Heterogeneous Catalysis through Microcontact Printing

Here, we investigate four different chemical pathways (Scheme 1a–d) relevant to the Cu-catalyzed azide–alkyne cycloaddition (CuAAC) reaction.[13] Three of those pathways lead to surfaces functionalized with organic molecules.[5, 11, 14] At the outset, our practical goal was to identify surface-functionalization protocols that are capable of attaining 1) spatial selectivity, 2) high surface coverage, and 3) rapid reaction kinetics. Our ultimate goal is to achieve a fundamental understanding of how different reaction pathways influence the chemical outcome as it applies to the organic functionalization of surfaces

Covalent microcontact printing of biomolecules

Soft lithography offers great potential for the fabrication of 2D and 3D patterned structures using a variety of materials and patterns. It complements and extends conventional fabrication methods. This thesis is particularly focus on microcontact printing (μCP) as a\ud method to create biological patterns on surfaces and also as a tool used in “in-situ” synthesis.\ud Microcontact printing has unique features that make this technique very attractive: (i) it is simple to introduce in any laboratory, (ii) it is biocompatible, (iii) it can fabricate features below 100 nm, (iv) it is applicable to broad range of materials, (v) it is efficient and not expensive. The important feature is that stamp which is used for printing is flexible and can seal conformally to\ud the surface tolerating the nanoscale roughness. In this thesis the focus is on the application of soft lithography in the fabrication of microsystems useful in studying interactions between biomolecules and cells

Growth factor release from a chemically modified elastomeric poly(1,8‐octanediol‐co‐citrate) thin film promotes angiogenesis in vivo

The ultimate success of in vivo organ formation utilizing ex vivo expanded “starter” tissues relies heavily upon the level of vascularization provided by either endogenous or artificial induction of angiogenic or vasculogenic events. To facilitate proangiogenic outcomes and promote tissue growth, an elastomeric scaffold previously shown to be instrumental in the urinary bladder regenerative process was modified to release proangiogenic growth factors. Carboxylic acid groups on poly(1,8‐octanediol‐co‐citrate) films (POCfs) were modified with heparan sulfate creating a heparan binding POCf (HBPOCf). Release of proangiogenic growth factors vascular endothelial growth factor (VEGF), fibroblast growth factor 2 (FGF2), and insulin‐like growth factor 1 (IGF‐1) from HBPOCfs demonstrated an approximate threefold increase over controls during a 30‐day time course in vitro . Atomic force microscopy demonstrated significant topological differences between films. Subcutaneous implantation of POCf alone, HBPOCf, POCf‐VEGF, and HBPOCf‐VEGF within the dorsa of nude rats yielded increased vascular growth in HBPOCf‐VEGF constructs. Vessel quantification studies revealed that POCfs alone contained 41.1 ± 4.1 vessels/mm 2 , while HBPOCf, POCf‐VEGF, and HBPOCF‐VEGF contained 41.7 ± 2.6, 76.3 ± 9.4, and 167.72 ± 15.3 vessels/mm 2 , respectively. Presence of increased vessel growth was demonstrated by CD31 and vWF immunostaining in HBPOCf‐VEGF implanted areas. Data demonstrate that elastomeric POCfs can be chemically modified and possess the ability to promote angiogenesis in vivo . © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90248/1/33306_ftp.pd

Changes in soil use in the lands of the sugar refinery of Las Palmas, province of Chaco, during the years 1987 and 2001

En el departamento Bermejo, provincia de Chaco, a fines del siglo XIX se origina uno de los ingenios azucareros más importantes del país: las Palmas del Chaco Austral S.A. En la década de los noventa es víctima de las políticas de privatización imperantes del momento. Como consecuencia, se produce su cierre y posterior desaparición, lo que supuso la eliminación de la principal fuente de trabajo de la localidad. Las tendencias actuales y novedosas en teledetección, cartografía digital y Sistemas de información Geográfica (SIG) son una forma útil e importante de ofrecer conocimientos actualizados para el diagnóstico, monitoreo y su aplicación en la gestión e investigación de recursos presentes en los distintos lugares de nuestro país. En el presente trabajo se pretende analizar los cambios producidos en el uso de suelo en las tierras del ex Ingenio a partir del cierre del mismo, mediante el uso de imágenes satelitales de los años 1987 y 2001, y de sistemas de información geográfica (SIG). El análisis multiespectral y multitemporal de las mismas permitirá discriminar los tipos de cobertura del suelo sobre la base de su respuesta espectral.One of the most important sugar refineries of Argentina was established at the end of the 19 th Century, in the Bermejo region, province of Chaco: Las Palmas del Chaco Austral S.A. During the 1990s it fell victim to the mayor privatization policies of the time, as a consequence of which it closed down and ultimately vanished, eliminating the main source of labor in the city. Current innovative trends in teledetection, digital cartography and Geographic Information Systems (GIS) are useful and important ways to offer up-todate knowledge in order to carry out diagnoses, monitoring and applications on the management and researching of current resources in various places of our country. in this paper, we attempt to analyze the changes in the use of the soil on the land of the former sugar refinery since its closure, by means of satellite imaging from 1987 and 2001, and of geographic information systems (GIS). A multi-spectral and multi-temporal analysis of the images will allow to distinguish the kinds of soil coverage based on their spectral response.Departamento de Geografí

Solid-supported monolayers and bilayers of amphiphilic ß-Cyclodextrin

This paper describes the adsorption and spreading of B-cyclodextrin (CD) vesicles on hydrophobic and hydrophilic substrates, which involves a transition from bilayer vesicles to planar molecular monolayers or bilayers. On substrates that are patterned with self-assembled monolayers by microcontact printing (..CP), the CD vesicles preferentially adsorb on hydrophobic areas instead of hydrophilic (nonionic) areas, and on cationic areas instead of hydrophilic (nonionic) areas. Supported monolayers of amphiphilic cyclodextrins CD1 and CD2 were obtained by adsorption of CD vesicles to hydrophobic substrates, and supported bilayers of amphiphilic cyclodextrins CD1 and CD2 were prepared by adsorption of CD vesicles on cationic substrates. Contact angle goniometry, atomic force microscopy and confocal fluorescence microscopy (CFM) were used to analyze the supported CD layers. The fluidity of the supported CD layers was verified using fluorescence recovery after photobleaching experiments. The supported layers function as a supramolecular platform that can bind suitable guest molecules through inclusion in the CD host cavities. Additionally, the CD host layers were patterned with fluorescent guest molecules by supramolecular ..CP on the supported CD layers. The host-guest interactions were investigated with CFM and fluorescence resonance energy transfer experiments

Sequence-selective detection of double-stranded DNA sequences using pyrrole-imidazole polyamide microarrays

We describe a microarray format that can detect double-stranded DNA sequences with a high degree of sequence selectivity. Cyclooctyne-derivatized pyrrole-imidazole polyamides were immobilized on azide-modified glass substrates using microcontact printing and a strain-promoted azide-alkyne cycloaddition (SPAAC) reaction. These polyamide-immobilized substrates selectively detected a seven-base-pair binding site incorporated within a double-stranded oligodeoxyribonucleotide sequence even in the presence of an excess of a sequence with a single-base-pair mismatc

Monolayer-directed Assembly and Magnetic Properties of FePt Nanoparticles on Patterned Aluminum Oxide

FePt nanoparticles (NPs) were assembled on aluminum oxide substrates, and their ferromagnetic properties were studied before and after thermal annealing. For the first time, phosph(on)ates were used as an adsorbate to form self-assembled monolayers (SAMs) on alumina to direct the assembly of NPs onto the surface. The Al2O3 substrates were functionalized with aminobutylphosphonic acid (ABP) or phosphonoundecanoic acid (PNDA) SAMs or with poly(ethyleneimine) (PEI) as a reference. FePt NPs assembled on all of these monolayers, but much less on unmodified Al2O3, which shows that ligand exchange at the NPs is the most likely mechanism of attachment. Proper modification of the Al2O3 surface and controlling the immersion time of the modified Al2O3 substrates into the FePt NP solution resulted in FePt NPs assembly with controlled NP density. Alumina substrates were patterned by microcontact printing using aminobutylphosphonic acid as the ink, allowing local NP assembly. Thermal annealing under reducing conditions (96%N2/4%H2) led to a phase change of the FePt NPs from the disordered FCC phase to the ordered FCT phase. This resulted in ferromagnetic behavior at room temperature. Such a process can potentially be applied in the fabrication of spintronic devices