Bioactivation of zirconia surface with laminin protein coating via plasma etching and chemical modification

Surface modification offers a promising alternative to provide bioactivity to implanted inert biomaterials, improving their integration and performance with living tissues. In this contribution, zirconia has been used as a substrate to investigate the biofunctionalization process, designed to add surface bioactivity to a bioinert biomaterial. We intended to attach laminin-5, known for its ability to bind epithelial cells in soft tissue, to the surface of the extracellular matrix protein. First, the zirconia surface was etched and activated with argon plasma and subsequently it was chemically functionalized with calcium and phosphate ions. Zirconia surface activation was monitored by means of a wettability test, whereas functionalization with calcium and phosphate ions was evaluated by confocal Raman microscopy, Z-potential and X-ray Photoelectron Spectroscopy (XPS). The binding of laminin-5 protein to the zirconia surface was carried out by means of adsorption and confirmed by XPS. Then, we used SEM and AFM to observe a homogeneous covering of globular protein over the zirconia surface. Furthermore, epithelial cell response over zirconia surfaces was assayed to show that biofunctionalized surfaces enhance cell adhesion to a greater extent than substrates without protein coating. Our results indicate how the zirconia surface can be modified using argon plasma, in order to enable its bioactivation with the laminin-5 protein

In-Situ Preparation of CdTe Quantum Dots Capped with a β-Cyclodextrin-Epichlorohydrin Polymer: Polymer Influence on the Nanocrystal’s Optical Properties

β-Cyclodextrin (βCD), the less water soluble of the cyclodextrins, has been used as a capping agent in the preparation of semiconductor nanocrystals or quantum dots (QDs). Nevertheless, no reports have been found in the use of the highly water-soluble polymer of this, prepared by the crosslinking of the βCD units with epichlorohydrin in basic medium (βCDP). This polymer, besides to overcome the low solubility of the βCD, increases the inclusion constant of the guest; two parameters that deserve its use as capping agent, instead of the native cyclodextrin. In the present manuscript, we afforded the in-situ aqueous preparation of cadmium telluride (CdTe) QDs capped with βCDP. The polymer influence on the photoluminescent properties of the nanocrystals was analyzed. The βCDP controls the nanocrystals growth during the Oswald ripening stage. Consequently, the CdTe capped βCDP QDs showed lower Stokes-shift values, higher photoluminescent efficiency, and narrower size distribution than for nanocrystals obtained in the absence of polymer. Transmission electron microscopy (TEM) micrographs and energy dispersive X-ray spectroscopy (EDS) analysis revealed the composition and crystallinity of the CdTe QDs. This βCDP capped CdTe QDs is a potential scaffold for the supramolecular modification of QDs surface

Naica’s giant crystals: Deterioration scenarios

The Cave of Giant Crystals of Naica (Chihuahua, Mexico) is a world geological treasure worth to be preserved. These crystals of up to 12 m in length are made of selenite, the macrocrystalline variety of gypsum (CaSO4·2H2O). They have grown for thousands of years until the cave was dried, which allowed the cave and the crystals to be accessible, but exposed their surfaces in contact with air. Gypsum crystals are fragile because of their trend to dehydrate, the possible replacement to CaCO3 upon reactions with atmospheric CO2 as well as their intrinsic mechanical properties. Several laboratory experiments, designed to study the deterioration of selenite crystals under different artificial atmospheric conditions, are presented. Four atmospheric compositions rich in CO2, CH4, NOx, and air were tested for 1 year at temperatures of 25 and 60 °C and in either liquid or gaseous environments. The surface evolution was monitored by optical microscopy, infrared spectrometry, and grazing incidence X-ray diffraction with two-dimensional detectors. Surface alteration and dissolution in a water environment were observed in short exposition times, as well as the formation of bassanite (CaSO4·1/2H2O). Neither anhydrite nor calcite was detected. The gaseous environment constituted the most detrimental conditions to the gypsum crystals integrity.The authors would like to acknowledge Consejo Nacional de Ciencia y Tecnologia (grant number 183706); Industrias Peñoles for the support given to the experiments; A. Reyes-Rojas, D. Burciaga-Valencia, and E. Guerrero-Lastarjette for their continuous support in the realization of this project; and B. Aldea-Ballano and the team of the Chemical and Physicochemical Testing Unit in Instituto Eduardo Torroja de Ciencias de la Construcción in Madrid. The authors especially thank J. M. García-Ruiz for the suggestions of some experiments. Part of the experiments was performed (as part of Proposal No. 3939) at the Stanford Synchrotron Radiation Lightsource (SSRL), a Directorate of SLAC National Accelerator Laboratory and an Office of Science User Facility operated for the U.S. Department of Energy, Office of Science, by Stanford University.Peer reviewe

Do the Naica giant crystals deteriorate due to human sction?

Resumen del trabajo presentado al 25th international Congress on X-ray optic and microanalysis (ICXOM), celebrado en EE.UU. del 5 al 9 de agosto de 2019.The support given by CONACYT Project No. 183706 and by SSRL, ELETTRA, ESRF synchrotron facilities is acknowledged. Authors are thankful to Cia. Peñoles and Naica Mine for providing samples