticles with radii in the range of 70-100 nm. Moreover, several 2D devices, such as Fresnel zone plates, have been also produced showing the potential of the method. The diffractive particle patterns remain stable when light is removed. A method to transfer the diffractive patterns to other non-photovoltaic substrates, such as silica glass, has been also reportedThis work was supported by Spanish projects MAT2011- 28379-C03 and MAT2014-57704-C0

Particle Patterning on Lithium Niobate waveguides via photovoltaic tweezers

Successful micro and nano-particle patterning on iron doped lithium niobate waveguides using photovoltaic fields is reported. This technique previously used in bulk crystals is here applied to waveguide configuration. Well defined particle patterns are obtained using two types of planar waveguides (by proton exchanged and swift heavy ion irradiation) and metallic and dielectric neutral particles. The use of waveguide configuration has allowed a reduction of the light exposure time until 3 s, two orders of magnitude smaller than typical values used in bulk

Analysis and optimization of propagation losses in LiNbO3 optical waveguides produced by swift heavy-ion irradiation

The propagation losses (PL) of lithium niobate optical planar waveguides fabricated by swift heavy-ion irradiation (SHI), an alternative to conventional ion implantation, have been investigated and optimized. For waveguide fabrication, congruently melting LiNbO3 substrates were irradiated with F ions at 20 MeV or 30 MeV and fluences in the range 1013–1014 cm−2. The influence of the temperature and time of post-irradiation annealing treatments has been systematically studied. Optimum propagation losses lower than 0.5 dB/cm have been obtained for both TE and TM modes, after a two-stage annealing treatment at 350 and 375∘C. Possible loss mechanisms are discussed

Caracterización de áridos volcánicos de Canarias y aplicaciones en la construcción de carreteras

[Resumen:] Debido a su formación geológica, en los archipiélagos de la Macaronesia los áridos utilizados son siempre de naturaleza volcánica, bien procedentes de los depósitos piroclásticos (basálticos y sálicos), bien de la fragmentación de rocas volcánicas (basaltos, traquitas, fonolitas e ignimbritas). Algunas de estas litologías, especialmente los basaltos masivos, suelen proporcionar áridos con buenas propiedades mecánicas debido a su elevada densidad y resistencia. Sin embargo, con frecuencia, las rocas volcánicas suelen presentar estructuras alveolares y escoriáceas muy porosas, asociadas a la elevada velocidad de descompresión y de enfriamiento. En ocasiones, estos materiales han experimentado un importante proceso de alteración hidrotermal, por la prolongada exposición a un foco magmático activo. Además, su distribución espacial muestra una elevada heterogeneidad, debido a la escasa continuidad lateral de los materiales, incluso dentro de un mismo yacimiento. Por último, los valores de sus propiedades físicas ofrecen una gran dispersión estadística, debido al carácter aleatorio que tiene la fábrica mineral de las coladas. Todo ello condiciona que las propiedades de los áridos resultantes sean más variables y su calidad más heterogénea que en territorios continentales. Por otra parte, las publicaciones sobre estos materiales son escasas y los pliegos normativos no incluyen especificaciones adaptadas a estos litotipos volcánicos. Por estos motivos, se han recopilado datos experimentales de las propiedades mecánicas en roca matriz y en áridos resultantes y se ofrecen experiencias sobre el empleo de éstos áridos en la construcción de carreteras. Esto proporciona valores de referencia para establecer correlaciones entre propiedades básicas y mejorar su caracterización. También se ofrecen recomendaciones para sus aplicaciones y para la adaptación de las especificaciones normativas vigentes.Ministerio de Economía y Competitividad; BIA2013-47987-C3-3-

Efficient photo-induced dielectrophoretic particle trapping on Fe:LiNbO3 for arbitrary two dimensional patterning

1D and 2D patterning of uncharged micro- and nanoparticles via dielectrophoretic forces on photovoltaic z-cut Fe:LiNbO3 have been investigated for the first time. The technique has been successfully applied with dielectric micro-particles of CaCO3 (diameter d = 1-3 ?m) and metal nanoparticles of Al (d = 70 nm). At difference with previous experiments in x- and y-cut, the obtained patterns locally reproduce the light distribution with high fidelity. A simple model is provided to analyse the trapping process. The results show the remarkably good capabilities of this geometry for high quality 2D light-induced dielectrophoretic patterning overcoming the important limitations presented by previous configurations

Preclinical Efficacy of Endoglin-Targeting Antibody–Drug Conjugates for the Treatment of Ewing Sarcoma

[EN] Endoglin (ENG; CD105) is a coreceptor of the TGFb family that is highly expressed in proliferating endothelial cells. Often coopted by cancer cells, ENG can lead to neo-angiogenesis and vasculogenic mimicry in aggressive malignancies. It exists both as a transmembrane cell surface protein, where it primarily interacts with TGFb, and as a soluble matricellular protein (sENG) when cleaved by matrix metal-loproteinase 14 (MMP14). High ENG expression has been associated with poor prognosis in Ewing sarcoma, an aggressive bone cancer that primarily occurs in adolescents and young adults. However, the therapeutic value of ENG targeting has not been fully explored in this disease. Experimental Design: We characterized the expression pattern of transmembrane ENG, sENG, and MMP14 in preclinical and clinical samples. Subsequently, the antineoplastic potential of two novel ENG-targeting monoclonal antibody–drug conjugates (ADC), OMTX503 and OMTX703, which differed only by their drug payload (nigrin-b A chain and cytolysin, respectively), was assessed in cell lines and preclinical animal models of Ewing sarcoma. Results: Both ADCs suppressed cell proliferation in proportion to the endogenous levels of ENG observed in vitro. Moreover, the ADCs significantly delayed tumor growth in Ewing sarcoma cell line–derived xenografts and patient-derived xenografts in a dose-dependent manner. Conclusions: Taken together, these studies demonstrate potent preclinical activity of first-in-class anti-ENG ADCs as a nascent strategy to eradicate Ewing sarcoma